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Archive for March, 2017

parallex hair

Fluffy fur used for this helmet.
Polycount Forum thread Fur breakdown.
Image by Joost Vanhoutte.

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Oren Nayar reflection

This post is a complete copy and paste directly from “Renderman Portfolio” All credits go to Kevin George.

Source: https://sdm.scad.edu/faculty/mkesson/vsfx755/wip/best/spring2012/kevin_george/final/index.html

The dielectric shader I created earlier in the quarter afforded me an opportunity to re-learn the relevant computer graphics maths, but was not particularly concerned with physical correctness. My blurry reflection and refraction was just due to a large number of samples in a widening cone around the reflection/transmission direction, with all samples weighed equally. As I have continued my explorations with shading, I have discovered that this is not particularly physically-based, nor is it efficient.

For my independent project, I plan to build on these concepts and create a physically-plausible material along the lines of the mia_material_x (mental ray) material. There are several stages to implementing a shader of this type. First, I plan to implement a number of diffuse and specular models to better understand the underlying maths and practice implementation of a microfacet-based BRDF. Next, I will add reflection functionality, but by importance sampling the specular BRDF instead of the standard cone around the reflection vector.

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