I'm trying to understand the behavior of a single laser pulse in a traditional airborne lidar. I understand that the multiple return values are representative of the surface that reflected the initial pulse. However, does a single pulse from the laser, return each reflection individually to the sensor? Or does a single pulse from the laser continue through it's path, capturing each reflection along it's way until returning to the sensor? So if a system can capture 300k pulses per second, are those 300k pulses released and captured? Or is that 100k +/- pulses returning 300k values?  Example photo: Does each disturbance in the waveform return it's own pulse to the sensor? If so, how the sensor understand the laser is continuing? And if that is also true, where does the energy come from to continue the pulse further?
Can someone help with an explanation and some references, in order to understand the nature of return pulses within a LiDAR system.
When is it kosher to delete one's own answer? According to , the only restriction on self-deleting an answer is that you can't delete an answer that's been accepted.  But I've also heard of users getting in trouble for deleting (non-accepted) answers, and there's the CC-SA license to consider, so -- quite aside from what is technically possible -- my question is when it's permitted to delete your own answer.  Some cases to consider:   You now believe the answer is incorrect. Your answer is correct, but another answer covers the same territory better. You aren't satisfied with the quality/rigor of your answer, e.g. it's speculative and you didn't back it up (on a site that expects that). Something in the answer embarrasses you and you'd rather just make it go away. Your answer wasn't well-received by the community (whether that's "meh" or "make the rep bleeding stop please"). (I'm sure there are others; this isn't meant to be an exhaustive list.)   Does voting matter, either in absolute terms or in comparison to other answers?  For example, maybe it's ok to delete a lower-voted one but not the top-voted answer, or one with score > N??  There is a badge, Disciplined, for deleting your own post of score 3 or higher.  This tells me that it's sometimes ok to delete upvoted answers.  But I'm not sure how much policy we can infer from badges.  Could we have some clarification please? Why with two classes, LDA gives only one dimension? Roots of a functionwith condition $\int_0^\pi f(x) \sin x dx = \int_0^\pi f(x) \cos x dx =0.$ Let $f:[0,\pi] \rightarrow \Bbb R$ be a continuous function which satisfies $\int_0^\pi f(x) \sin x dx = \int_0^\pi f(x) \cos x dx =0.$ Show that $f$ has at least two roots. How to schedule a task to run when shutting down windows proof relating to limit definition of e I'm studying the book A Primer for the Mathematics of FinancialEngineering, along with it's solution guide. I've ran into trouble with the solution to question 7 in chapter 1.    The problem is:  Show that $(1+\frac{1}{x})^x &lt; e &lt; (1+\frac{1}{x})^{x+1}$ .   Specifically, I'm having trouble with one step in the solution.    It says that  $$x\ln\left(1+\frac{1}{x}\right)&lt;1&lt;(x+1)\ln\left(1+\frac{1}{x}\right)$$  can be written as   $$\frac{1}{x+1} &lt;\ln\left(1+\frac{1}{x}\right)&lt;\frac{1}{x}, \forall \ge 1.$$  How can the first equality (or is it inequality?) be written as the second? How do split panes in Terminal work? POSTFIX main.cf permission denied I am trying to set up a postfix server for smtp relay. Centos 5.5  I have followed  but am getting a FAILED error when trying to restart or reload postfix.  When I do:  cat maillog   I get:  fatal: open /etc/postfix/main.cf: Permission denied   Here is what I have tried:  chown postfix /etc/postfix/main.cf chmod u+rwx /etc/postfix/main.cf   After that, I do:  ls -l /etc/postfix/main.cf   Which gives me:  -rwx------. 1 postfix anotheruser 27531 Apf 29 12:19 /etc/postfix/main.cf   No dice. Same error. I even tried temporarily doing chmod 777 but got same error.  Any ideas on the permissions problem? I am assuming it is running the service as the postfix user.  Thanks Why are imported PDFs blurry in InDesign? Is there a way to change the process group of a running process? Is there a way to change PID, PPID, SID of a running process? It would make sense for the answer to be no, but I'd like to make sure. As made clear in update 3 on , this notation: var hash = {}; hash[X]  does not actually hash the object X; it actually just converts X to a string (via .toString() if it's an object, or some other built-in conversions for various primitive types) and then looks that string up, without hashing it, in &quot;hash&quot;. Object equality is also not checked - if two different objects have the same string conversion, they will just overwrite each other. Given this - are there any efficient implementations of hashmaps in JavaScript? (For example, the second Google result of  yields an implementation which is O(n) for any operation. Various other results ignore the fact that different objects with equivalent string representations overwrite each other. I'm looking for a single word, for someone who...   keeps seeing everything that is wrong with everybody else.  never seems to see the good of other people, only the bad things. points at others, as if he forgets he has weaknesses himself. does not brag about himself, he just seems to be dissatisfied with everyone else.   I prefer a word that is as unambiguous and clear-cut as possible. How do I rollback a TFS check-in? I'd like to rollback a change I made recently in TFS. In Subversion, this was pretty straightforward.  However, it seems to be an incredible headache in TFS: Option 1: Get Prior Version  Manually get prior version of each file Check out for edit Fail - the checkout (in VS2008) forces me to get the latest version  Option 2: Get TFS Power Tools  Download Team Foundation Power Tools Issue rollback command from cmd line Fail - it won't work if there are any other pending changes  Option 3: Manually Undo Changes  manually undo my changes, then commit a new changeset  Question How do I rollback to a previous changeset in TFS? Version of the app: 1.0.51. (It is up to date at the time of writing according to Google Play.)  This started happening after the network problem that happened earlier this morning. Both my tablet and my phone are popping up notifications for events (comments, and probably edits too) that happened prior to the network issue. I had received notifications for these events already and had already cleared them before the network issue happened.  The repeated notifications do not show up in the bar displayed at the top of the Stack Exchange sites. In other words, I get notified again in Android but do not get notified again on the SE web sites. Full List of inventory items After beating the game, I still have several empty inventory spots.  I most likely missed several items in my addicted frenzy to finish the game.  What are all the items that can be found in the game? And where can they found? Proving $\frac{x}{y} +\frac{y}{z} + \frac{z}{x} \ge 3$ for positive $x,y,z$ Suppose $x,y,z$ are real positive numbers, prove that: $$\dfrac{x}{y} +\dfrac{y}{z} + \dfrac{z}{x} \ge 3$$ with equality when $x=y=z$.  Can someone help me find an easier solution? I started with assume only two are equal, without loss of generality, $x=y$. Then we get $$1 + \dfrac{x}{z} + \dfrac{z}{x}$$ $$1 + \dfrac{x^2 + z^2}{xz} = 1+ \dfrac{(x-z)^2 + 2xz}{xz} = 1 + 2 + \dfrac{(x-z)^2}{xz} \ge 3$$ To prove the general result I considered using a derivative with respect to $y$ to show that, starting with $x=y$ and increasing $y$ by a tiny amount, will show the equation's derivative as positive. I haven't gotten this to work yet. Any ideas? Deriving a QM expectation value for a square of momentum $\langle p^2 \rangle$ I already derived a QM expectation value for ordinary momentum which is: $$ \langle p \rangle=  \int\limits_{-\infty}^{\infty} \overline{\Psi}  \left(- i\hbar\frac{d}{dx}\right) \Psi \, d x $$ And I can read clearly that operator for momentum equals $\widehat{p}=- i\hbar\frac{d}{dx}$. Is there an easy way to derive an expectation value for $\langle p^2 \rangle$ and its QM operator $\widehat{p^2}$? Understanding dummy (manual or automated) variable creation in GLM Change installed AppleScript version Java Generics: List, List, List Can someone explained, as detailed as possible, the differences between the following types?  List List&lt;Object&gt; List&lt;?&gt;   Let me make this more specific. When would I want to use  // 1  public void CanYouGiveMeAnAnswer(List l) { }  // 2 public void CanYouGiveMeAnAnswer(List&lt;Object&gt; l) { }  // 3 public void CanYouGiveMeAnAnswer(List&lt;?&gt; l) { } I am a Bangladeshi citizen. Back in 2013, I went to India with a tourist visa and overstayed for four days. It was due to a gout attack in my feet but I don't have my medical papers to prove that.  I applied again in 2015 for a visa, at Dhaka, and they refused my visa and blacklisted my passport, writing some numbers and date on it. Now I am not able to get an Indian visa.  How I can remove my passport from the blacklist and get a new Indian visa? Do I need a Indian immigration lawyer to do this?