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Author Comment Last activity Moderation
mathew "What happens if you unscrew the lens on the laser and put it in front of the LED? can you concentrate the light to make a brighter point? " | Read more » almost 10 years ago
warren "Hi, Livio - I was so fascinated with your post -- where exactly did you collect a sample from, and was it soil? Water? " | Read more » almost 10 years ago
WhiteRabbit "I found this: http://www.vernier.com/products/sensors/col-bta/ which is interesting because unlike other low-cost spectrometers/colorimeters its s..." | Read more » almost 10 years ago
warren "Wow chris the barcode scanner filter idea is great!!! " | Read more » almost 10 years ago
cfastie "The Public Lab desktop spectrometer is quite capable of making a spectral graph of sunlight reflected from grass. The curve will differ from the pr..." | Read more » almost 10 years ago
WhiteRabbit "Here's a write-up that I'm finding quite helpful: http://publiclab.org/notes/nedhorning/11-01-2013/why-a-red-filter-should-work-well-for-ndvi Eyeb..." | Read more » almost 10 years ago
WhiteRabbit "Sounds like gel filters would be tricky at best, so I guess ixnay to that. How about this one? http://www.ebay.com/itm/Optical-Interference-Filter..." | Read more » almost 10 years ago
stoft "Good observations -- but why use a CFL which has poor SNR for wide-band averaging because the spikes prevent using higher light intensities for bro..." | Read more » almost 10 years ago
cfastie "I have not seen a cheap filter like Rosco that is truly a narrow band pass filter. It might be possible to combine filters to get a fairly narrow t..." | Read more » almost 10 years ago
WhiteRabbit "Cool! Awesome post. I suppose it's wishful (and probably foolish) thinking, but given the the low price of a filter swatch book and the seemingly..." | Read more » almost 10 years ago
cfastie "A filter switcher is a viable solution, especially for small cameras. Cameras as large as Powershots might require a big, precise device in front o..." | Read more » almost 10 years ago
WhiteRabbit "Thanks, Chris, for your thoughtful and very informative post. If I'm reading it right, perhaps using two monochrome cameras, each with the appropr..." | Read more » almost 10 years ago
cfastie "It should be possible to distinguish between stressed and non-stressed lawn grass using NDVI. I suspect that the $900 FieldScout performs more or l..." | Read more » almost 10 years ago
WhiteRabbit "Interestingly enough, I did just now find this $889 turf grass color meter which does, indeed, use NDVI! http://www.specmeters.com/nutrient-manage..." | Read more » almost 10 years ago
WhiteRabbit "Thanks for the links. Supposedly grass also changes color as the soil loses moisture (IIRC, it becomes less green and more blueish?), and people c..." | Read more » almost 10 years ago
warren "I think a lot of the challenge of using an Infragram camera well is the need for comparison. Comparing an area treated in one way with a "control" ..." | Read more » almost 10 years ago
ygzstc "Thanks a lot Jeff! " | Read more » almost 10 years ago
warren "I think i found the data on Yagiz's Spectral Workbench profile, and I made a set: https://spectralworkbench.org/sets/show/1369 Embeds don't seem t..." | Read more » almost 10 years ago
straylight "ah yes, good thinking. well done again on your work, a very well written research note as well. stu " | Read more » almost 10 years ago
ygzstc "Thanks Stu... I just wanted to see if added sugar is detectable first. If yes, you can may be measure the sugar levels during wine making process a..." | Read more » almost 10 years ago
straylight "A rather nice exercise, well done. Quite surprising results I think, I would have predicted the extra sugar to have had minimal effect on the trans..." | Read more » almost 10 years ago
btbonval "I just saw an article about detecting if a drink has been drugged: http://www.gadgetify.com/pd-id-tells-drink-drugged/ How much sugar is in wine? ..." | Read more » almost 10 years ago
warren "Oh I was just hoping for links to the raw data you collected. " | Read more » almost 10 years ago
ygzstc "Info about the spectra is in the appendix already but I guess you mean something different by linking? Am I missing something? " | Read more » almost 10 years ago