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.