[PublicLab] Question: Bad NDVI Results from Pi NOIR with Blue Filter (#21117)
notifi...@publiclab.org
Public Lab contributor nstarli just asked a question entitled 'Bad NDVI Results from Pi NOIR with Blue Filter':
Help them by posting an answer here: https://publiclab.org/questions/nstarli/10-08-2019/bad-ndvi-results-from-pi-noir-with-blue-filter
NGB Photo acquired after white balance procedure
NDVI image using the infragram sandbox
NDVI using cfastie colormap
I am taking some images of maize plants using the Raspberry Pi NoIR camera using the blue filter that it is sold with from the rpi website. I have set the white balance (awb_gains) of the camera using the technique in the previous note of pointing the camera at deep blue origami paper and taking those awb settings then setting awb_mode to off and setting the gains to the previously adjusted gains settings using the origami paper. Above is the NGB image acquired (this looks pretty good, plant material is a yellowish-orange color). However, when I run this image through the infragram sandbox and my own NDVI processing code, I am getting bad results, shown below the NGB image.
To give some more information on the setup. We are taking the images indoors under flourescent lights (however we are next to a large sunny window so should be getting IR I think?) and the surface below the plant is dark gray carpet. At first I thought that we did not have enough IR light, however, if that were the case wouldn't all the NDVI values just be equal to 1 or -1? It looks like all the values are in the green and yellow range.
You received this email because you are subscribed to some or all of the following tags: ndvi,raspberry-pi,infragram,infrablue,pi,question:infragram,rpi,raspberry,white,balance,noir,first-time-poster,ndvi-white-balance,infrapi.
Subscribe to all the tags for this post by visiting https://publiclab.org/subscribe/multiple/tag/ndvi,raspberry-pi,infragram,infrablue,pi,question:infragram,rpi,raspberry,white,balance,noir,first-time-poster,ndvi-white-balance,infrapi.
To change your preferences, please visit https://publiclab.org/subscriptions.
Report spam and abuse to: moder...@publiclab.org
Check out the blog at https://publiclab.org/blog | Love our work? Become a Public Lab Sustaining Member today at https://publiclab.org/donate If this email title has an ID in the format #0000, you can reply with the email you use at PublicLab.org and your response will be posted as a comment on the website.