I made a couple of NDVI images of the beans which had been greatly improved using compost compared to those grown without. The principles of NDVI as based on that
Generally, healthy vegetation will absorb most of the visible light that falls on it, and
reflects a large portion of the near-infrared light. Unhealthy or sparse vegetation reflects
more visible light and less near-infrared light.
Knowing that, it’s possible to see in the NDVI image that the compost-grown beans do seem to be reflecting more IR relative to visble light, I find this easier to qualify from the greyscale image Continue reading
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 image of something in the polytunnels. Should have made a not of what this plant is 😉 Anyway, more red and going to magenta white overload=more photosynthesis
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