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ssec / sift

A visualization application for satellite imagery
http://sift.ssec.wisc.edu/
GNU General Public License v3.0
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vmax on algebraic should be larger than 1 #394

Open gerritholl opened 7 months ago

gerritholl commented 7 months ago

I defined an algebraic as the ratio between two channels (0.91 µm and 0.85 µm). In the layer details, I visualise this algebraic with the colormap "grays", and want to choose the range between 0.5 and 1.1. However, there is a hard limit on vmax set to 1, so it is not possible to set the upper limit to 1.1.

For a user-defined algebraic, there should not be any upper or lower limit to the colormap scale. Or if there has to be, the range could be set to something a bit more than the maximum value occurring in the dataset.

image

Interestingly, if I click "fit to data" I can get the upper limit to be (much) larger than 1.

(I thought I had seen this reported or perhaps even reported it myself; however, I can't find a related issue)

djhoese commented 7 months ago

What were the initial vmaxes of the input bands to your algebraic. In old versions of SIFT I think the min/max was computed by running the inputs vmin/vmax into the code of your algebraic layer and taking the min/max of the results. I'm surprised by what you're seeing.

Otherwise, as a workaround, can you change the test of the slider to 1.1 and hit the Tab key (to go to another cell in the UI) and does it reflect that forced limit value?

gerritholl commented 7 months ago

The input bands both have the range [-0.01, 1.19].

The UI does not let me manually write a number larger than 1.00. When I select my cursor there and type a larger number, the number does not appear.

As a workaround, when I select "Fit to data", the range jumps to [0.13, 3.39], and then it does let me change the upper limit to any value smaller than or equal to 3.39.

ameraner commented 1 month ago

Adding the discussion from EUM Gitlab issue 120: image