ARNOLD: With and Without Bitmaps...

quinnredshift — Thu, 29 Aug 2024 17:38:48 GMT

I'm trying to use bitmaps on spheres to make planets; obviously, I'd like water to have a specular highlight and ground to not. And Arnold--bless his frozen little heart--is being really obnoxious about the whole thing.

It looked as though any map having to do with reflection was weirdly offset from the bitmap; you could see highlights on land that should be water and vice versa, but not consistently; it looked like the map I'd made, just...in a different place from the other maps. (I checked the Offset settings, of course.)

So rather than bashing my head against it, I decided to instead just get the parts to be highlighted correct. I fiddled with the Roughness and Metalness settings until it looked right, then made two grayscale bitmaps of the right percent of gray to represent those numerical values and...apparently, it's not a 1:1 scale:

WITHOUT BITMAP

WITH BITMAP

For some reason, it's reflecting the environment when using a bitmap and the highlight is a different size.

Even trying just one of them at a time yields different results.

I know that sometimes MAX and Photoshop don't agree on gamma settings or other things to do with color palettes...could it be that? Maybe 30% gray in PS ain't the same 30% gray in 3DS MAX?

Anyway, I really need consistency, so any help would be appreciated.

Re: ARNOLD: With and Without Bitmaps...

MartinBeh — Thu, 03 Oct 2024 17:11:19 GMT

Not sure this solves your problem but a reflectivity map should not be gamma-corrected, as it is a "data" map and not for direct consumption by a human eye. Same for normal maps, maps used to blend/mix other maps etc.

And Photoshop is pretty "special" about its color spaces and corrections. To help debugging this I would suggest you use a floating point file format such as EXR, just to make sure there is no "clever" code trying to gamma-correct your 8-bit RGB values...

Re: ARNOLD: With and Without Bitmaps...

MartinBeh — Thu, 03 Oct 2024 19:32:12 GMT

Seems to work pretty well?

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ARNOLD: With and Without Bitmaps...

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