Getting the most out of the premade DS materials you find!
- Generally, bump settings should be changed for the same material to look good in closeup and from a distance: you will want to decrease bump strength for closeups, and the other way around.
- Using displacements for the tiniest level of detail of the material, like individual hairs or skin pores, is not an efficient way of distributing resources. Displacement is a “costlier” operation than bump to calculate, in terms of render time. A rule of thumb could be: if you want the relief to visibly distort the outline of your mesh (like making a cratered moon out of a smooth sphere), then use displacement. Otherwise, use bump. It will make no visible difference with the same strengths and values, but will tend to render faster.
- It is worth turning “trace displacements” on, especially if you are using high values: generally, the increase in render time is not that large with modern hardware, but it will eliminate a lot of weird artefacts in your render that using raytraced effects may produce (including, but not limited to: raytraced shadows, particularly soft shadows and area light shadows; AO/GI). Important: if you are using 3Delight’s “raytrace” hider (whether by checking “progressive mode” in the general DS render settings or via the “scripted renderer”), you have to have “trace displacements” on to actually see the effect (the “raytrace” hider is a pure raytracer, while the so-called “hidden” hider is based on REYES architecture and does displacement via a different algorithm).
- If you are using the “skin” mode of the DS default shader, it will not calculate reflection. So don’t be frustrated if you can’t make it work… because it simply does not.
- While the Ambient channel (of any shader) can be useful for lightning-fast emulation of subsurface scattering or velvet-like backscatter, please remember that it will glow in the dark by definition. So, unless it is precisely your intention, you may want to dial down ambient strength when doing darker scenes (think nighttime) or when using GI (because then ambient will actually illuminate your scene!).
- Do likewise if you find that the material looks too flat or overexposed – you may come across premade materials where ambient is on but serves no real purpose. A rule of thumb may be: if ambient is on, try turning it off (or setting to 0% in the case of shaders like the default DS one) and see if it’s not going to look better.
- Less evident, but mapped reflections will also glow in the dark! In cases of polished metals or other highly reflective surfaces, it may actually look quite realistic in a darker scene.
- Using “Velvet” channels all over human skin is highly debatable. When it’s done, the excuse is that it’s supposed to simulate light being scattered back at the viewer by the tiniest hairs on the surface. But if you look at an average human being, you will not likely find vellus hairs that tiny and that dense for this effect to work, apart from the faces of some women and kids (think “children” more often than “teens”). There is absolutely no vellus hair on the cheeks of a man who shaves his beard; no vellus hair at all on lips, palms or soles. Often, “velvet” is simply used as a substitute for realistic Fresnel specular attenuation. However, “velvet” might work well if you want to render powdered skin.
- You may want to add Fresnel attenuation to reflection and specular so as to make materials like “water” and other dielectric substances (skin, too!) more realistic. This post by John Hable may be particularly helpful in understanding the importance of Fresnel. NOTE: the only precompiled DS shader on the market right now that will attenuate specular is UberSurface2. The original UberSurface or pwSurface2 will only attenuate reflection! However, many materials out there based on the UberSurface will still have Fresnel enabled, even though it does not do anything. You may want to turn it off, so that it would not distract you.