How does the Lensbaby Scout perform as a cheap fisheye lens?

Question: I'm interested in the Lensbaby Scout since it seems like a cheap fish-eye option, but I am unsure how it performs. What about the lens's quality (build quality, image quality, and optical quality)?. Are there any problems with its plastic body?
Answer: I've had limited use of a Composer and Muse. The build quality was acceptable, and I know they've held up well for the owners who use them regularly, though it's a pretty clear step below kit lenses in terms of fit and finish.
I think the amount of enjoyment you get out of a Lensbaby is most directly correlated to the optic you choose and your expectation of it. I've used the Plastic and Single optics and they just don't suit me -- I want tack sharp results and those simply don't do it for me; I find it frustrating trying to tell if something is in focus or wondering if this is just as good as it gets. I don't know how the fisheye optic compares but I would consider the quality of it and what your expectations are.
A different direction: if you want a fisheye for cheap you might also look at the Samyang/Rokinon/Bower 8mm fisheye.
Answer: Here's a detailed review from DPreview on one of the Lensbaby lenses (the Composer Pro). They cover the build quality shortly on the second page.
Answer: If you are looking for a low cost fisheye, a lensbaby is not the right tool for you. The strong point of the lensbaby is that it can change the focal plane in somewhat the same way as a tilt/shift lens does. That makes it great for artistic shots where you want random focus effects, but not good for extreme wide-angle, as you would expect from a fisheye.
If you are interested in the lensbaby for its intended purpose, the manufacturer is very customer-friendly, and you can look on the lensbaby web site or call them at 1-877-536-7222 (US phone number).
I think if you look at the images in their gallery, you will see that the hallmark of the lensbaby is a sharp focus falloff. Here's an example, so you see what I mean:

As you see, there is a huge wide-angle effect, but more dramatic than that is that the center of focus is so narrowly constrained as to give a somewhat bizarre effect almost like motion to the image.
Comment: Steve, Lensbaby actually offers a [fisheye optic](http://lensbaby.com/optics-fisheye), which is a relatively straightforward 12mm fisheye lens, without any tilt, shift, or bend.
Comment: Additionally, the "Scout" body specifically does not offer the tilting effect that the other bodies do, making it more appropriate for the authors intended use.
Comment: Yes, that's true -- my bad. Scout is the only one I've not had a chance to use. I have the Canon fisheye, which was (past tense) very cost effective. The OP didn't say what brand camera they had, but perhaps the lensbaby will work out.


What is the definition of $\infty$

Question: I saw in a note that say $\infty$ is not a real number, and there is no interval of the form $(a, \infty]$?
So what is the definintion of $\infty$?
Comment: There is no standalone definition of $\infty$. But there *are* definitions of various expressions that involve the symbol $\infty$. In particular, there is a definition of $(a,\infty)$.  Note that there is nothing peculiar about this. There is no standalone definition of $a$ either, or of $($.
Comment: @AndréNicolas Yeah, you're right, I would mention that $a$ maybe a real number.
Answer: The symbol "$\infty$" is part of the ordinary mathematical alphabet. Like many other symbols in the mathematical alphabet, it has various uses. There is no standalone definition of $\infty$.  There are, however, precise definitions of various expressions that use the letter $\infty$.
In particular, in analysis, there is a definition of what is meant by the interval $(a,\infty)$. Note that there is nothing peculiar about the fact that there is no standalone definition of $\infty$, while some expressions that use $\infty$ have a clear conventional meaning. There is no standalone definition of $a$ either, or of $($.
Comment: Perhaps the following analogy will be useful. Suppose that we have written a program that finds, for any $n$, the $n$-th decimal digit of $\pi$. Then the command "Print $[17, 42]$" might mean print all the digits from the $17$-th to the $42$-th, inclusive. The command "Print $[17, 42)$" could be used to mean print from the $17$-th (inclusive) to the $42$-th (exclusive).  And if we wanted to print all the digits from the $17$-th on, we might issue the command "Print $[17,\infty)$".  But the command "Print $[17,\infty]$ would make no sense, no reasonable meaning can be assigned to the phrase "the $\infty$-th digit of $\pi$."
Comment: Since we're suggesting edits, how about a quick comment about how $(a, \infty)$ can be defined in the real analysis context?
Comment: You might want to add the two lines giving the definition for $(a,\infty)$ in the real analysis context.
Comment: Sorry, I meant " ] " above!
Answer: You could also use $\infty$ as the point that compactifies $\mathbb{C}.$
Thus, it is convenient to use the point at infinity when constructing the Riemann sphere. So, in topology, it is used to  compactify certain topological spaces.
Comment: Including the real line ...
Answer: There are a variety of different concepts of infinity in mathematics.  When used in interval notation of this kind, something like $(5,\infty)$ means the set of all real numbers greater than $5$.  Similarly $[5,\infty)$ means the set of all real numbers greater than or equal to $5$.

What is the definition of $\infty$


Are there good tools for managing custom (homebrew) classes?

Question: The D&D 4e character builder works OK for the official classes, but doesn't seem to have much support for anything custom. Are there good tools for managing characters with custom (homebrew) classes?
Answer: There is a 3rd party app, cbloader, that can be used to extend and create new content for the offline version of the character builder (which you would need to find a copy of).
You should be able to implement a custom class in that, though you will need to know how to edit XML files.
Comment: @JoshuaAslanSmith Yes. To be specific you need to know how to edit XML files - I've edited my answer to note that.
Comment: Should note that understanding/experience with coding like javascript is basically a requirement to successfully use a custom class in cbloader.
Answer: RP Tools' Character Tool allows for a way to update the databases that contain character classes, and then build a character with that class. The problems with that are you have to do it manually as the editor is in development. Also, only a small portion of the existing D&D classes are entered into the tool. And lastly, it doesn't enforce any of the rules (only 1 feat/every other level etc.).
Answer: 4eTurnTracker lets you program customized powers for both characters and monsters. It extends full functionality to customized classes so long as you take the time to "program" everything in. It's also easy to mix and match stuff from other characters, since 4ETT lets you import and transfer anything in plain text as well as formatted text.
Mind you, 4ETT isn't designed for printing out character sheets, per se, so much as keep track of everything else during play. Still, since you can just click on your powers and then click on targets and have all the dice rolled and effects applied and tracked, having custom classes in there is the best of both worlds :)


I've had a bike in storage for over 10 years. What maintenance does it need?

Question: I've had a bike in indoor storage (my garage) for over 10 years. I'd like to get it back into good condition to use for my commute to/from work each day.
What things should I check/replace before I trust it to safely and reliably work on the road?
Answer: If the bike was in decent shape when put away, and has not been exposed to the weather, there's probably very little that needs to be done.
The tires would be the biggie -- likely they're checked and may need replacement (though not for certain).  Inflate them to listed pressure and check the sidewalls for cracks or bulges.
Assuming rim brakes, the brake pads may very well be hard and in need of replacing.  But you can't tell for sure until you try.
Otherwise, wipe off the dust, inspect for rust, and put a bit of oil on the chain.  Check that the wheels spin freely, with no play in the bearings, and that the steering tube likewise moves freely with no play.
Give it a test ride.  Make sure the brakes work OK and that the wheels don't rub as they turn.  Try a few corners to make sure there are no odd handling issues.
The shifters likely will be balky at first -- run them through their paces a few times.
Basically, if the tires are sound and the steering is good and the brakes are good and there's no massive rust anywhere, there are likely no major safety issues.  Dependability then becomes your concern, since you will be commuting, and there it's mainly the condition of the tires and how well the shifters work.
[I did miss mentioning cable housings.  The cables should be given a shot of spray lube down the housing tubes.  This is often all that's needed to turn a balky bike into a smoothly shifting/braking one.]
Answer: Your local bike store (LBS) can be an expensive solution in search of problems, if you follow my meaning.
Let me clarify: a few years ago I bought a mid-1980's vintage mountain bike which I intended to use for basically the same purpose the OP described. It cost me $20 at a garage sale. It had been a few years since I had been on a bike, so though I once knew how to change a tire, etc., I had long since forgotten. I don't know why, but it never really occurred to me to look on YouTube, ask on Bikeforums, and so forth. Long story short, my LBS charged me nearly $250 for a bunch of easy stuff I could have/should have done for myself: new tires, new tubes, new brake shoes, a little lubrication. In hindsight, it was my fault; basically I approached this like an idiot with an open wallet. It would have been worse, but I stopped them from doing a bunch of other stuff which was unnecessary and even more expensive (changing cables, new freewheel, blah blah blah). I still have that bike, and nearly 1500 miles later, I have a clearer understanding of what it needs and does not need. It didn't need all the expensive stuff they told me it needed.
If you're going to commute on this bike, you will need to remember/relearn a few things: changing tubes/tires, lubrication, cleaning, etc.
So while I agree the folks at the LBS can be a great resource, it's not always true. Before you go throwing money at this, do your homework a little. Post some pictures of the bike, either here or at Bikeforums, and include some closeups of drivetrain components: front and rear derailleurs, brakes, chain, rear cassette/freewheel, tires, and so forth. Include some specifications: are you the original owner? How many miles on the bike? etc.
Where are you located? Are there any bike co-ops around you? Here in SoCal, there are many. They are not hard to find. I took my vintage mountain bike to one and for $20 got some really good help.
Yes, some bikes probably require the extensive (and expensive) servicing mentioned by other responders. But I have a few bikes I've gotten used and I've put some miles on them, and in every case but one, the only things I did were new tires, new tubes, a little lubrication, new seat, new brake pads/shoes, and some cleaning. For the record, my vintage mountain bike (1986) is still running on the original grease in the hubs and bottom bracket, but it was evidently not ridden much by the prior owner(s).
Comment: Bikes are pretty much where computers are in terms of repairs. It's often prohibitively expensive to fix them unless you are doing it yourself.  No matter what the item (cars, computers, bikes, etc.) you are going to get charged $50-$100 an hour for labour.  This means that unless your bike is worth quite a bit of money, it's not worth paying someone else to fix it.  If you have no interest in fixing it yourself, it's often chaeaper to just sell, donate, or trash the old one, and buy a new or used but rideable bike than to try to repair an old by that needs a bunch of parts and work.
Comment: I pay for what I can't do myself, more or less. I do take my bike to the mechanic for certain things: broken spoke, things I can't figure out (bottom bracket creak), and so forth. The same is true with my cars, and anything else.
Answer: You should probably take it to your local bike shop. An experienced eye will be more helpful that advice from the internet
By descending importance, my suggestions are

Examine the frame for cracks (very bad, but unlikely to be a problem)
Check that the tires aren't cracking or rotted. Inflate them to the
pressure recommended on the side of the tire.
Make sure the brakes work! If they squeal, it's time to adjust them or possibly replace the pads.
Make sure the seat is at a comfortable height.
Inspect the chain for tension (it shouldn't sag) and lubricate it with chain lube
Check that the wheels are true (the LBS can true them for you)
Comment: I totally agree with this proposed priority, but for 10 years, most likely any lubricant may have dried out or degraded. Most rubber parts may also have degraded, and some parts may have corroded, so I add: Have the hubs, bottom bracket and headset disassembled, cleaned and repacked (at your LBS preferably). Change brake cables and casing, change brake pads and inner tubes. Your bike will feel like new.
Comment: @Jahaziel, +1 on brake cable housing.  You'll likely notice early on if the brakes don't close, but corrosion or build up on the cable or a kink in the housing can also prevent the cables from sliding back when you release your brakes.  Worst case, first time you really need the brakes, they don't release and you endo.
Answer: I think if you have to ask what your bike needs to become roadworthy, it is probably a good idea to take it to a shop of some kind. Doing things like re-lubing (or re-packing) all bearings, cables, replacing brake pads, adjusting stuff, etc... all adds up to a lot of work. If you haven't done it before it will take a long time, require tools, and you'll end up with less than optimal results.
What may not be obvious is that there are different kinds of bike shops. The ones that cater to enthusiasts (for lack of a better word) will tend to be more expensive and will push for pricey components and service charges. If you have a bike that is "worth it", you probably already know how to service it yourself or don't mind paying what it costs for a mechanic to fuss over it.
There are other bike shops, especially in big cities, that focus on commuters and used bikes. They have lower prices for everything and understand the point of view of somebody that wants to "bring back" a garage bike from a decade of idleness vs someone that wants to race in a weekly criterium.
As for what it "should" cost...
something like US$ 50-80 for tune-up labor + 50-100 for tires and inner tubes (depending on quality) + replacement for things that are worn or rusted.
A good resource for parts for an old bike is loosescrews. If you want to do-it-yourself that is a good source, or you can just use it to make sure that you're not paying $100+ for a $10 dollar part.
Comment: Just a philosophical comment - taking the bike to the LBS every time when there is a problem is a sure way to never learn to maintain the bike.
Comment: A bike that has not been exposed to the weather and was not already a high-miler when stored should not need to have bearings repacked.
Comment: Yes, probably not, but there was no indication of the initial condition of the bike and its actual current condition. Also unless we're talking about arid climates, a garage can be fairly harsh environment!
Comment: So long as the bike is not getting wet (beyond occasional condensation) the grease in the bearings will be intact.
Comment: http://loosescrews.com/  appears to now be a gun parts supplier


Why is 20 the starting life total for Magic the Gathering? How would the game be different if this number was changed?

Question: To my knowledge, each player starts with 20 life in nearly every MTG game ever played. But why exactly was the number 20 chosen? How would the game be different if we started with more or less life? If my friends and I started playing with a higher or lower starting life total, how would that affect our deck construction decisions? Which colors, types of cards, or general strategies would become more or less powerful?
Comment: @Dave The question "How would changing X affect the game?" isn't just a question about house rules, its an inquiry into the nature of the game itself. I personally will never change the starting life total in my games, but knowing how the extremes would affect the game lets me investigate the nature of how the balance works and how I can use it to my advantage. Inquiring deeply into the rules and the consequences of changing them is an in-depth strategy analysis more than it is a question about house-rules. :D
Comment: The part about the origin of 20 is interesting, but the rest of your question sounds to me like a "house rules that I haven't tested" question.
Answer: I like shuuja and thesunneversets' answers very much.
There's a theory of Magic that says every matchup is two roles: "beatdown" and "control". The thinking is that, regardless of your actual deck types, one deck's going to have a stronger endgame (putting it in the "control" role), so the other deck has to hurry up and win the game before it's too late (putting it in the "beatdown" role). Raising the life total would naturally make it harder for any deck in the "beatdown" role that wins on damage, however obliquely.
Any deck can conceivably end up in the beatdown role, so don't think that this lets slow decks off the hook entirely. The most obvious disadvantage is to fast aggro decks, because they're more or less playing the beatdown role in every match, and their win condition is, almost universally, dealing 20 damage to the opponent (a few are poison-based instead). Modern-day sets are often balanced under the assumption that a Red-Deck-Wins-style deck should be reasonably competitive but not dominating; this means that the deck's creatures should be able to reliably kill a "goldfish" in around 4 turns (at which point an opponent can drop Day of Judgment to reset the field).
The ability of archetypes like Zoo, Red Deck Wins, and Tempered Steel to deliver fast beatdown sets the pace for the whole environment: other decks play low-cost disruption because not doing so means you get blown out by aggro before you actually get to do your thing. Remove that pressure and you create room for much slower decks. Commander is a great example. With 40 life, you can safely focus on playing high-cost powerful cards and devote your first few turns to hand-sculpting and mana ramp. Mid-priced cards -- strong three-drops and four-drops -- are still very important, but you're likely to see many decks that don't play anything but ramp cards and cheap removal in their low slots. It's possible to build a successful aggro-style Commander deck, but you have to either heavily disrupt the other players' early build-up (so that your dudes have enough time to finish them off while their decks are still in stage 1) or play combo-style elements (e.g. Heartless Hidetsugu) to seal the deal.
In regular 20-life Magic, Skittles is a control finisher. In 40-life EDH, he's an aggro general. That's how much life totals matter!
Similarly, imagine a 10-life game. You go first, play a Goblin Guide, swing for 2. Before I even play my first land I've lost 20% of my life total and I'm facing a four-turn clock. Do you have two Lightning Bolts in your hand? Goblin Grenade and Gut Shot? Fling and Mutagenic Growth? Practically any two or three fast cards will be enough to make me scoop my one land and go home. I have to have some very strong plays on turn 1 (or on your turn 2) in order to even see my own turn 2. What must my deck look like, then, if I'm playing combo and control?
So, in effect, futzing with starting life not only affects the pacing of the game and the relative strength of different decks but also completely changes the window of what's viable in a competitive deck.
Comment: +1 for a really good essay on the Beatdown vs Control paradigm.  Shifting players' starting life totals completely alters the sort of decks (and cards) that can possibly be competitive.  Do so at your peril!
Comment: Agreed! That's the cleanest description of Beatdown vs. Control I've read. +1
Answer: Point of order: all sorts of officially endorsed Magic games begin with different starting life totals than 20.  Excerpting from the Comprehensive Rules:

118.1. Each player begins the game with a life total of 20.
118.1a In a Two-Headed Giant game, each team begins the game with a shared life total of 30 instead; see rule 810, "Two-Headed Giant
  Variant."
118.1b In a Vanguard game, each player begins the game with a starting life total of 20, as modified by his or her vanguard card's life
  modifier. See rule 902, "Vanguard."
118.1c In a Commander game, each player begins the game with a starting life total of 40 instead; see rule 903, "Commander."
118.1d In an Archenemy game, the archenemy begins the game with a starting life total of 40 instead; see rule 904, "Archenemy."

Each of these variants accommodates different number of players, supports different sorts of politics and allegiances, and generally lasts a differing length of time.
I'm unwilling to engage in random speculation about what would happen if you tinker with the life totals in a standard 2-player duel: generally speaking this is a bad idea, because the power level of the cards is balanced quite nicely for 20 point life totals.  Lava Axe is a card that is well costed for the fact that it takes away one-quarter of a player's starting life total.  If players started with 100 life each, then Lava Axe becomes a considerably more awful card.
Conveniently enough, 20-point life totals usually allow for "best of 3 matches" to be comfortably played inside of an hour in tournament conditions.  If you have no time constraints and just want to play Magic all day, there is no reason why you shouldn't bump up the life totals as a house rule.  Just be aware that it will completely change the game balance, rendering some cards much better and some cards much, much worse.  Working out which is which could be a fun intellectual exercise for the jaded Magic player, but personally I like the fact that a lot of very smart people at Wizards have spent 20 years perfecting the game balance for 20-life-point games... why mess with that?
Comment: Wow, you're right. It IS possible for Lava Axe to be a worse card. :)
Answer: Not an expert here, but I the obvious change is that it makes it takes more damage to kill a player by damage, making decks that rely on that win condition slower. Then the question is, what sort of decks benefit from this? Clearly not aggro or direct damage, but combo decks would have more time to get their combo out vs one of the more damage-y decks, and control decks would have more time to lock down the board and implement their own win condition.
I think, within the categories of combo and control decks, those deck that win by means other than reducing life total (such as milling decks) will have their speed unaffected, whereas decks that rely on dealing 20 damage will now have to deal 40 damage, so they will be slowed.
As @thesunneversets points out, many individual cards will shift in value, e.g. cards that damage you or have you pay life will have a smaller relative effect on you and thus get better. However cards that deal direct damage to an opponent get relatively worse.
I would oppose your own comment and some of the comments in the other answer: do try it out in a two-player duel! Also try starting with less than 20 life. Find out how to adjust your strategy to these situations. Obviously you shouldn't play a standard game (or build a standard deck) in the same way as you would when starting with 40 or 10 life, but learning those differences will help you understand the game.
Comment: Most mill decks I'm aware of don't really "race". They either use milling as part of an infinite combo (e.g. Mindcrank / Bloodchief Ascension or Grindstone / Painter's Servant) or grind you down slowly after locking down the board (like the original Millstone deck, if I remember correctly).
Comment: True! I guess it's more accurate to say I don't think the milling itself is usually a race, but they "race" in the other ways that prison decks and combo decks do.
Comment: Your comment made me think a little more about what I mean. I do think mill decks race, whether it's a race to get the infinite combo out or lock down the board before dying (or your opponents' combo).
Answer: 20 is a convenient number, as it's the largest number on a 20-sided die, and the largest number comfortably placed around a small spinner; spindown dice have been available since the early days, and I've read that they were part of the original idea. Further, 20 is also the low end of the number of stones in a tube of gaming stones (the high end is about 40), and under half the number of mini-poker-chips in a tube of mini-poker-chips (which is typically 50).
Having played games with 10 LP, it doesn't cut the typical 45-60 minute time in half; it cuts it by about 10-20 minutes, as it takes a bit of time to get damage causing cards into play.
I've not played 30 point, but friends have, and it doesn't really lengthen the game that much, either; they say it adds another 15 minutes or so to the typical 45-60 minute game.


Where can I get a visa for Brazil in Texas?

Question: So I'm going to Brazil in March and I have no idea where one gets a visa. Do you have to go to a consulate, or a courthouse like where you get a passport? I'm in the Dallas area, so any help would be awesome!
Answer: Usually, depending on the country, an embassy or consulate is where you'd go to, in order to obtain a visa.
In your case, the nearest (that I can find) is the Brazilian Consulate in Houston, Texas.

1233 West Loop South,
Park Tower North, Suite 1150
Houston, TX  77027
(713) 961-3063/64/65 Fax: (713) 961-3070
E-mail:
email@example.com

So they'd be your most likely best bet for first point of call.
For a rough idea of the documentation you'll need to apply for your visa, have a look at the Consulate General of Brazil in Miami's website - they have a solid wall of information which will be of great use.
If you're really worried about the process, your travel agent would be able to help out with the whole thing. If you don't have a travel agent, don't worry, really, many of us apply for visas all the time, and while the wall of documents required sounds scary, as long as you follow the steps it's actually pretty straightforward.  Note that according to the Miami website, it can take 10-45 days to process depending on the method taken, so given you are travelling in March, I'd get the ball moving on the whole process pretty soon.
Comment: Yes, most of the consulates in Texas are in Houston (which is the largest metro area)!  Even though Austin is the state capitol, and is a pretty big and major city in itself, too.
Answer: If you don't feel like taking a road trip, there are a number of companies that can request the visa on your behalf (for a fee).
I initially found a company called China Visa Service Center that does this when preparing for my trip to China (although from the name, you can probably guess that they only do Chinese visas).
I have also used VisaHQ (for my Paraguay visa) and I was particularly impressed with their level of service (esp. because you can track your request online).
As an example, VisaHQ also can help with Brazilian visas (link applies to US citizens).
Comment: Ah, interesting. I have no problem doing paperwork myself, but I'll keep this in mind. Thanks!


USB DAW Fader controller

Question: Has anyone had experience with the Presonus Faderport or Frontier Design AlphaTrack?
Answer: I bought both the Alphatrack and Faderport a little while ago to A/B test them, decide which I wanted to keep (thank you Sweetwater!). Here's my conclusion:
ALPHATRACK: Really gorgeous device, buttons, etc, made editing a cinch. And it runs off of USB power. Which means you can mix in the airplane... I guess. But the fader is super loud - I mean loud enough that for automation following it completely invalidates itself as a tool for fine-tuning audio. I thought this may be a one-off, so I ordered a replacement. The two were equally loud. However, if you're mixing in an airplane, the sound of the fader itself probably isn't a problem :-P. I'm surprised more people don't complain about the loudness of the fader. Also, I hear that there's some latency in recording automation, but I did not experience this.
FADERPORT: It's bulky. It needs power (DC adaptor), and the buttons are a little sticky. And, I mean, let's face it, it ain't nearly as pretty as the Alphatrack. But you're not buying a single-fader control surface for the looks, you're buying it for the fader. And the fader on this thing is excellent. The device itself is cheaper, but my understanding is that PreSonus spent a lot more money on the fader itself than FrontierDesign did. Better fader = more power (hence, AC Adaptor) and less money for bells and whistles (hence, ugly interface, sticky buttons). But I use this almost every day. It's smooth, integrates perfectly in Reaper and Pro Tools, and quiet.
Comment: @ragamesound cool contribution! Thanks for the review.
Answer: I do have the Presonus Faderport running with Logic Express 8. The fader and buttons work, the panpot doesn't (when I twist it, the pan jumps from left to right irregulary).
The controller itself feels good, even if you have to press the buttons really hard, which is why I rarely use them.
To be honest: I used it for one project, but right now I do 90% of the automations via the editor in Logic or with the with the controller knobs of my MIDI keyboard. I won't sell the Faderport, but I won't buy it again, since I rarely use it.
Answer: We have the AlphaTrack in one of our studios and Command8 in two studios. I think it's a bit shaky, it makes some errors while recording fader moves in Protools, so I often end up mixing with the mouse instead of the fader.
When I'm using faders, I'm often using more than one fader, for example balancing music tracks to reverb returns. This is not possible with the alphatrack. I strongly recommend getting a Command 8 over a single fader controller.
Answer: I use the PreSonus Faderport for a year or so now and it made my life a lot easier. For the money you spend on the one little devil it works like a charm.
It is true that sometime the pan-pot knob does not respond well but if you cannot afford something large like a Mackie controller then it is very good (and cheap).
I haven't used the Alphatrack so i cannot give you some some feedback. But i use the Faderport on all my projects for the time being, the best part is the automations though, it supports all the Logic modes for automation and i found it very very useful till now.
Answer: I've used Faderport on Protools 7.3 & 8 without any probs. Good product, good value.
Answer: Presonus Fadeport with Nuendo and Ableton... buttons are slightly heavy to touch but ratio between price/value is excellent.
Answer: http://www.youtube.com/watch?v=NcfTYQW38fU
If you haven't seen that, it's pretty interesting.  The Faderport's automation is significantly smoother.
Comment: i think i read somewhere that the Alphatrack firmware has been updated since then, to react more quickly...
Comment: Could be.  At that pricepoint, I'm sure it's sixes either way.

USB DAW Fader controller


Can a HSM be used to make password hashing stronger?

Question: Say a database server has a HSM which is in use for encrypting (reversibly of course) credit card numbers. Is there any way a HSM could be used to add strength to a password hashing scheme? (Or are there any password hashing schemes that make use of a HSM to be more secure than pure software schemes)
Answer: You could, instead of hashes, use a MAC. That's a kind of hash function except that it uses a secret key, which is needed to recompute it. You would store the key in the HSM. The HSM would be needed to verify the password; if an attacker steals your database, he still cannot run a dictionary attack. This kind of scheme is sometimes called peppering and a HSM is the right way to use a pepper. To defeat such a system, the attacker would have to hijack the HSM and use it to "try passwords".
Comment: I'm surprised that using a HSM or at least a dedicated computer aren't more common among large website.
Answer: You could hash the passwords, store the hashes, and perform all hash verification inside the HSM, so that no hashes reside on the machine that provides the rest of the service.
This provides a separation of duties, which may be useful in high security scenarios. In order to extract hashes for cracking, the HSM would have to be compromised.
However, this is a rather unusual use for a traditional HSM, which is usually utilised for storage of sensitive data which must be reversible into its original plaintext. The idea is that one single secure built-for-purpose device stores the encrypted data and keys, and can provide unencrypted data upon request.


Distributed rendering in adobe premiere cs 6

Question: Does adobe premiere cs 6 supports distributed rendering? I have been searching and have found very few info about it. If it does, could you point me to a tutorial on how to set it up?
Answer: CS6 does not appear to offer distributed rendering as such. Premiere CS6 via the Media Encoder (which all Adobe video apps can use), can render your work in the background though, which may help:
http://tv.adobe.com/watch/cs6-creative-cloud-feature-tour-for-video/save-time-with-powerful-background-rendering-using-media-encoder/
Hopefully this helps, David


What's the difference between google apps and web apps on the Chrome web Store?

Question: Even though I think many may find this question stupid, nevertheless I wanted to understand it. Also, are Google apps the one made using the Google App engine while the Chrome Web Store apps made using the Google Web Kit (GWT)? Is there any difference between the these two types of apps as far as the end user is concerned ? If not then why does Google need to have them hosted on separate urls?
Answer: Google Apps:
A suite of applications that are created, run and hosted by Google, which can be used by organizations / educational institutions. These include Gmail, Docs, Calendar, Contacts, Chat and some other stuff. Also gives you a Google id of the form email@example.com. All apps are also hosted on your own domain.
Google App Engine: A platform that Google provides on which you can write your own application, in either Python or Java. You write the app and upload it to Google, and they run it on their servers. They also expose some APIs which you can use for things like data storage, chat, email, images, authentication, etc.
Chrome Web Store: A marketplace that collects applications written in HTML / Javascript, and hosted on any server. Some of these apps may use APIs specific to Chrome to provide extra functionality while running in Chrome.
GWT: A framework that compiles Java code into Javascript code. It only deals with client side code and is server agnostic.
You can use Google Apps to provide mail, docs, chat services to your business. You can write any custom applications you want and host it on App Engine, or somewhere else. You could add the application you wrote to the Chrome Web Store if you want to. Finally, you could write the client side code for your app in Java if you want to, and compile it using GWT.
Does that help?
Answer: I wouldn't say that

[all] these apps [listed on chrome web store] are for Google Chrome browser.

Indeed, it's true for Chrome extensions only. But many applications listed on Chrome webstore also work fine with other browsers like Microsoft IE. The applications end up listed when you click the "Applications" button on Chrome (or type in 'chrome://apps' in the URL input). But this is merely a shortcut.
However many Chrome WebStore applications go along with Chrome extensions, though it's not mandatory. Also Google provides development kits and APIs but you can use other developement tools.
See What's in the store according to Google
Comment: The link returns Error 404. File not found.
Answer: First of all no question is silly.
Second what Sudhir said is exactly right, I will try to give you simplified version of that.
Google Apps is suit of application like Microsoft office but on internet.
Google App engine is a platform for developers to write application against it.
Chrome web store is like apps on iPhone but unlike phone these apps are for Google Chrome browser.
All these apps are pretty  much written in Java so end use should not have any issue with this.
Comment: the language the apps that run in chrome are written is is irrelevant; they're not running locally, they're WEB apps.


What can I use workspaces for, and how can they be used?

Question: I want to know why to use workspaces. I have seen many people using it but I don't know why to use it. Can anyone tell me why?
Answer: Workspaces help by uncluttering your main desktop and allowing you to run programs on each workspace instead...  Imagine web browsing on your main workspace while workspace 2 has your music player and workspace 3 has an important spreadsheet on screen ready for you...
Answer: I use it when I want to see two windows together at time, then I put this two windows in one desktop and when I click one, I see both. For example, Skype, I need to see the chat window and the video window at the same time, so I don't click one and the another one after, just I go to that desktop.
Answer: I'm sure everybody has their own ways of using workspaces. As for me, if I'm making a presentation or typing a document, I like to open documents/pictures in one workspace, play music through Banshee in another workspace, and have Chrome ready in a third workspace in case I need to look up some information. I felt that workspaces were useless/overkill for a long time, but once I started using them, I realised they're actually quite handy.
Answer: I've been using workspaces since the mid 90s and I can tell you that if you are using them to simply separate different apps you are doing it wrong. You already have dock icons to switch between apps.
Workspaces are a killer features when you organise them by projects or tasks. Usually I keep the first workspace for Skype, e-mail and general web browsing. The other workspaces are used for one task or project each. I usually have a web browser window in each workspace containing all the browser tabs related to the task.  Along with this browser window there are the other apps such as development environment, text editors, nautilus folders and terminals related to the task.
If I'm doing some image editing for example, I open in a workspace, the image editing programs, nautilus folders and a web browser window containing tabs with research related to the artwork I'm making. If I need to switch to programming, I just change workspace and I get all my programming related apps and browser tabs. I can then come back to my image editing stuff by changing workspace again.
Sometimes I put a project aside for a few days and I keep all the related programs and browser tabs opened. If someone calls me to ask a question about the project I set aside, I can switch to its workspace, lookup some stuff for them, and go back to what I was doing before in a few seconds.
Answer: I use them for switching from one application to another with shortcuts. Instead of scrolling through open apps with Alt+tab, I can just switch to the workspace where the desired app is supposed to be. For example, when I am working with the browser and want to write an e-mail, I know (or rather: my fingertips know, because it is hardly a cognitive process anymore) that my e-mail app is in the workspace on the left of the browser's so I just switch there.
However, that would not seem advantageous to me if I used the default shortcut for switching workspaces (Ctrl+Alt+arrow) since I would have to use both hands for that. That is why I changed it to Ctrl+arrow. My right hand got so used to it that it moves me around the workspaces very fast.
Answer: It is a great tool for multitasking
Comment: Can you expand this to explain how it helps for multitasking?


How to group ico files

Question: A while ago I noticed some .ico files actually came in "packs" that contained the same image in different sizes. I now need to create one of those packs (I have 10 different sizes). Do I need a specific software? Can it maybe be done online?
Answer: You can use a software that does it for you, or do it programatically in f.ex. Visual Studio.
Here is some software that can help you out:
Greenfish Icon editor (free)
IcoFX Pro (payed)
You probably know the reason why it comes in different sizes, but to make the answer more complete: the reason is that the system will choose the best-fit size for its current usage, ie. being displayed as an icon in a window title bar versus on the desktop etc.
Knowing this and for what purpose the icon will be used can assist you in only choosing the sizes needed and hence make the ico file less in size.
Answer: The GIMP's ICO export code can save multi-resolution icons.  Here's a very nice tutorial for creating such ICO files in the GIMP.
Basically, what you do is create a bunch of different-sized layers containing the same image (or different images, if you like) at different resolutions, and then save the image with an <code>.ico</code> suffix (or any suffix with "Microsoft Windows Icon (ICO)" selected as the file type), which will present you with a dialog containing additional options on how to save each layer into the final icon.

How to group ico files


Tools for designing CSS layouts

Question: Could you please advise me the tools that can draw images like
this or this serving as a design for CSS layout?
Answer: I generally do wireframes in photoshop, but you might like to take a look at http://balsamiq.com/ which is a mockup / wireframing tool with a "sketch" style.  It's more focussed at UI mockups than specifically CSS I think.
Answer: Maybe I read the question wrong, but I thought perhaps it was seeking a tool to output a line-drawing representation of existing CSS and markup. If so, the Fire Fox Web Developer toolbar can help.
Under the Outline option you can have it outline different sections of your page to see clearly how all the elements of your page are nested together. I have found this extremely helpful when trying to troubleshoot a complex layout that someone else has written.
Answer: It's not too clear what you are asking for, if you need a tool that generates CSS and layout for you then you probably could use 960 Grid System, if you need a tool for creating mockups then you could use Pencil or the tool Matt has recommended you.

Tools for designing CSS layouts


Linux compability file system

Question: I need to develop a file system for Linux for my diploma work.

Where can I find infomation about this theme?
How can I test it and other?
Answer: You want to start with FUSE -- all it requires is your implementation of system calls like open and unlink.
A tutorial, written using the Python bindings, is available at the FUSE Wiki.
Answer: Which way to go really depends on if you want to do kernel programming or not.  If not Then your only reasonable choice is FUSE.
If you are more novice, and never worked in kernel, FUSE might be worth looking at.  If you have solid programming experience, especially kernel, writing a real driver will yield better performance and stability.  Of course, this assumes programmer time and experience are not in the equation.  You could always write a kernel FS driver, of such horrific quality, that a comparable FUSE implementation could be better.
If you want to do real kernel programming, specifically on FS, you might want to consider Linux NTFS.  The kernel really needs a full write/read high performance/stability NTFS driver.  ... Two birds with one stone, major contribution and thesis in one.
Comment: Don't lure an obvious newbie into that dragon-infested place (NTFS is undocumented, and a very complex beast; it took many experienced kernel hackers to reach the current state).
Answer: As for any such project: I'd suggest you hang out with the people doing filesystem work, and help out on some of the existing pieces of code: it is normal for a new filesystem to take some 5 years of solid development work by experienced hackers to get to the point where normal people will dare touch it with a 10-foot pole.
Answer: Actually this can take a long time, even if you have experience in developing low level, in addition to knowledge of the kernel. I recommend you to be part of any established project and offer some improvements. Even this may also result in a demanding job and recognized by the educational institution and the developer community.

Linux compability file system


Is there a way to copy text style in Photoshop?

Question: Is there a way to copy text style(font, weight, etc) in Photoshop?
Comment: just as a note, link all the needed text layers could help.
Comment: there is in photoshop CS6
Answer: Character Style and Paragraph Styles are designed for just this.

Much like layer styles, you simply format a text layer how you'd like it then click the little "new" icon at the bottom of one of the style panels. This will create a new style. When you then wish to format text to look like that style, simply highlight the text layer and click the style in the Character Style or Paragraph Style Panel.
Character styles will alter just the text - font, face, size, etc. Paragraph Styles will alter paragraph options - alignment, spacing, etc.
Answer: Yes, there is. Ctrl + click (with + shift or shift alone, if there are many) all text layers in layers dialog to select them, then in character settings window, just set italic, font-family, weight, etc. For layer style, has been explained above.
Comment: This method does not copy character styles, it 'applies' your selections to multiple layers. This is different from copy/paste.
Answer: Layer style? Or actually text style?
Right click on the layer to copy the layer style. Right click again to paste on the new layer.
For the text formatting itself, duplicating the text layer is the easiest option.
Answer: Duplicate the text layer? That's what I wind up doing.
Answer: If you select a text layer with the text tool it will copy the text style. But the text size isn't copied across if you use transform tool. If you use the font size selector it works as expected.
Answer: press and hold alt and drag the text need to be copied.
All layer styles will also copied.


How long does a typical car battery survive without recharging?

Question: I sometimes will stay in the car for extended periods with music player, parking lights turned on and engine turned off. I was wondering how long can the car battery survive this load. Should I be worried about this?
Answer: The question can only be answered if you determine the load that is being put on the batteryand the load capacity of the battery.I have run the radio in my truck for two hours and it started without a problem.I have seen a luxury car with 12 or 14 interior lights run a battery down in 90 minutes from a door left open.Most original equipment radios draw very little current so that isn't much of an issue.What can be of concern is if you repeatedly drain the battery with powerful stereos,lights,powerwindows etc.  then recharge it by running the engine. it will shorten the batterys' life along with the alternators'.That being said if the alternative is to idle the engine adding wear to the engine, batteries are cheaper than engine overhauls.If what you are doing is sitting for 10 or 15 minutes listening to the radio it really should not be a concern.
Answer: I have a heavy duty truck battery in my car, and I can run a 640 Watt stereo system all day and all night, with the interior lights on without having any problems starting the car.
But once I accidentally left the lights on for two weeks while on holiday, and the battery was flat.
Those two datum points give an idea of the expected life (the truck batter is about twice the rated capacity of the normal car ones - which is why I bought it)
Answer: I know every vehicle is a little different, but there's a drive in movie theater close by to where I live.  Most vehicles there have no problems leaving the stereo on for 2 hours and then starting the vehicle.


Which MPI package should I install?

Question: I want to attempt some simple programs using MPI on my desktop which runs KUbuntu 10.04.2.  Which MPI package should I install?
Answer: If it's just for simple usage on your own system, OpenMPI is very nice, as it doesn't require any setup after installation, just running your application with mpirun is sufficient.
sudo aptitude install libopenmpi-dev openmpi-bin

Answer: There's a great Guide in the Ubuntu Community Help on using the MPICH2 implementation of the MPI. It's a bit old (the Guide I mean), but it should still work as described.
The specific package you're interested in there is  mpich2.

Which MPI package should I install?


Resonance Realms - Why bother?

Question: Why as a player should I care about resonance realms? I understand that the actual character would be totally into hanging out in them, but from a gameplay point of view, why should I care?
Answer: Unfortunately this is mostly in relation to how your GM runs the game.  The resonance areas are like the astral realm: If you GM doesn't really support it, they mostly become flavor for the setting.  However, when used you have alternate routes to find info and wreak havoc... And so does the environment.  The primary downside is spotlight time.  When you go somewhere the other players can't (unless your GM lets them control your pets). That means the game is focused solely on you.  Especially considering that you usually get extra passes per round even when the GM straddles the two (or three) worlds.
If this question is geared towards how you would make your character, you should talk to the GM about the setting and how they will use your technomancy.
EDIT1: You may want to make a character less inclined to use the realm as a backup and explain to your GM that this is merely an alternate build in case they don't support the way your character is (expensively) built.
Comment: @Eforen The gameplay benefits depend on what the GM decides is possible, and how much of what's possible he makes available to you.
Comment: I already made the char I was looking at the gameplay benefits of using it.
Answer: As a gameplay benefit, I read somewhere in the Unwired book that "Resonance never forgets", and a Technomancer accessing its Realms could retrieve any deleted file (assuming they were in a Matrix-connected hard drive, I think). Your character could also meet there precious allies (and deadly foes).

Resonance Realms - Why bother?


What NPC gets attacked first when attacking an NPC party in an RPG?

Question: Let's say I am in a battle with four trolls, and I have the highest initiative, so I attack first. Should I randomly choose a troll to attack? Proximity to each troll does not matter (it is not a factor in the algorithm). I remember playing an older RPG (I think one of the Final Fantasy games on N64), and the attacks appeared random. You might have one troll that never gets hit, or you might have one that always gets hit. Is there an acceptable standard?
Comment: What's wrong with letting the user select which one to attack?
Comment: Nothing. That is an option as well :)
Comment: There were no Final Fantasy games on the N64... but for the most part, most of the early Nintendo ones (outside of the first) resolved to random choice. Enemies didn't really have a row or priority system like the party had, so random choice just went to any old target.
Comment: It might have been Super Nintendo (that was so long ago :)... all I remember is my friend being so pissed that it appeared so random after he made an attack. That might be an indicator that if a player can choose, then that would make it more fun.
Answer: If you don't have a good reason for otherwise, then the player always chooses.
Comment: Let the players choose, its a game not a cutscene :)
Comment: -1 That's a gameplay design matter, that doesn't answer the OP's question, just tells him not to make a decision he probably has already thought of and concluded that it's best for his specific game. Maybe he needs some sort of an "aggressive" mode where the player character automatically attacks enemies in sight?
Answer: The biggest troll or the most dangerous one.
Comment: ... which is true since RPG is the best game genre; all others are so unrealistic.
Answer: You could solve an equation to see which strategy is the best.
There are 4 trolls and they all are different. Each one does N damage per second and takes T time to kill. In said example you have 24 possible killing sequences (1-2-3-4, 1-2-4-3, 1-3-4-2, etc..) you can estimate/compute all of them in under 1ms and choose/suggest the best strategy for the player.
Of course it would be nice if player could choose any one he likes to be killed first instead :)
Answer: From a realistic-y type PoV:
The heroes aren't really going to know 'oh look, this troll is the most damaged' or 'this one is the largest threat' too much. Mostly since they'll be avoiding getting hit. They're going to attack whatever is closest to them. As such, I would say in  the situation like this (H for Hero, E for Enemy)

<code>  E1
</code>
H1   E2
H2   E3
       E4 H3
<code>  E5
</code>

H1 will go for E2, H2 for E3, H3 for E4.
The other option is totally random, or let the player choose. It's probably easiest to let the player choose to avoid 'whoops, accidentally didn't kill the boss who had 3hp left oh look I am dead'.
Answer: There are a bunch of different ways to solve this problem, as others have said. This ranges from a completely random choice to completely player chosen.
One game that has the style of semi-randomness that you were talking about was Ogre Battle 64. All attacks were done without player choice, but you could direct how you wanted your squad to act. The options were autonomous (pretty much completely random), target weakest (try to kill the enemy with the weakest health), target strongest (slowly weaken the opposing squad), or target leader (without a leader, the squad tries to run back to their base).
The kind of system you want depends on the kind of game you are making. The typical Final Fantasy game is not based around large scale strategy, but are more based on the individual tactics of a single fight; allowing for almost complete player choice tends to be the best bet for this style. In a squad based game, like Ogre Battle, you may want to make the player focus more on the strategy, such as where the squads are placed on the map, or which enemies to kill or weaken first.
Answer: Depends on how smart you want the decision to be, which is a gameplay design decision - do i want a fluid gameplay where your AI party members automatically pick the correct things to hit on the head so that the player can just do his thing and keep hacking and slashing without being interrupted, or do i want "dumb" party members so that the player has to use his head and make all strategical decisions (maybe even after pausing the game)?
In Dragon Age (might have been done before so don't kill me) for example they've let the player pre-script the behavior of his party members and tell them how to "automatically" make that decision (and others as well).
About the AI picking which one to start striking first - are they all identical and distance doesn't matter? In that case i don't see why not pick a random one. Otherwise some things to take into consideration are which one would be the fastest to kill (least armored, smallest health buffer, already damaged)? Which one deals the most damage? Which one has an ability to heal it's allies? Which one has misc abilities that might be a threat - such as temporary disabling your friendly characters and debuffing them. Based on those and other factors you should make some sort of a score system, you check which troll gets the highest score, and this one gets attacked first.


What are some character development tools?

Question: I have a character that I want to develop slowly through the campaign.  By this I mean I want him to slowly mature and change his personality through the sessions.  What tool or trick can I use to keep myself on track when roleplaying him?
Answer: This answer comes from a MMORPG-oriented roleplaying group, but it's a good one!
There's this technique called a character diamond. Basically, you choose four words that define the personality of your character: for example, my fighter Collin is modest, taciturn, gullible, and underwhelming. You're looking for things that don't overlap; the link provides a longer explanation, but that's the core of it.
That gives you the heart of the character. You can actually write them down for reference, which is maybe a bit goofy but I find it can help. Then, when you're thinking about more transient or temporary traits, you can think about how they relate to those central concepts. You also know that if you want to change one of them, it's a big deal and deserves a lot of preparation. Or maybe just a real life-changing event, but either way it'll remind you of the stuff that was meant to change slowly.
Comment: Nice. I always liked rolling the personality tables in the D&D 1e DMG with the proviso that you can change any roll you don't like. The list here is just right for d100; I just rolled MANIPULATIVE, SELFISH, METHODICAL, and ECOLOGICAL. Sounds like a right bastard :)
Answer: One thing you could do, possibly in tandem with Bryant's response above, is use your character's traits in a way similar to "Keys" in a game called The Shadow of Yesterday. In that game, every time your character does something directly related to a Key they gain experience. So, if you had a Key called "Greed", you might get experience whenever you hide loot from your companions, or put yourself in incredible danger in order to gain something of monetary value.
Instead, you could decide that after your character exhibits or acts upon a trait a certain number of times that you will transition his behavior in that regard towards something different. You can just put a series of check marks by the trait to keep track for yourself.
Answer: The Burning Wheel RPG uses techniques specifically for this kind of development, and it's reward cycle is based heavily on this.
At the core of the system lie Beliefs, Intent and Traits. Beliefs tell you what your character wants (more long-term), and traits are personification(s) of Beliefs. (I'm simplifying).
Check it out if you like.
Comment: You might say a few words about the trait vote, which seems relevant for the question.
Answer: Ask for feedback on your interpretation to other players. Ask them to keep and eye on those special details that make your character special, and try to think in advance how and where are you going with them.
I find usefull to mimic some expresions, habits or ways from films or books, adapt them to my character, and then develop them in some way or another with help from the group.
Answer: I generally start with a rather empty shell (but still with a proper backstory), and then let the campaign define his/her morale, objectives, hopes and dreams. Sometimes, there are critical events that form a character, and they are decided by a die throw. I save down these critical events in her character sheet, and let my fantasy fill the gaps on how the character behavior evolves.
For example, a character of mine, Female elf, cleric of Lurue, had to save his comrades who kept falling down a cliff. She was determined and helped people despite her poor skills in climbing and high danger to fall to her death (we are talking of a 1st level character against a CD 18 cliff).
Later on, we had to go into an academy and study sorcery. Due to very poor throws, she was unable to learn anything, and a critical 1 lead her to throw the book out of the window.
These events defined her as a very good person, but rather unable to focus, and not particularly skilled with studying. As a result, I left her reach the 17th level Cleric with just one grade in Knowledge (Religion).
She married and had a child from a paladin (another player's character), but then was abandoned by him. She kept her wedding dress "as a memento for regrets".
Later on, I reused the character as a young apprentice in a prequel campaign DM'ed by me. She kept the same characteristics: a very caring, generous and good person unable to deal with formal training, and respect for the rules. She is a character which all my friends and I remember with great affection.
Comment: While this answer does explain how details of a character might be invented over time, I'm not too clear on how it answer the original question, which was about ways of managing a character's changes in personality. Changes in personality require the presence of a defined personality different to the end product; your answer does not. -1.
Answer: There are quiet a few good examples of techniques and tricks in literature -- in fact, it could be argued that any good literature will contain just that ^_~.  Pick books, TV series, and plays to read.  Most of them will have character progressions.  Just as an example, I would suggest looking at Babylon 5, in particular G'Kar and Lando Molari as examples.  Both change drastically through out of the show in response to events that are happening.  Many of those events are choices those side effects full y escape them.
Define critical moments that changed your character's outlook.  Make sure you refer to those from time to time -- "Remember that time in X" --.  If elements of that are reflected elsewhere, you can assume a flash back:  Your life changed in a bar while drinking whisky.  Every time whisky is offered, make sure your character reacts strangely.


Greyed-Out vs Invisible

Question: What is a good criterion or rule-of-thumb for determining when a control should be greyed-out and when should it be completely invisible?
Comment: possible duplicate: [Don't hide or disable menu items?](http://ux.stackexchange.com/q/12756/7627)
Answer: Grey it out when you want the person to know that the control exists, but that it is disabled.
Hide it (make it completely invisible) when it doesn't matter whether they know that it is there or not.
In general I would opt to grey out controls rather than hide them, because someone could remember seeing a control somewhere that then not be able to find it again if it is now hidden.  And there would be no indication why they can't find it again.  When you grey out a control, you can have a little  icon or something similar to let a person see why it is disabled.
Microsoft ran into this problem a number of years ago in MS Office, were they would hide menu items that you hadn't used in a while.  It caused so many support issues, that they eventually dropped it.
Note that, however, there is one important exception to this rule: If the software assigns different roles to different groups of users, the ordinary users should not be aware of the advanced functionality available to more privileged users. For example, a forum moderator could be allowed to ban users, delete entire topics, etc. In such a case, the advanced buttons (menu entries) should be completely missing from the ordinary users' GUI (and not just grayed out).
Comment: Currently, such a procedure is often a tool to encourage users to upgrade the system (often also to extend privileges thanks to it), but it always goes hand in hand with labeling such an unavailable function (which may be available after purchasing a higher version of the product, etc.)
Answer: It depends an awful lot on how you expect the application to be used.
If all your users are power-users (like Photoshop in @edgarator's answer) then you typically want to grey out rather than hide - you want your users to know that the feature is there, and they're going to be using your app for a while.
However if your users are less technical or (more likely) only occasional then you don't want to clutter the interface with controls that they're never going to get round to using. They're not going to hang around to find out why a particular action or control is disabled.
In these cases I switch to a few rules:

If the action is never going to be available to the user (for instance if they don't have rights or they haven't purchased the feature) then always hide it. I hate blank buttons on the dashboard of a new car.
If the action can be enabled by user action on the same page/screen (for instance a next button that needs a mandatory input box filled in first) then mostly disable.
If the action can be enabled by the user by doing something on a different page/screen then it comes down to whether you want them to go find how to enable any greyed-out options. Usually I find that it means you'd be better off rethinking how the pages/screens flow through what the user is trying to do.
If there is a lot of disabled functionality, for instance a whole extra block of form inputs then it's a judgement call. I tend to hide it and then highlight it should the user need it.

Basically the goal is always that the user can use it with the minimum of manual, so grey out something when you want them to know that there's something they can do to enable it. Hide an action to avoid distracting them.
Answer: This reminds me of Woocommerce, where they hide the all-important add to card button unless all options have been chosen.
Take a look at this:

vs the subsequent screen which shows the add to cart button and the number of items you want to buy. What if you wanted to buy two shirts but different sizes?

Hiding the most important parts of your navigation or CTA buttons is not a good idea in this case. In most of the cases, you can make use of greying out as a subtle indicator of optional functionality:
Comment: That's a weird one. Also, I think they were trying to be cute, but does "Flavour" actually refer to the color?
Answer: This question is very general. Without context it's hard to give an answer that would help. So this answer will be very general as well.
There are generally two reasons why an element can be active or not:

The action the control would cause can't be invoked (e.g. a disabled "save" button because not all required data has been specified)
The application is in a mode that doesn't support the control (e.g. disabled font dropdown while an image is selected)

In most cases, disabled or hidden controls are a result of modes: Showing a disabled element suggests that this element can, somehow, be enabled – usually by changing the mode your application is in. Think switching characters in a game: different characters will allow different actions, thus the player is in the same application (the game), yet what they can or can't do is determined by the mode they are in (the character they currently control).
Modes are a very troublesome thing for users, since the same UI may or may not allow different actions depending on the mode. The big problem is how to let the user know in which mode they are, and to make obvious how they can change it. This is where most applications fall short: Users find themselves desparate because a control can't be clicked, and the only clue the application gives is e.g. a small icon in the status bar.
Be assured: Users will look for a way to enable disabled elements.
Invisible controls may lead to confusion and disorientation.
Disabled controls may lead to investigative behaviour (which can be a good thing).
One general piece of advice: Keep the amount of hidden/visible and inactive/active controls at a minimum. Usually, there's a better solution.
Answer: This is what apple says about hiding application features according to its location:

People should be able to find all the available features in your app.
  Don't hide features by failing to make commands available in a menu.
  Menus present lists of commands so that people can see their choices
  rather than try to remember command names. Avoid providing access to
  features only in toolbars or contextual menus. Because toolbars and
  contextual menus may be hidden, the commands they contain should
  always be available in menu bar menus as well.

Some disabled UI elements may hint users on application's behavior. When you hide them that hint is gone.
Take for example Photoshop, when you're in Indexed Mode (Like working with a GIF) you get this screen.

As you can see, the buttons in the bottom right are disabled. And that's typically what hints me that I need to go and change the image mode (between parenthesis next to Untitled-1 @ 100%).

Now they are enabled!
As you can see the mode change is usually subtle, but the application manages to communicate the mode in many ways. If you just hide the buttons, you would just thing that the toolbox was closed at that point or start wondering about whether the application is running properly.
Answer: You should only make something invisible if it has no relevance to what the user is currently doing and doesn't provide any value for the user.
Forms are a good example. There's no point in asking a user to fill out employment history form if they never been employed or asking them to fill out a credit card form if they are paying with a gift card.
Greyed out controls suggests that the item is not active or disabled, but the user should be aware that it exists.
Answer: In error scenarios also we can hide. Assume I need to show a checkbox on page load, if there is a failure to get the current toggle status, disabling that would confuse the user, as he didn't make any mistake or his actions didn't cause it, it is a failure in fetching the information. So I assume in this case also we can hide.

Greyed-Out vs Invisible


How much time is lost by waiting for GUI?

Question: After asking the question Will faster GUI always make one more efficient?, I understood that there is a lower limit to the amount of time lost due to the GUI not responding. My interpretation of the answer is that below 50-100 ms will have a neglectable effect. Now I am interested to know whether there are any studies on longer waiting times. I would be especially interested for in the ranges from 10 seconds up to 20 minutes, which were not covered by the study referred to by edeverett in his answer to the other question. I am interested in cases where the waiting time is happening on random so the users do not get used to it.
Comment: Can you give an example of where waiting time would be random?  I work a lot with EDA tools, and they can have waits from a few seconds to several hours, but the times are hardly random.
Comment: @James Crook.  Opening Outlook on an ovetloaded Exchange server can take anything from seconds to half an hour. It certainly feels random, at least.
Comment: Great example.  I'm on the same wavelength now.
Comment: A bit off-topic but I never understood why anyone would run Outlook without cached mode enabled. It starts instantly and doesn't block user input while trying to establish its connections...
Answer: Related questions have mentioned http://www.useit.com/papers/responsetime.html which says users have to reorient themselves to the task if the waiting time is over 10 seconds. As I understand it the theoretical basis for the 10-second figure is that short-term memory decays in the 2 to 10 second range (or the user's attention wanders and pushes other things into working memory, depending on the psychological theory you subscribe to.) Once the user is back on task they use long-term memory and the information presented by the UI to figure out where they were.
I don't know what theoretical basis there would be for a threshhold in the 10 second to 20 minute range. I have heard two minutes suggested as a guideline where a different type of feedback is called for (e.g. notification instead of progress bar) but I think that was motivated by the idea that users would rather multi-task than wait that long.
Answer: Once I did a conversion from Lotus 123 to MS Access of some workflow database forms. The user were typically spending 6 hours on registering all the data in one particular work flow when using Lotus 123. After I had converted to MS Access, he used half hour on the same job! This was basically just converting everything bit by bit without restructuring anything. It did all in the same way and GUI look in the new version. It was just the difference in response time in the two systems that caused the big difference.
Answer: Depending on what you do I'd say that wait times are not a big problem but reminding the user once an action is complete can be very important.
Triggering a visual alarm after the action finishes could let the user react pretty fast after an event and improve performance.


How do you make a story succeed in spite of an unsympathetic main character?

Question: I'm looking for techniques specific to a story with an unsympathetic main character. Confederacy of Dunces, for example. Why does that work, and why wouldn't that work with a likable hero?
Comment: I agree, I've confused "unsympathetic" and "unlikable" here. And that's worthy of an entirely different discussion.
Comment: It works because the sympathetic characters (of which there are several) do manage to prevail over their difficulties in the end, and the characters that are even worse than Ignatius get their comeuppance.
Answer: Some great answers, but I disagree in some regards: interesting and compelling and understanding are not enough for someone to carry on reading about a main character. I can find a serial killer interesting and understand his motives, but if he's killing children, it's extremely unlikely I want to keep reading about him unless the author has tricked me into sympathising with him.
In any good book, the reader must sympathise, identify and empathise with the main character, and must want to be completely sucked into their shoes. Without these elements, your main character likely won't appeal, except perhaps as a villain, which is different (but avoid the "absolute evil" approach, as this simply makes him a caricature).
I don't think it's impossible to get the reader to sympathise with all manner of "anti-heroes", no matter how reprehensible. If your main character is so reprehensible that there is no sympathy at all for him from the reader (or even you, as the writer), then you probably should reconsider how your character is portrayed.
The reason for this is because the reader needs to follow this character every step of the way, and will him to succeed in his endeavours. If we have no sympathy for him, we will not want him to succeed. If we don't identify with him, we cannot relate. If we don't empathise, we don't care enough about him to want him to succeed. Worse, we don't care enough to want to even know whether he will or won't.
As an example, consider The Godfather. Right in the beginning, we are introduced to a man in court watching the men who raped and beat his daughter get off with a slap on the wrist. Justice has not been done. So he goes to Don Corleone who is at his own daughter's wedding, and asks the Don for his help. Don Corleone agrees to carry out justice on behalf of the man. We see the respect that Corleone and his family command from people.
Right there, in that instant, you as a reader have taken the side of Don Corleone. You sympathise with him, you can identify and empathise with him. Here is a mobster, head of a powerful crime family, responsible for the murder of many people, yet you sympathise with him, because he's a man of justice, a man with a code of honour that allows the reader to will him to succeed. You want to be drawn into his world.
A common way of invoking sympathy is by putting the character in danger: their life could be in danger, they could be under threat of losing their job, their wife - all manner of devices that immediately invoke sympathy from the reader.
Alternatively, you can portray the character in a way that everyone can relate to: perhaps he's experienced some hardship like divorce, a death in the family, some "wrong" has been committed against him that immediately gets the reader on their side.
Another trick is to use the character's reprehensible traits in a morally justifiable way. For example, consider the example I gave earlier about a serial killer. What if the serial killer only kills serial killers? That's exactly what happens in Dexter, and we are interested because, even though he's a serial killer, he kills only bad people. Suddenly, his actions take on a different moral light, and we actually will him to succeed.
I'm sure there are other ways. Pick up Confederacy of Dunces, and rethink how the characters are portrayed to induce sympathy in the reader. I haven't read it, but I'm sure you'll find what trick the writer used to get you onto the character's side.
Comment: I agree.  Unsympathetic is not the same as disagreable, unlikeable, or flawed.   Sympathetic means that you can share their feelings and see their point of view.  I would say that your protaganist has to be sympathetic, even if they are not a nice person in other regards.
Comment: A good answer! (though it did make me think 'how could you write a readable character that *did* kill children! - or was utterly reprehensible in some other way) - I wonder if that's worth a question
Answer: I haven't read Confederacy of Dunces, but I think in general, it's not as important that your main character be sympathetic as that s/he be compelling.  I can read a book about reprehensible characters and love it as long as I'm intrigued by the main character: Hannibal Lecter (Silence of the Lambs, etc.) is super-intelligent and creepily charming; Patrick Bateman (American Pyscho) is, well psycho, but also clever and just intriguing; Macbeth could have been so much more, etc.  As long as they hold my INTEREST, they don't have to hold my affection.
Like any character, you need to be sure than an unsympathetic character isn't flat, and isn't a cliche.  Can you introduce an element of humour, so that the character is wryly aware of his/her own shortcomings?  Or can you show the character growing and changing through the story?  It doesn't have to be a complete about-face, but just a little improvement can go a long way.   Or could you give us enough background on the character so that we understand the nastiness, and manage to care about him/her anyway?
I think one important aspect of writing with unsympathetic characters is making it clear that the author KNOWS the character is unsympathetic.  Nothing makes me throw a book across the room faster than finding a character that I can't stand but that the author seems to think is great.  (I'm thinking of some of the alpha males in some romance novels, for example - if I'm yelling, "that's rape, you jackass!", the author shouldn't be going on about the character being a dashing rogue.)
Comment: The fact that people (meaning generally women in this case) buy books like that, or are fascinated by guys treating women like crap but secretly being deeply in love with them, is a fascinating issue of psychology that may be more easily approached in fiction than non-fiction. Perhaps some food for thought ...
Answer: As usual, Kate is spot-on. Also, you can make your unsympathetic main character more human and believable by going deep into his head, perhaps even using first-person point of view, to fully explore his motivations. Remember that even Hitler and Stalin did not consider themselves evil. They thought their actions were justified and considered their enemies the evil ones.
Comment: Good point - it's going deep into their heads that can make this kind of character so fascinating!  I already KNOW what it's like to be a relatively well-adjusted, relatively pleasant person.  Having an author help me figure out the motivations of a monster is an adventure!
Answer: Both Kate and Kelly have some brilliant answers. To add my two-cents worth, I agree with both of them. Part of what makes a story so compelling to read (at least, for me) is the character development. Unsympathetic characters, as in your case, make a story interesting, as long as there is some insight into the character's motives and background. And yes, nothing is more frustrating than an author who doesn't know his characters well.
A good example that I have found is in George R. R. Martin's "A Song of Ice and Fire". The characters are beautifully presented. Not a single one is "perfect" and most of them border on downright ruthless. But what made it brilliant was the fact that you understood their motivations, even though you did not necessarily identify with it.
Another great thing is the slight changes in their personality, usually brought about by their interaction with particular scenarios or people. For example, an angry, bitter person "softens up" when he is in the company of the woman he loves. And he knows it. It is the introduction of these slight changes in personality, and what brings them about that allows us to really get to know a character.
I recently watched the movie "Greenberg" with Ben Stiller. His character is highly unlikable and at times I was really frustrated with the way he acted. But after a while he slowly opens up and you get to know what he is really about. It is a good movie with much attention given to the characters. Worth a watch.
Comment: Song of Ice and Fire is a BRILLIANT example!  There isn't a single character in the whole series that I would want to hang out with, but I'm intrigued by almost all of them.
Comment: Do not forget about "Death Is My Trade" by Robert Merle.
Comment: @Kate: I agree with you whole-heartedly :)
Comment: +1 for ASOIAF. Excellent example. I was staggered at the end of Book 4 when I found myself horrified that a particular person was in prison, even though her actions, by any other measure, would have earned her a place there. I wound up sympathizing with several of those family members despite their despicable actions.
Answer: I suppose different people have different tastes. I agree much more with Craig than with Kate.
I haven't read Confederacy of Dunces or any of the other stories mentioned here except Macbeth, so I can't comment on the specifics of those.
Yes, I've read stories and seen movies and so on with heroes who I find totally unlikeable. And I routinely find that I quickly get bored with the story because I don't really care what happens to the hero. If the character is basically a good and decent person, I am cheering him on and wanting him to succeed. But if he is a total villain, I DON'T want him to succeed. He deserves to fail and I want him to fail.
If others find that they can be fascinated by a story about a horribly evil person ... okay. I guess I wouldn't rule out the possibility, but I can't think of such a story that I've enjoyed reading. I think this is quite distinct from a biography of a real evil person, by the way. I might well be interested in a book about Hitler or bin Laden or Blackmun or whomever, but I don't read such a book the same way I read a novel. I'm not getting immersed in the character and wondering what happens next and hoping for him to succeed and so on. I'm reading purely to learn historical facts.
I've read lots of stories where objectively the hero is a very evil person, but the writer is clearly trying to paint him in a way that gets us to want him to win. I find such stories distasteful. Like, I'm supposed to cheer when the serial rapist gets off by pulling that clever legal technicality? Umm, no. I don't like the story and I resent the attempted manipulation. (Note this is not the same as a story where I am supposed to cheer that the villain has reformed himself. I'm talking about the stories where I'm supposed to cheer because the villain got away with the crime.)
That is not to say that a hero has to be a perfect human being for me to be interested in a story. Some of the best fiction is about a person who overcomes his character flaws. And a very common story theme is the "redemption" story -- the character who starts out evil but turns good by the end. Indeed, a hero who is too perfect might be boring because he is too distant from the reader. (Not to mention that a hero who is too perfect becomes difficult to believe. I'm reminded of a really bad movie I saw once where two characters get into a conflict, and they just went so over the top, every step of the way, to make the hero 100% right and the other character 100% wrong, that I just found myself saying, "Oh, come on! He never, ever acted foolishly or got nasty or ANYTHING?")
Answer: I think what really is important is that in the end, the character needs to be useful to the story. Try not to create an anti-hero for the sake of thinking that it would be cool. Try to create characters that will be a good asset to the story's progression and likability. To summarize what I am trying to say is that you need to make sure that the story and environment of your writing piece compliment the characters. For example, a character who is totally evil and crude wouldn't compliment a story that is presented as full on happy and positive, unless if the story has a hidden agenda. Only try and create a anti hero if you think it will actually advance your story.


How to rotate to a target position over time

Question: I know how to do rotations to vectors, but how do I rotate over time?
For instance say I made a function
RotateTo(vec2 iPosition, float iTime);

so it rotates to iPosition over iTime - how would this look? Does anyone know simple algorithm?
Comment: What do you mean by "it rotates to iPosition"? Rotates from where? Around which point?
Answer: If you're in 3D space it really depends on the axis on which you want to rotate. There are indefinite numbers of possibilities when you do not tell your function where it should rotate. With the current function signature there seem to be two possibilities:

you rotate in 2D space
you always want to rotate over the smallest distance

I can only give you a theoretical overview of how rotation can be done. As it seems real game programming uses other methods (see other answers and the comment below my text). However, I guess it still good to know as it is a first principle of rotating.
Rotation over time
Rotation over time is simply a partial rotation each time step. You have to find out about which timespan you want to rotate and which time has elapsed since the last rotation performed. This will require at least 3 variables:

rotation timespan
elapsed time since last partial rotation
angle to rotate

Of course we also need the position the vector is currently in:

vector position

There are now two possibilities I currently see (when using rotation matrices). As I learned, quaternions would be better, because they do not suffer from that much error when doing many small rotations. Yet I think, there also is a method to minimize that with matrices.
There are different ways to go now. The ones I see:

really use the time since last rotation and rotate n times by angle/n degree
remember the time elapsed since you started and the starting position and do the rotation from there. This will eradicate error, as the final position will be like one rotation from the original position.

Let's describe the second method.
You need to have a method that takes:

original vector position
target angle
timespan to rotate
elapsed time since rotation start

Then you can simply rotate by the following formula:
function rotateOverTime(vector, angle, timespan, elapsedTimeSinceStart):
    partialAngle = elapsedTimeSinceStart / timespan * angle;
    rotateZ(vector, partialAngle);

Note that with this method vector will always be the original vector (not taking into consideration the partial rotations) and elapsedTimeSinceStart is the since since the beginning of all your rotations.
The other method is to use the new vector position and onl the time since last rotation, but then you would accumulate error from small rotations and the rotation would not be a nice circle anymore.
Rotation in 2D space
If you want a rotation in 2D space, you actually rotate around the z-axis (because you draw on x- and y-axis). In case your library has a RotateZ function implemented, you can use this. Otherwise, you can use sin and cos.
I do not know it in detail, but it should work something similar to this. Possible that it's not the fastest and most elegant solution:

Calculate the current angle of the vector. This can be done with atan2()
The point around which you want to rotate is usually not (0,0), so you have to move your stuff so that it seems like that was the case (if the rotation center is e.g. (10,10) you have to subtract 10,10 from the point which shall be rotated)
Multiply the new point (=vector; I will use both later, because in algebra you always talk about vectors) with a rotation matrix. I will show in more detail later what this is.
Remove your point to the old location by adding the amount you have subtracted before (here 10).

I hope these images make my math talk a bit clearer ;)
We want to rotate the point (5,5) around (1,2) like the green circle indicates. But with matrices we would rotate around (0,0) as the purple circle shows.

To solve it, we move our point a bit left-down, then we can rotate it around (0,0) and then we move it back again. This moving-around is called translation. Actually my image sucks a bit here, the purple arrow which is going upwards should be the same diagonal as the first purple arrow. Remember, we move our point (-1,-2) down at first and then (1,2) up again. So my arrows are not that well.

I talked about rotation matrix. A rotation matrix is a matrix which you can multiply with your vector to achieve a rotation around the origin (0,0).
cos a     -sin a
sin a      cos a

Where a is the desired angle you want to rotate. This angle is determined by the number of frames you have like Philip has already shown. E.g. if you want it to be rotated in 2 seconds by 90° and 1 second has passed since then, you would rotate it by 1/2 of the total rotation (=45°).
In this case your rotation matrix would look like this:
cos 45°     -sin 45°
sin 45°      cos 45°

Given this matrix, you can multiply it with your current vector to rotate it.
Let's imagine your vector is (5, 7). This would give you (-1.414, 8.485) which is a rotation by 45° counterclockwise.
In case you need a rotation clockwise, you can just adjust the rotation matrix. Either by subtracting your rotation from 360 (e.g. 15° clockwise is 365° counter clockwise) or by using trgonometrical rules.
Let me mention that this always rotates around the origin. Usually you do not want to rotate around the origin in games, because the origin is some random point. In 2D programming it's often the top-left point of either the whole world or the current viewport (camera). Higher level abstractions within your library usually use the image's origin (top-left position), but that's also not what's often desired.
What can we do against this? The magic keyword here is translation and it means moving an object around.
When rotating you have to make sure to move your object to a desired place for rotation, later you can move it back.
Imagine you have a point in 2D at (200, 300) world coordinates. Now you want to rotate it around (250, 250) by 50°. If you would just multiply (200, 300) with the rotation matrix (where you would set a = 50°), the point would be totally of the screen. Instead, move your point so that (250,250) equals (0,0). We would get our current point (200-250, 300-250) = (-50, 50). Now you can rotate this one! After the rotation you move your new point back again (+250).
Rotation in 3D space
In 3D space you can rotate around an indefinite number of axises to reach one point from a given other point. However, the rotation will not always be the shortest. It can require some time to understand this, but just use your left and your right index finger as points in space. Now you can either make a turn upwards, a turn downwards, a turn frontwards, …
Thus we always need to know around which axis to turn when we are in 3D. Generally, you have the base rotations around X, Y and Z axis. Remember we used Z axis for 2D.
Maybe you remember I mentioned something about the shortest distance from the top. Actually, I am not totally sure if this is right, but I think I remember something from my linear algebra classes. According to what I think now, there should always be a shortest distance when rotating in 3D. Only when both vectors are not independant there is again an indefinite number of shortest distances, but let's forget about this for now.
So if you do not have an axis to circle around, but want to determine one, you could go like this:

Calculate the cross product of both vectors (points) => the result is a vector which is independant from both other vectors.
Rotate around the newly vector as axis. This will give you the shortest rotation distance.
Measure the angle between the two vectors (around the calculated axis). Can't tell you at the moment how this could be done, but it's not a hard compuation, you just have to know how ^_^
Normalize this vector (length = 1)
Move your whole scene so that the point around which you want to rotate is the origin (0,0,0)
Use a formula for rotation around axis and angle in 3D
Remove your (rotated) scene back to the former position

Hope I could somehow help you, because it seems pretty difficult to me, but I wanted to explain in detail how rotating works.
Answer: Let's say you wanted it to spin 360 degrees in one second.
Let's also say that iTime determines how many seconds since the function was called.  So if iTime was .01 then 1/100 of a second had passed since the last time the function was called.
Then you would use iTime / 360 to figure out how much rotation you'd need to apply.
Answer: As noted by others, you really don't have enough information there to do what you want.  You need an axis to rotate around, a starting angle, and an ending angle.
However, given all of that, what you want to look up is slerp.  Most APIs and engines will provide the calls you need to implement and construct what you're trying to achieve, but you haven't given enough information in your question to point you at any specific resources.


What's the difference between cross-type autofocus points and regular ones?

Question: What's the difference between different autofocus point types (cross vs point and such)?  Cross points seem to be a "feature" — why?
Answer: Phase-detect autofocus sensors are basically tiny, simple rangefinders — light from each side of the lens is split into two paths, and the two paths are projected onto small linear sensors. The difference between the pattern of light and dark is analyzed, and the amount of front or back focus instantly calculated. (That's why phase-detect autofocus is so much faster than contrast-detection as implemented in most point & shoot cameras — with that, the lens has to seek back and forth to find the point of most contrast.)
If you've used a manual-focus camera with a split-prism in the center of the focusing screen, you can recognize same basic principle at work. As with that, the pattern you're focusing on has to be conveniently aligned against the direction of the split prism for it to be of any use.
A cross-type sensor is simply two linear sensors crossing each other (making a cross shape), which is superior because it can work with both vertical and horizontal light patterns.
In manual split-prism focus aids, it's common to align the split diagonally. This conveniently works with both horizontal and vertical lines/patterns. Some Canon cameras use a diagonal cross for their center sensor. There's other possibilities as well: the Sony A700 uses multiple crossed sensors in a # hash configuration.
Apparently some high-end SLRs use a rectangular autofocus sensor which basically is a small, low-resolution copy of the whole image — more like focusing with a real rangefinder camera, automatically. (Wikipedia tells me this is called "Area SIR", for "area secondary image registration".) That's out of my price range, though.
And, it's worth noting that different sensors can have different sensitivities — more sensitive ones work more precisely at wider apertures, with the trade-off being that they don't work as well with lenses limited to slower apertures. That's covered by a whole different question and answer.
Comment: The EOS 40D apparently has diagonal sensors for the center point: »Additionally the center point is now twice as sensitive as any other point with lenses of F2.8 or faster and has cross-type sensors set at forty-five degrees.« (dpreview.com)
Answer: Cross focusing points focus on contrast changes both horizontally and vertically (2 dimensional focusing) where as normal focus points work vertically only (single dimension).
Cross points give a better chance of locking on to changes in contrast which is how AF works so your AF becomes more effective the more cross points you have.
There is a good article here which explains in more detail about half way down the page:
http://www.cambridgeincolour.com/tutorials/camera-autofocus.htm
Comment: I'm not sure that link is right, as it talks about increased contrast, not phase detection.
Comment: The principle of the cross point remains the same though (whether the method of focus detection is contrast or phase) which is the subject of the question.
Comment: Okay, but what uses contrast-based focus detection with cross-type (or linear) sensors? Don't they usually use a high-pass filter reading from an image sensor?
Comment: Good question :) The phase detection put in lay terms is contrast detection when you boil it down to the very basics I suppose "The difference between the pattern of light and dark is analyzed" the difference between light and dark is the contrast, no?
Comment: I suppose so. :)