That indeed is very true.zeitmeister wrote:Why does it look more realistic? It looks more homogenous, but is that realistic?
There was a kind of similar thread some time ago on CG-Society. And someone stated there that unless you have a real world example to compare it to it it sort of impossible to say whats realistic.
Thanks a lot for the comparison. This is something that was on my agenda too.Oscar J wrote:Interesting comparisons.
Rendering a glossy transparent object in a uniform environment is a good way to make sure they follow the laws of energy conservation. As you can see Indigo (CPU) renders the glossy transparent monkey pretty much exactly homogeneously with the uniform background. As does Maxwell, after a very long rendering time, at least fairly close.
I agree with zeit that I don't think the Maxwell one looks more realistic. To compare apples to apples you should probably compare Indigo CPU with Maxwell CPU though, as Indigo CPU has virtually infinite path depth, while the limited path depth of Indigo GPU probably affects its appearance (see the darker edges in your render). Would also be interesting to see how Maxwell GPU compares.
P.s. I should have mentioned that I did a bunch of test behind the curtains. Also including comparing Indigo CPU to Indigo GPU. As Zom-B states further down. While CPU is a tid brighter besides that there is no difference in look (definitely the same algorithm was used for both CPU aswell GPU.
I can do a render with Maxwell GPU. Due to the really narrow ray depth (of 8 as stated above) it definitely will look different. I consider Maxwell GPU to be in sort of alpha stage at the moment. Indigos GPU progress is way ahead here.
Thanks a lot for your test! I have attached some more below to further fuel the discussionZom-B wrote:Exactamundo!
In the provided scene we have a lightsource from the left, the frosty dragon could act like a magnifying glass and bundle the light from that side.
Here a long CPU rendering of that dragon (20kspp), where you see that its even brighter then on GPU!
As stated above. Without a real world sample or "example" to match it against is impossible to tell.
I think the reaction that Maxwell is more realistic comes from the following fact:
The rougher the glass the more rays get diffused (dispersed). The more rays get diffused (when entering and also when leaving the material) the more uniform it will look because to form a magnifying lens effect you need rays that are more parallel rather then rays that travel in a very chaotic manner.
I am however not saying that Indigo is unrealistic. Since shaders represent an "assumption" on the surface structure both maxwell and indigo might be correct dependent on the treatment of the glass surface maybe.
I will edit this post later this evening with some more tests:
The dragon renders with 0, 0.25, 0.5, 0.75, 1 roughness.
For Indigo CPU, GPU and Maxwell CPU, GPU