Materials

Overview

3Delight for Softimage automatically converts Softimage’s render trees (including compounds) into RenderMan shaders and compiles them on the fly. All textures are converted (if needed) into 3Delight’s mip-mapped and tiled TIFF format for efficient rendering and filtering. Material clusters, vertex colors, implicit and explicit projections are all supported. The following material slots are recognized:

• Surface
• Volume
• Environment
• Displacement
• Shadow
• Bump Map

Additionally, the conversion system has been designed in such a way that advanced users can convert their in-house shaders to 3Delight format easily.

Library of supported Softimage and Mental Ray shaders

All the common Softimage nodes are supported and a large set of useful Mental Ray materials is also supported.

Follows a list of all these supported nodes, in alphabetical order.

3Delight's Material Library

In addition to standard Softimage nodes and materials, 3Delight for Softimage comes with easy to use and physically plausible materials. 

3Delight Material – A highly versatile shader to simulate a large variety of surfaces.
Skin – For rendering human skin.
Glass – For rendering glass.

About Physical Plausibility

"Physically plausible" terminology has been first introduced in the computer graphics literature to described a certain category of BRDFs ^[1]. In technical terms, a physically plausible BRDF is a BRDF that:

1. Is energy conservative (e.g. doesn't emit energy that it doesn't receive). 
2. Is reciprocal (respects the Helmholtz reciprocity principle).
3. Doesn't return negative values (this last point is not always mentioned in literature).

In simpler terms, it just means that the BRDF acts as a real life surface would act. 

The expression "physically plausible material" is used in the VFX industry, somewhat loosely, to indicate that the material is based on such BRDFs. In reality, it is very difficult to design materials that are physically plausible since many useful BRDFs are not even energy conservative ^[2]. So it is often more accurate to talk about visually plausible materials.

Physical Plausibility vs. Realism

It's possible to design physically plausible BRDF, respecting the three rules sited above, but still produce images that do not render real life phenomena. In a sense, physical plausibility is not a guarantee of a realistic material. 

Realism in look development is achieved by a mix of sound science, intelligent parameter design and a clear understanding of what is being simulated.  As an example, many available materials provide a choice of BRDFs and an extended choice of parameters. These materials are not suited to render some of the most common real-life objects such as a table or a car. These types of materials are usually coated and it takes a two-layer material and special care to properly render them. Our 3Delight Material provides this possibility.

^{[1] Robert R. Lewis. 1993. Making Shaders More Physically Plausible. Technical Report. University of British Columbia, Vancouver, BC, Canada, Canada.}

^{[2] This is the case because many of the BRDFs rely on lobe-shaped distributions that could go under the horizon for grazing view angles. Most implementation simply ignore this limitation — but strictly speaking, this is an energy conservation problem.}