My Background

Technical Director, Pixar

Films:Cars, Ratatouille, Wall-E, Up

Shading & Tech Neon shading and LOD (Cars) Set and prop shading (Cars) Crowd Shading/Rendering Pipeline (Wall-

E)

Render Optimization Illumination baking tech, brickmaps

(Cars) Hair Rendering Optimization (Rat) Crowd Rendering Optimization (Wall-E)

Crowd Simulation Massive brain development, pipeline, and

shot work (Rat, Wall-E, Up)

Student, University of Pennsylvania

Digital Media Design Major CS, Math, and Art training

Research Assistant, Human Modeling and Simulation Lab

Rendering Cloth Simulation for Post Doc

Worked on art for paper submissions

Graphics Programming, Color Perception Lab

Hyperspectral rendering pipeline for psychophysics experiments (Radiance, Renderman, and Matlab)

Siggraph Chapter Worked on 3D animations after

class

Lesson Overview

What is RenderMan? Animated Shading

Goal: animating ripening/aging fruit Proceduralism and its advantages Example: Chipped Paint & Rusted Metal Demonstration: Aging Orange

Procedural Pattern Making Creating patterns with fractals Example: Adding dirt to the Orange

What is RenderMan ?

RenderMan™ is a 3D scene description language published and owned by PIXAR Animation Studios. It subdivides into two areas:

The Ri API or RIB The RenderMan™ Shading Language (RSL).

RenderMan is NOT a renderer, it is published standard for renderer’s to adhere to. (e.g. Pixie is a RenderMan renderer.)

RenderMan Concept

[ Saty Raghavachary]

What RenderMan renderers are there?

Photo Realistic RenderMan™ – Pixar – Win, Linux, Irix, Mac OSX - $3500

RenderDotC – DotC Software – Win, Linux, Irix, HP-UX - $ 595 to $2995

Air – Sitex Graphics www.sitexgraphics.com Win –Linux - $450.

3Delight – Win – Linux - Mac OSX – $ 1,000 (First license is free)

Aqsis – Open Source -Win – Linux - Mac OSX - Free

Pixie – Open Source (by Okan Arikan) -Win – Linux - Mac OSX - Free

JRMan – Open Source - Free

Pixar’s Photorealistic RenderMan

We will focus on the Pixar Photorealistic RenderMan implementation (PRMan), and Pixar’s support software: RenderMan Studio (RMS).

Pixar’s RenderMan Products

RenderMan for Maya™ ($995) A Maya plug-in that directly renders Maya scenes using PRMan (much like the Mental

Ray or Maxwell plugins). This product is very easy to learn, but lacks the flexibility and full features of pure PRMan (great for small studios, but not larger productions).   

RenderMan Studio™ ($2,000 - 3500) A suite of tools that provide a customizable render pipeline between Maya and

PRMan. These tools are very flexible and allow access to all of PRMan’s features (great for small to large studios)   

RenderMan Pro Server™ ($3,500) Pure PRMan. It is up to the studio / individual to figure out how to translate their

scenes to RIB/RSL (great for medium to large studios). This is all a renderfarm machine needs. 

PRMan History PRMan was developed by the Computer Graphics

Research Group at Lucasfilm (now Pixar) in the mid 80’s.

PRMan is an implementation of the Reyes rendering algorithm [Cook et al. SIGGRAPH 1987].

Designed for movie special effects and thus had to meet the following criteria:

Extreme visual complexity (hundreds of light sources, millions of polygons, gigabytes of textures).

Seamless integration with live action footage (accurate motion blur / depth of field).

Speed and memory efficient (developed in the 80’s, but still necessary)

History of success, 41 out of the last 44 oscar nominee’s for Best Visual Effects have used PRMan

In 1993, the Academy of Motion Picture Arts and Sciences honored the developers of RenderMan with a Scientific and Engineering Achievement Award for their contribution to the motion picture industry.

PRMan History

RenderMan has been used in a ton of movies. Here's a list:

[ Saty Raghavachary]

PRMan History

What makes RenderMan great? Four things:

1. awesome image quality

2. excellent performance (speed, stability)

3. vast feature set

4. powerful customizability (via shading language, procedural plugins, output drivers..)

[ Saty Raghavachary]

Proceduralism

In computer graphics, “proceduralism” refers to the practice of creating imagery using algorithmic methods rather than solely using stored data from direct artistic input.

In other words, creating art using a recipe, rather than a paint brush or mouse.

Examples: Writing a script to generate a model of a plant

rather than modeling it by hand.

Creating a shading network to combine patterns and images to generate a texture rather than painting it by hand.

[http://en.wikipedia.org/wiki/Procedural_generation]

Pro’s & Con’s of Proceduralism

PRO’s

Detail, procedures can create patterns at any scale without repetition.

Variety, many variations of the same “look” can be created by a single procedure.

Efficiency, a procedure can often create detail using far less memory than if the detail were stored directly.

CON’s

Difficulty, procedural techniques often have a steeper learning curve than more direct methods.

Slowness, a procedure may require more calculations than simply reading stored data.

Fragility, complicated procedures may leave more room for errors and painful debugging.

An application: Ripening Fruit!

Since the fruit and vegetable shaders we are creating for the first assignment are procedural, we can create animation by changing the input parameters to our procedure over time.

We will see how to use our shaders to create to impression of “ripening”.

Application: Aged Materials

• Procedural techniques like aging can apply to many inorganic materials as well:

– Dust– Rust– Chipped Paint– Dirt– Concrete– Brick– Metal

Aged Materials

Aging Demonstration

Dust Example

Full Shading Network

Full Shading Network

Types of Patterns• Procedural: Fractal Noise (slim template)

– Pro: Non-periodic & Seamless– Pro: Infinite level of detail– Con: Limited expressiveness

• Photographs: Texture CD’s– Pro: Physically accurate– Con: Limited detail, periodic.– Con: Difficult to edit

• Generated: Texture Generation (Photoshop Eye Candy, Filter Forge, etc.)

– Pro: Tiling, virtually non-periodic– Pro: More possibilities than noise.– Con: Not as accurate as photographs– Con: Requires HUGE texture sizes.

Application: An Alley

Application: An Alley