SkinLayers material is a three layers SSS dipole implementation in the style of the old alSurface material with added features like ‘peach fuzz’ reflections and ad-hoc params to better control overall sss appearance. Works great for anything releated to subsurface scattering and remains super easy and intuitive to use. Here for this Judge Dredd’s caricature[…]
In our journey on diffuse shading we have seen how a diffuse principled implementation better suites modern workflows than the classical Oren-Nayar implementation. The main offender on the Oren-Nayar implementation (rombo DiffuseGeneralized, Arnold Std Material) is that it is based on single scattering and so it leaks energy (diffuse gets too dark with increasing roughness).[…]
Reflections are a complex matter. However we don’t need to fully understand them to be able to use them in a CG workflow, after all reflection slope for example is just a single parameter we may better grasp just looking at the different results we get while tweaking it. But we can still read the[…]
Because Rombo shading nodes are organized by lobes (diffuse, reflect, sss etc.) we need to choose the right one for the work we gonna do. When we have a metalness map for example we have 3 nodes we can choose from : ReflectGeneralized, ReflectMultiScatter and ReflectFlakes. Being ‘reflect’ nodes the initial setup is of pure[…]
Generally diffuse and specular lobes are layered making use of the Fresnel reflectance at the interface. This simply means that the diffuse lobe is multiplied by 1-Fresnel while the specular lobe is added on top. Practically it means that when Fresnel is at max (at grazing angles) we have only reflections showing up. This ensure[…]
When we generally talk about ‘diffuse’, technically we intend the relationship between surface normals and light direction such that the diffuse model is : N.L. This reads, – N dot L. When we take the dot of two vectors we measure the scalar magnitude between them. Here that means we get the magnitude of the[…]
This shading node does refractions at boundary and then continue the ray into a volumetric medium with single scattering until it hits the back of the surface and it’s finalized into a new direction. This model is generally applicable to materials with low indices of refraction so that their translucent nature implies that a high[…]
This Metallic Paint uber shader is a powerful three layers material able to simulate the complete light transport that happens within the layers. The flakes which are in the middle layer, are multi-scale and BRDF-based (not pattern based) so that at distance they converge to a smooth reflection while at close views they act like[…]
Turns out that most computer graphics conductor materials (metals) don’t fit well with their measured real life counterparts. Looks like microfacet models (any reflection node you ever used..) can’t fully address the appearance of this kind of materials. Microfaceting theory models the appearance of a material at macroscopic level based on surface micro details. Situation[…]
This node basically does multiple scattering refractions. When with romboRefract (or Standard Material) we do engage Scatter in the Refract (transmission) rollout we are doing instead volumetric single scattering. Multiple scattering is slower but more expressive. We can’t really render a resin statuette like this one below with single scattering. Let’s see its main parameters[…]
The SSS Random Walk node is a state-of-the-art subsurface scattering shader. We employ a new sampling strategy for random walks that takes all previouses approaches and put them together for a more effective sampling with reduced render times and great solution quality. Basically what lately did put pathtraced SSS into production is the understanding that[…]
The SSS Dipole shader implements all the relevant dipole models for subsurface scattering available in computer graphics.. namely Standard, Better and Directional dipoles. They are of particular interest because they are better (at matching real life reference materials) than diffusion SSS and way faster than raytraced (random walk) SSS. Let’s see its GUI and main[…]