For the past 8 years, Animal Logic has been using its custom ASH (Animal Logic Shading System) material definition and rendering technology for all film projects within our proprietary pathtracer “glimpse”.

We present a white paper comparing existing suggested solutions for material layeringfrom MaterialX, PRMan, USD/USDShade, MDL and more, and show how our internal solution provides desirable features and solutions absent from other shading solutions and material definition specifications.

We propose for existing Open Source projects to adopt support for true layered shading and hierarchical assignment, and further propose such solutions provide controllable ordering mechanisms to allow these layering mechanisms to adequately handle typical production scenarios and requirements.

Production examples are provided and discussed, and further areas for research are presented.