| Author | Comment | Last activity | Moderation | ||
|---|---|---|---|---|---|
| nedhorning | "Hi kaushalsingh – Ait seems as if you are trying to calibrate the image using a reference target before you calculate NDVI? If that assumption is a..." | Read more » | about 8 years ago | |||
| kaushalsingh | "@nedhorning Hello Ned, I have calculated ndvi using following code in matlab, using single camera without white balancing: red_orig = imread('IM..." | Read more » | about 8 years ago | |||
| zega | "Oh and i suggest using QTI plot (you can zoom into graph data way better then excel, plot traces with just right click/plot) very nice open source ..." | Read more » | about 8 years ago | |||
| zega | "Yes i do, here: FC__long.txt " | Read more » | about 8 years ago | |||
| warren | "Oh, great -- do you have raw data for these as well, like CSVs? " | Read more » | about 8 years ago | |||
| zega | "I will start with long CFL tubes that i just did... Unfortunately i don't have bare tube (diffuser in front/office lights) that might play same ro..." | Read more » | about 8 years ago | |||
| cfastie | "Hi Robert, In this note and comments we were lamenting the lack of replicate spectra of CFL lamps to confirm the information at the Wikipedia page...." | Read more » | about 8 years ago | |||
| warren | "Oh thanks! I believe, but Chris may correct me, that it'd be sufficient to measure a cold long tube fluorescent lamp and compare it to pretty much ..." | Read more » | about 8 years ago | |||
| zega | "@warren , @cfastie I see i'm kinda late to the party, i can offer source verification (you can ship CFL source to me) with 3rd party device, Ocean..." | Read more » | about 8 years ago | |||
| cfastie | "I have one of the first Mobius cameras that Public Lab bought to test. It has the standard lens. I removed the IR cut filter (note) and then after ..." | Read more » | about 8 years ago | |||
| abdul | "Thanks Chris. I'll try adjusting the white balance a bit, and then posting a research note about it. I'll tag you in it. Do you have one of our new..." | Read more » | about 8 years ago | |||
| cfastie | "Abdul, It is possible that the new lens has different coatings which alter the color balance (red:NIR). This might require an adjustment to the cus..." | Read more » | about 8 years ago | |||
| abdul | "@warren @cfastie So I took a new photograph with the adjusted config file, as I had indeed uploaded the wrong one. The photo looks like this when..." | Read more » | about 8 years ago | |||
| warren | "Just wanted also to link to @stoft's input on this question in this comment: As to the RPi camera, it seems to have two "difficulties" which need ..." | Read more » | about 8 years ago | |||
| warren | "Abdul - it looks like the config file you're using is not set up with a corrected white balance. This page has the corrected WB required as Chris ..." | Read more » | about 8 years ago | |||
| cfastie | "The lamp post, the wall, and parts of the tree trunk are all very dark. It is a common artifact that NDVI computed for dark areas of photos is not ..." | Read more » | about 8 years ago | |||
| cfastie | "Abdul, You are correct that all of the things you list could be responsible for the failure to produce a meaningful NDVI image. It could also be du..." | Read more » | about 8 years ago | |||
| spandan1234 | "Hi cfastie, I need a little help here. Following your suggestions I did all the calibrations required and the results were great. But in the last f..." | Read more » | about 8 years ago | |||
| mathew | "Flatfield and scale images: " | Read more » | about 8 years ago | |||
| cfastie | "The spectral response figure came from an article linked in this thread: https://groups.google.com/forum/#!topic/plots-infrared/aJhM30D6bUM That's..." | Read more » | about 8 years ago | |||
| curiousity | "thanks to @cfastie for the interesting charts... How did you take it ? Looking at chart, using just the blue channel as NIR the NIR/VIS sensitivi..." | Read more » | about 8 years ago | |||
| cfastie | "All three Bayer filters (R,G,B) transmit some near IR light. Above: Spectral response of a Canon PowerShot A2200 before (top) and after (bottom)..." | Read more » | about 8 years ago | |||
| curiousity | "You said ...With the red filter we can be fairly confident that the blue channel contains primarily NIR light... But how this happens ? As I know..." | Read more » | about 8 years ago | |||
| warren | "Oh great; @khufkens also shared that on this site! https://publiclab.org/notes/khufkens/11-02-2015/ov5647-raspberry-pi-camera-spectral-response-qua..." | Read more » | about 8 years ago |