The NoIR Raspberry Pi camera comes with a blue filter to do near infrared photography – the blue filter ices the visible red but passes near IR which records as red, apparently.
NDVI (Normalized Difference Vegetation Index) is the near IR plus red divided by near IR minus red. Take a look at this image for the meaning of the colours – red, magenta and white is more photosynthesis, cool colours and black are less. Chlorophyll uses red but doesn’t use near IR which it reflects, hence the difference carries useful information.Lots more at Public Lab. Continue reading