Maybe I'm not the first to ask this: PBR vs Iray skin materials.

crashworship

What's the difference [between PBR and Iray skin materials]? This may reveal my ignorance but I thought Iray is a physics based rendering engine. So, why would there be the need for PBR vs Iray materials? My assumption, and this could be total BS, is that I'm on a Mac which has an AMD graphics card so, IDK, maybe since Iray is an Nvidia product, PBR materials would work better for AMD cards?

Or, what? I really don't know. I fully expect a "well duh" response to this but so be it. I've used both material presets with my characters and can see no difference in the renders. They look the same.

Ninefold

If what you're asking about is PBRSkin vs. Uber shader presets, both are PBR insofar as, as Iray shader presets, they are presets for a physically based renderer. "PBRSkin" is just a name and doesn't indicate that other Iray shaders aren't PBR. The practical difference is that they offer different functionality and look different in some lights. Use whichever you prefer.

crashworship

Okay, thanks for the clarification. Regarding the lighting, I constantly struggle with photometric lights vs mesh lights. Mesh lighting adds geometry to my scenes but photometric lights give me unsatisfactory results, especially on the warmer end of the spectrum, with noise, graininess and pixilation. I haven't delved too deeply into this with my renders but I generally avoid photometric lighting whenever possible because of this. Very long renders with sometimes really poor results vs mesh lighting. Could this be be what you're referring to? PBR materials working better with photometric lights?

Richard Haseltine

Mesh lights (emissive surfaces) are just lights as far as their properties go, it's just that the light primitives don't have explicit geometry (though if you give them a shape other than point they do at render time). Any difference is in the setings chosen, as far as I know.

crashworship

Richard Haseltine said:

Mesh lights (emissive surfaces) are just lights as far as their properties go, it's just that the light primitives don't have explicit geometry (though if you give them a shape other than point they do at render time). Any difference is in the setings chosen, as far as I know.

This pivots to another question I have, regarding lighting. There are many scene props I have that have a great many lights enabled and with certain characters in those scenes, there's a great deal of noise and pixilation in the render. Especially if the skin skews towards the warmer end of the spectrum. For example, Cleopatra 8.1. If I render her with mesh lights and turn off all the enabled lighting included in the scene prop, she renders fine. Looks great. But if I render her with the scene prop lights enabled, she looks terrible. Grain. Noise. Pixilation. Fireflies. No matter what noise degrain filter setting I use and no matter how long I let the render go, I get all that noise, grain and pixilation. A different character with skin material which balanced towards to neutral of even cooler end of the spectrum won't give me anywhere near as much of all that graininess and pixelation. With either type of characters, mesh lighting always gives me far better renders. I haven't tried to experiment with this but I'm wondering if PBR skin would work better with warmer skin tones? I mean, I could experiment but ya know, time et al?

Richard Haseltine

It may be that the redder look is down to more active scattering or the like, which would give the render more work to do and would be proportional to the number of light sources sending out paths to trace. Generally more light tends to reduce noise, as it fills in out-of-the-way areas that would otherwise rely on the much rarer paths that happened to bounce into them.

crosswind

The more emissive lights there're in the scene, the more grainy noise and fireflies you're gonna have, especially within an interior. Lights bounce among all the emissive surfaces...

You may try: 1) avoid using many emissive lights; 2) limit Max Path Length value in b/t 7 ~ 10; 3) turn emissive lights into ghost lights (latest version); 4) increase render time. 5) denoise in post-work... etc.

crashworship

crosswind said:

The more emissive lights there're in the scene, the more grainy noise and fireflies you're gonna have, especially within an interior. Lights bounce among all the emissive surfaces...

You may try: 1) avoid using many emissive lights; 2) limit Max Path Length value in b/t 7 ~ 10; 3) turn emissive lights into ghost lights (latest version); 4) increase render time. 5) denoise in post-work... etc.

Which is why I turn them off and use one to three mesh lights. Much better light, much less grain and pixelation, much faster render times. But, and I'm not saying that it was a bad addition to Studio, the ghost light scenes now packaged with Studio give me the same noise/grain/pixelation as scenes with a lot of emissive surfaces when the materials, props and people, drift towards the warmer end of the spectrum. If the scene has neutral or cooler shaders, I'm able to use them but for example, a scene with warm skin tone (Cleo 8.1) and maybe a fire prop and they're unusable for me.