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p-v-o-s / infragram-js

A web application for producing NDVI and other composites from DIY multispectral cameras
http://infragram.org
GNU General Public License v2.0
25 stars 11 forks source link

more control over histogram/colormap scaling #13

Open Fastie opened 11 years ago

Fastie commented 11 years ago

It might make sense to always scale NDVI from -1 to +1. Some results will look wrong, but then it should be possible to modify the appearance either by taking better infrablue photos, changing the formula for NDVI, or scaling the color table.

jywarren commented 11 years ago

I agree with this convention; we did this on the infrapix app.

On Wed, Aug 21, 2013 at 4:31 PM, Fastie notifications@github.com wrote:

It might make sense to always scale NDVI from -1 to +1. Some results will look wrong, but then it should be possible to modify the appearance either by taking better infrablue photos, changing the formula for NDVI, or scaling the color table.

— Reply to this email directly or view it on GitHubhttps://github.com/Pioneer-Valley-Open-Science/infragram-js/issues/13 .

dwblair commented 11 years ago

I believe I've effected this change in the 'colorbar' branch:

https://github.com/Pioneer-Valley-Open-Science/infragram-js/tree/colorbar

Here's the relevant change (hack): https://github.com/Pioneer-Valley-Open-Science/infragram-js/commit/8fbca1147f18b21da60383a533ae49b6f8d49d70

mathewlippincott commented 10 years ago

Really need this feature. My NDVI images are always hovering just above and below 0. some means of scaling is crucial

jywarren commented 10 years ago

Actually I believe Chris was suggesting the opposite, Mathew -- that NDVI be fixed from -1 to +1.

But I think with the site having matured a little, I agree, and see the need for flexibility here; we've been talking a lot about more control over histogram stretching in the Mobius discussions, and need a method for doing that with a slider or an Infragrammar expression or both. I'm going to make the issue name more specific.

If we'd known how much interest we'd be getting in GSoC, we should've promoted Infragram.org more :-/ Oh well.