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Question:Can we use a color calibration reference card to calculate absolute values for DIY NDVI?

warren is asking a question about multispectral-imaging: Subscribe to answer questions on this topic

warren asked on October 27, 2017 20:18
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As part of the Infragram project, folks across Public Lab are taking their own DIY multispectral photos to assess plant health. But this work is largely comparative -- since we're using modified consumer cameras, we don't usually know if they're more or less sensitive in one color channel vs. another.

That means we compare imagery, but don't assume that we have an "absolute" measure of NDVI that we can compare across cameras, or in very different lighting conditions.

Anyhow, I've seen some great work by @nedhorning trying to use a standard color reference calibration card to calculate the absolute NDVI, and enable comparisons across different cameras or lighting conditions. How does this work?



near-infrared-camera calibration infragram infragram-point-shoot multispectral-imaging infragram-challenges calibration-card color-reference absolute

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1 Answers

There's a fantastic amount of great information and guidance on this topic by @nedhorning at:

#ndvi-calibrate

Title Author Updated Likes Comparing different filters for making NDVI images using the calibration plugin @nedhorning over 2 years ago 3 Introducing the calibration plugin for ImageJ/Fiji @nedhorning over 2 years ago 6 Automating NDVI calibration @nedhorning over 2 years ago 8 Using a RAW image to calibrate a JPEG image @nedhorning over 3 years ago 4 Improved DIY NIR camera calibration @nedhorning over 3 years ago 7 Calibrating DIY NIR cameras - part 3 @nedhorning about 4 years ago 1 Calibrating DIY NIR cameras – part 2 @nedhorning about 4 years ago 3 a.grid-embed { float:right; padding:8px; } a.grid-embed:hover { color: #888; }


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