LookupTex POP colors outside 0-1 range

POPs
1

Hi ii’m working with the LookupTex POP and one issue that took me a while to understand was the coloring method.

In this example, the coloring is very straightforward. Close to field has value 1, far is value 0. Value to 0 is white, Value to 1 is Green.

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Now when applying it to this sphere, values on the 0 side seem to wrap around to the green again, but not all the way? This was making it really hard to visualize where the field point was.

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Same thing with a different palette,
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until I noticed that if I turn the interpolation off, it behaves the way I expect.
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In the first example with the head, interpolation is still on though… I thought maybe the field was making the values negative or something so maybe that was why they’re interpolating. But I tried a limit POP with a bunch of different settings.

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But from what I can tell, there’s no reason these points should have negative value. So my question is why are they interpolating?

Here’s my file if anyone can help.
testbed.4.toe (6.1 KB)

2

Hello @ButchBangher
I looked at your sample. With interpolation enabled, when the Lookup Texture POP samples the TOP at UV [0, 0] for Weight zero, it mixes the value between the first pixel and the extended pixel value on the left (the first pixel center is not U zero but 0.5 / width). You have Input Extend Mode set to Repeat. That’s why you get a mix between red and white. If you change the Input Extend Mode to Hold, you’ll get red only.

3

Ahh, okay understood, thank you for explaining!