Scene Database

The scene database is the main storage for all scene data that comprise the model to be rendered, including geometry data, the scene DAG hierarchy, light and camera information, as well as material properties and its referenced set of individual shaders and phenomena, and last but not least custom user data.

Geometry

mental ray supports a wide variety of common geometry descriptions as source of input, like surface models based on polygons or triangles, freeform surfaces with trimming curves in several representations, and subdivision surface geometry in hierarchical or plain base mesh form. mental ray will convert such surface descriptions into a renderable representation as needed, known as tessellation, which generates an approximate version of the original surface shape in a certain desired quality, controllable by a set of criteria. It is supported to directly provide the render-time surface representation to mental ray, for applications which perform all the steps like modelling, splitting, and tessellation for rendering already.

Other types of supported geometric entities include curves. They are used for trimming purposes on surfaces, or for specific modelling and rendering algorithms in the form of space curves and hair. Since they don't describe true surfaces they require customized tessellation and shading algorithms to be renderable.

Any other type of source geometry can be implemented with the help of geometry shaders as procedural geometry. For example, a shader may create a surface description from a set of input points only, to reconstruct a shape from a point-sampled model. Typical applications include particle cloud and surface blob rendering based on point data, as well as fluid volume or surface effects from a density field.