Public Lab Research note


Testing a cheap webcam with Infragram - spoiler alert: nope

by warren |

Read more: publiclab.org/n/16212


We've started shipping some really cheap new webcams with our introductory kits -- the imagery is not great, but we really want to ensure there's an affordable starting point, so we're offering nicer cameras at higher prices. We're doing this with the Lego spectrometer and our new Basic Microscope Kit, I wanted to see if it was possible with the Infragram project. So I gave it a try, removing the lens and substituting a lens with a red filter (turns out these webcams do use an M12 lens mount, of the same kind posted about by @MaggPi).

Here's a plant in the lobby - you can see it reflecting some blue. No white balance, but some

image description

So, over to Infragram.org and I got, using default "red filter and default colormap" -- the below image. Not good; very little highlighting of these otherwise healthy plants. It is indoor but in relatively bright "rainy day" reflected sunlight.

image description

It also didn't really work when I boosted the value using this instead of the standard #ndvi: `((B-R)/(B+R)+.7)`:

image description

So, my conclusion is that this webcam doesn't work too well for this. Maybe on a very bright sunny day it'll be worth another try...

You have to report failures too, or someone else will be doomed to repeat them! :-)



kits webcam infragram infragram-conversion lens red-filter infragram-webcam aren infragram-testing m12 negative-result

ndvi:


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