Mental ray

mental ray is a production-quality rendering application developed by mental images (Berlin, Germany). Mental Images was bought in December 2007 by Nvidia. As the name implies, it supports ray tracing to generate images. Its feature set is comparable to that of PhotoRealistic RenderMan, the RISpec-compliant renderer by Pixar, over which it holds certain advantages and disadvantages. For example, features like global illumination were supported by mental ray long before they could be found in PRman. Which renderer is faster is subject of heated debates: Certain rendering tasks can be much faster in PRman (albeit usually at the expense of true physical accuracy) while others are much faster in mental ray (e.g. computations involving heavy ray tracing or global illumination).

mental ray has been used in endless number of feature films, including Hulk, The Matrix Reloaded & Revolutions, Star Wars Episode II: Attack of the Clones, The Day After Tomorrow and Poseidon.

Features

The primary feature of mental ray is the achievement of high performance through parallelism on both multiprocessor machines and across render farms. The software uses acceleration techniques such as scanline for primary visible surface determination and binary space partitioning for secondary rays. It also supports caustics and physically correct simulation of global illumination employing photon maps. Any combination of diffuse, glossy (soft or scattered), and specular reflection and transmission can be simulated.

mental ray was designed to be integrated into a third-party application using an API or be used as a standalone program using the .mi scene file format for batch-mode rendering. Up to this moment there are many programs integrating this renderer such as Autodesk Maya, 3D Studio Max, AutoCAD, and Revit, Softimage|XSI, Side Effects Software's Houdini, SolidWorks and Dassault Système's CATIA. Most of these software front-ends provide their own library of custom shaders (described below). However assuming these shaders are available to mental ray, any mi file can be rendered, regardless of the software that generated it.

mental ray is fully programmable, supporting linked subroutines also called shaders written in C or C++. This feature can be used to create geometric elements at runtime of the renderer, procedural textures, bump and displacement maps, atmosphere and volume effects, environments, camera lenses, and light sources.

Supported geometric primitives include polygons, subdivision surfaces, and trimmed free-form surfaces such as NURBS, Bézier, and Taylor monomial.

Phenomena consist of one or more shader trees (DAG). A phenomenon looks like regular shader to the user, and in fact may be a regular shader, but generally it will contain a link to a shader DAG, which may include the introduction or modification of geometry, introduction of lenses, environments, and compile options. The idea of a Phenomenon is to package elements and hide complexity.

In 2003, mental images was awarded an Academy Award for their contributions to the mental ray rendering software for motion pictures.

See also

• PhotoWorks, part of SolidWorks which uses Mental ray as its renderer.

Further reading

• Driemeyer, Thomas: Rendering with mental ray, SpringerWienNewYork, ISBN 3-211-22875-6
• Driemeyer, Thomas: Programming mental ray, SpringerWienNewYork, ISBN 3-211-24484-0

External links

Wikimedia Commons has media related to: With mental ray generated images

• My mentalRay
• mental images
• Los Angeles mental ray User Group
• mental ray shaders by Miguel A Santiago
• zDepthDOF shader for mental ray
• Subsurface Scattering tutorial
• mental ray shaders by lamaison
• Maya to standalone mental ray translator by Gonzalo Garramuño
• Open source mental ray shader library by Gonzalo Garramuño
• "German mental ray forum" discussion, help, shader, wiki and many more
• Mentalboutmax Max & Mental Ray Video Training
• mental ray user wiki