Introduction to mental ray part-1

mental ray is a general-purpose renderer which creates images of exceptional quality and achieves high

performance through the exploitation of parallelismon bothmultiprocessormachines and across networks

of machines.

The software uses advanced rendering acceleration techniques such as a scanline algorithm for primary

visible surface determination and the BSP (binary space partitioning) algorithm for secondary rays. mental

ray also supports ray classification for secondary rays, and separate shadow ray classification to accelerate

the calculation of shadows, as well as grid acceleration. These algorithms can be fine-tuned by optional usersettable

parameters to achieve even higher performance than normally achieved by the built-in automatic

scene cost analysis.

mental ray supports caustics and global illumination2:1simulation using the Photon MapTM method.

Caustics caused bymultiple reflections and/or refractions, caustics that are themselves reflected or refracted,

and volume caustics are supported. Complete, physically correct simulation of general global illumination

is also supported: any combination of diffuse, glossy, and specular reflection and transmission can be

simulated. For example color bleeding caused by diffuse interreflections, and multiple volume scattering.

mental ray has been designed to take full advantage of parallel hardware, including both thread parallelism

on a single machine, and process level parallelism across networks of machines, and on massively parallel

distributed-memory systems. mental ray takes advantage of thread parallelism automatically; the use of

other machines on the network as render servers may be configured by the user. The renderer balances

the computational load among the available processors using a distributed shared database that distributes

parts of the scene in an optimal way based on demand.

mental ray can be combinedwith any suitablemodeling and/or animation systemvia the .mi file format, or

by integrating the library version into themodeling and animation system, or by combining the library with

a translator that reads the modeling system's native file format. mental ray has been fully integrated into

SOFTIMAGEj3D, and supports all rendering features of Version 3.0, 3.5, and 3.7 for SGI and Windows

NT, as well as additional rendering functionality which is made easily accessible through corresponding

enhancements to the user interface of SOFTIMAGEj3D. mental ray is also the rendering component of

Dassault Syst`eme's CATIA system. Specifically, it is integrated into the CATIA Visualization Studio,

supporting all geometric and nongeometric CATIA entities. mental ray is also available as a plug-in for

Autodesk 3D Studio MAX 3.0. Finally, mental ray is available as a stand-alone program for batch-mode

rendering.

In addition, translators are currently available for AliasjWavefront's Advanced Visualizer, AliasjWavefront

Power Animator, RenderMan RIB, Side Effects' Prisms, IGES, and the DESIRE format.

mental ray is a library for integration into third-party software, as well as for integration in standalone

versions that read a variety of scene formats. In the standard standalone version, input is via a scene file in

ASCII format. The .mi format is the native scene description format of mental ray. Supported geometric

primitives include polygons, and trimmed free-form surfaces. Polygons may be concave or convex and

may contain holes. Displacement maps may be built on top of them.

Free-form surfaces may be input in non-uniform rational B-spline (NURB), B´ezier, Taylor monomial,

or cardinal form, or through the use of basis matrices. Free-form surfaces may be of arbitrary degree.

The geometry of free-form surfaces may be further modified by the application of trimming curves and

displacement maps. Trimming curves need not have the same representation as the surface. Surfaces are

triangulated internally using a variety of available approximation techniques which may be dependent on

or independent of the distance from the surface to the camera.

Connectivity information between free-form surfaces can be given which will stitch surfaces together and

close gaps. If the connectivity is unknown, it can be automatically determined at run-time.

mental ray supports incremental changes to the scene database. Only the parts of the scene that change from