

#publiclab meeting, 2013-10-05 19:33:47

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19:33 meeting Meeting started Sat Oct  5 19:33:47 2013 UTC. The chair is btbonval. Information about MeetBot at http://wiki.debian.org/MeetBot.
19:34 btbonval #topic IR camera magicianry
19:37 #info Don: cameras capture red, green, and blue. NDVI = (red channel - blue channel) / (red channel + blue channel); red will represent infrared, blue will represent sort of absorption by the plant
19:39 #info Camera will absorb infrared into the red channel, but camera manufacturers add infrared filters to block out the IR. Remove the filter and red channel will measure some level of IR
19:39 #info Used to measure plant health based on plant's absorption due to photosynthesis (blue channel) compared to reflection of infrared (red channel)
19:41 #info Farmers use NDVI to measure the health of their crops, some projects are working to identify plant species from NDVI.
19:42 #info NDVI is done from the air using airplanes, kites, balloons, to map the plant vegetation and health en masse
19:43 #info Matt: history of PL with IRcams: Jeff did some conversions of cameras to see IR in 2010, Scott wanted to use technology to identify wetlands plant/water boundaries and coastlines.
19:48 #idea how to use IRcams for small scale imagery for e.g. gardens in NYC?
19:49 #info Matt, farmers tend to be expects at small scale, picking up leaves and squeezing stems to judge health so that NDVI doesn't add value
19:50 #idea Ted: what about NDVI for algal blooms?
19:50 #info general agreement that it'd be neat
19:52 #info Don: western mass has a problem with water chestnuts as an invasive species. Don and co went out on canoes and balloons to map the chestnuts; identification worked well in the near IR
19:53 #info Infragram sandbox to process near IR camera pictures, process NDVI, and show them side by side with the IR and blue channels.
19:55 #info code for Infragram sandbox is on github. https://github.com/Pioneer-Val[…]e/infrapix-flask/
19:57 #info Ben Gamari submitted javascript code to process images on the front end
20:00 #info Jeff generalized the hard coded NDVI equation of (IR - B) / (IR +  B) into a mathematical language dubbed Infragrammar that supports channel mixing with arbitrary math supported by Javascript
20:01 #info to make NDVI by hand, type this into Monochrome: (R-B)/(R+B)
20:03 #info supports arbitrary variables in formulas which has a slider to interactively experiment with image output
20:03 #info Hagit asks how to interpret NDVI or any false color images if not using RGB (normal human perception)
20:04 #info Don explains that with a particular NDVI example, colors in the blue range indicate less to no photosynthesis while colors in the yellow and red indicate higher photosynthesis, which indicates thriving vegetation
20:06 #info How can quantitative measurements that determine plant health by correlated to NDVI?
20:07 #idea Ted: perhaps perform experiments on plants with treating plants poorly to get some quantitative idea about plant health measures in a controlled environment and see how NDVI correlates
20:08 #info Cindy: NDVI can be quite different depending on where the sun is in the sky and other ambient lighting conditions such as clouds
20:09 #info Matt: how quantitatively accurate the Infragrams are is a lesser priority to maintaining consistency across all the various hardware and software platforms, given that many infragrameters are DIY
20:09 #info Ted and Cindy have found that two or three cameras flown at the same time can show different NDVI results, as an example of the lack of consistency that should be worked on
20:11 #info Ted suggested having some kind of control color like Mars rovers use in a palette
20:11 #info Bryan discussed grey cards as an example of what photographers do to calibrate light levels
20:12 #info Matt showed a sort of multicolor tile with photographer grey, blue, green, white, black, and a color that should appear black in visual but white in IR
20:14 #info Bryan doesn't think the card would work in flight because it won't capture ambient light of the subject, Matt noted the focal length problem (focus on the card or the ground?).
20:14 #info Bryan suggested that Matt's card would be very helpful for working on small scale experiments and determining consistency between cameras for calibration purposes
20:16 #info Dan would like to use CHDK to lock down camera settings to increase the consistency of shooting many pictures across cameras or across cameras.
20:17 #info Matt finds that NDVI is a quantitative tool that yields qualitative results, which might lead it to say weak generalizations especially in small scale
20:18 #info Dan: what do the big agricultural folks do? what's their capability?
20:18 #info Matt: find locations where there are inconsistencies in an image, then send someone out for closer inspection with other tools
20:19 #info Cindy: farmers in the UK pay a lot of money for satellite imagery of all kinds.
20:21 #info Ned Horning had found object and texture recognition algorithms, but they are difficult for beginners. Don suggests taking them and putting them into the Infragram sandbox would make these analyses much easier and more accessible for the general public
20:26 #info some discussion about insects and other forms of visual perception outside human range
20:26 #info some discussion about IR light sources for night lighting and controlled sources
20:27 #info switching to out of scope spectral workbench discussion and images
20:31 #info The old film negative filter blocked visible light but allowed IR. Two cameras would be needed, one to capture IR and another to capture VIS. The new infrablue film allows blue and IR through while blocking the other wavelengths
20:32 #info switching to physical modification of cameras
20:32 #endmeeting
20:32 meeting Meeting ended Sat Oct  5 20:32:23 2013 UTC. Information about MeetBot at http://wiki.debian.org/MeetBot. (v 0.1.4)
20:32 Minutes: http://meeting.sugarlabs.org/p[…]-05T19:33:47.html
20:32 Log:     http://meeting.sugarlabs.org/p[…]13-10-05T19:33:47

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