Public Lab Research note

Doing NDVI in one camera

by mathew | September 06, 2012 16:29 06 Sep 16:29 | #3668 | #3668

This company LDP LLC sells converted IR and UV cameras that are being used by Conservation Drones. What really piqued my interest is that they claim to do UV, IR, and visible light in one camera, and sell one-camera NDVI rigs. How? I can't quite tell-- they remove and replace the filters with custom ones, and then I think, based on their conversions page, that it has something to do with the white balance settings.

They're doing NDVI post-processing in ImageJ, a java library for image processing.


Except for the fact that their web site is more confusing than the plot of Lost, MaxMax is a really interesting company. The trick to the one camera NDVI is special filter that they apparently have custom-made (I think by Schott). The filter replaces the IR block filter in the camera. It passes IR and blocks all visible red. So the red channel captures only IR light and the blue channel captures normally. To calculate NDVI, they use the blue channel (light that plants use for photosynthesis) for visible light, and the red channel for IR (light that plants reflect). It is perfectly legitimate. As far as I can tell, Schott does not sell this filter as part of their extensive line of filters. So you have to pay MaxMax $725 for a converted Powershot. If all you wanted was aerial NDVI, this is a smart way to get it because you have to fly only one camera (no shutter sync), and there is no registration of images to do afterwards. But you do not get a normal RGB image.

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