Pixar Shader

Shading Grapes - the basic model

A bunch of grapes is a good case study for our components of contributing illumination. For the shader we used tinting of scatter (with warmth) and lightly-patterned surface diffuse color, allowing more translucency to dominate over the diffuse. Each grape was offset individually from the bunch by a random color shift in hue and value. We also used a subtle diffuse blur and a sharp reflection. With this, the elements were in place for lighting to create an appealing image.

Souce: https://renderman.pixar.com/products/whats_renderman/showcase_ratatouille.html