Dizzi, my shader GC materials also anti-GC the incoming color maps. That's not the difference. Well, there is a difference, because bilinear interpolation happens before shader anti-GC, but after render anti-GC, but this is a tiny difference.

I suspect that the reason results are different has more to do with IBL images being anti-GC'd when you enable render GC, and the user is unaware of this.

If you are, for example, using one of my linearized IBL images, made using my GenIBL tool, then that image is already linear when used in Poser 7 or 8. But if you plug that into Poser Pro with render GC enabled, Poser will anti-gamma that image, and it should not because you're using a linear encoded image already.

Similarly, if you're using my environment sphere with IDL as your secondary light source, with 3rd party equirectangular images in JPEG format, my EnvPanoramic shader has a Gamma In and a Gamma Out. Gamma In should be 2.2 if the incoming image is sRGB (i.e. an undoctored photo). But if you enable render GC, then you need to change my Gamma In to 1, and let the renderer do the anti-gamma step.

As to what the Gamma Out should be, the answer is very complicated. It depends on whether or not you're using IDL or not. If you're just using the EnvSphere for reflections, not IDL lighting, then the Gamma Out should be 2.2, unless you're using render GC. Then it should be 1.0.

If you're not using render GC and you are using IDL, then Gamma Out is problematic. There is no single value that's going to be correct both for reflections and for IDL lighting. Furthermore, the issue becomes even more complicated when HSV ETM is used.

On the other hand with Poser Pro and render GC, the setup is trivial and the answer is always the same. Gamma In = 1, Gamma Out = 1, regardless of whether or not you're using HSV ETM and/or render GC. That's part of why render GC makes life simpler. The renderer is handlilng it - no shader hackery.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)