HDRI with sub-par results in 3

tzframpton · 发表于 2022-7-8 13:42:11

I imported a Revit model and Max prompted me to use the mr Physical Sky with an Exposure Value of 15 to replace the sun light system from Revit, and all was fine. Rendered a couple things and it turned out okay. But I tried a tutorial to use a different HDR map and the background went black on me?

The tutorial also used a Skylight with the "Use Scene Environment" setting checked under Skylight Parameters, in which the house was very dark as if it was dusk. Are there some prerequisites that I'm missing here?

I'll post screenshots of need be. Thanks!

-Tannar

Cad64 · 发表于 2022-7-8 14:08:55

Yeah, screenshots or renders would be good. I think I have some HDR tutorials somewhere. I'll see if I can find them. I don't render much in Studio Max anymore, but I seem to remember there were some hoops that were necessary to jump through when setting up the HDRI.

Cad64 · 发表于 2022-7-8 14:25:06

If your render is coming out dark then you probably need to do some gamma correction to the hdr image. Watch this tutorial: https://www.youtube.com/watch?v=r6mC4uUo4a4. When it gets up around the 9:00 minute mark he talks about how to correct the gamma.

spittle · 发表于 2022-7-8 14:40:34

It's worth noting: say you are trying out different HDRIs in your scene - say both of these could be of a clear blue sky and you may think that you would need to use the same intensity/exposure settings for both.

If the photographer captured the full dynamic range of the scene for both HDR images then this is true.

If they were lazy (or just weren't aware), then they could have heavily clamped out the sun in one of them, or at least clamp one more than the other. The resulting render would be significantly different.

Possible solutions: boost the HDR's intensity. If you're not already, it's best to replace the sun in the HDR with a 3ds max sun (as it's difficult to capture the full dynamic range of a daylit scene in a HDR unless you use ND filters when shooting).

But rendering black is probably something else rather than something linked to exposure or HDR multiplier.

spittle · 发表于 2022-7-8 14:49:44

I should have added - 'some of the time'!

FYI - The HDR Handbook 2 is a really good book on the subject.

[渲染问题] HDRI with sub-par results in 3

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