Catmull received his PhD in Computer Science from the University of Utah in 1974. His advisors included Ivan Sutherland, a father of computer graphics and the 1988 ACM A.M. Turing Award recipient. In his PhD thesis, Catmull introduced the groundbreaking techniques for displaying curved patches instead of polygons, out of which arose two new techniques: Z-buffering (also described by Wolfgang Straber at the time), which manages image depth coordinates in computer graphics, and texture mapping, in which a 2-D surface texture is wrapped around a three-dimensional object. While at Utah, Catmull also created a new method of representing a smooth surface via the specification of a coarser polygon mesh. After graduating, he collaborated with Jim Clark, who would later found Silicon Graphics and Netscape, on the Catmull-Clark Subdivision Surface, which is now the preeminent surface patch used in animation and special effects in movies. Catmull's techniques have played an important role in developing photo-real graphics, and eliminating "jaggies," the rough edges around shapes that were a hallmark of primitive computer graphics.

 

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One of Catmull's first hires at Pixar was Pat Hanrahan. Hanrahan had received a PhD in BioPhysics from the University of Wisconsin-Madison in 1985 and had worked briefly at NYIT's Computer Graphics Laboratory before joining Pixar.

 

Working with Catmull and other members of the Pixar team, Hanrahan was the lead architect of a new kind of graphics system, which allowed curved shapes to be rendered with realistic material properties and lighting. A key idea in this system, later named RenderMan, was shaders (used to shade CGI images). RenderMan's functions separated the light reflection behavior from the geometric shapes, and computed the color, transparency, and texture at points on the shapes. The RenderMan system also incorporated the Z-buffering and subdivision surface innovations that Catmull had earlier contributed to the field.

 

During his time at Pixar, Hanrahan also developed techniques for volume rendering, which allows a CGI artist to render a 2-D projection of a 3-D data set, such as a puff of smoke. In one of his most cited papers, Hanrahan, with co-author Marc Levoy, introduced light field rendering, a method for giving the viewer the sense that they are flying through scenes by generating new views from arbitrary points without depth information or feature matching. Hanrahan went on to develop techniques for portraying skin and hair using subsurface scattering, and for rendering complex lighting effects—so-called global illumination or GI—using Monte Carlo ray tracing.

 

Hanrahan published his RenderMan research in a seminal 1990 paper that was presented at ACM SIGGRAPH. It would take five more years, however, for the computing hardware to develop to a point where the full-length 3-D computer animated movie Toy Story could be produced using Hanrahan's RenderMan system.

 

Under Catmull's leadership, Pixar would make a succession of successful films using RenderMan. Pixar also licensed RenderMan to other film companies. The software has been used in 44 of the last 47 films nominated for an Academy Award in the Visual Effects category, including Avatar, Titanic, Beauty and the Beast, The Lord of the Rings trilogy, and the Star Wars prequels, among others. RenderMan remains the standard workflow for CGI visual effects.

 

After he left Pixar in 1989, Hanrahan held academic posts at Princeton and Stanford universities. Beginning in the 1990s, he and his students extended the RenderMan shading language to work in real time on powerful GPUs that began to enter into the marketplace. The programming languages for GPUs that Hanrahan and his students developed led to the development of commercial versions (including the OpenGL shading language) that revolutionized the writing of video games.

 

The prevalence and variety of shading languages that were being used on GPUs ultimately required the GPU hardware designers to develop more flexible architectures. These architectures, in turn, allowed the GPUs to be used in a variety of computing contexts, including running algorithms for high performance computing applications, and training machine learning algorithms on massive datasets for artificial intelligence applications. In particular, Hanrahan and his students developed Brook, a language for GPUs that eventually led to NVIDIA's CUDA.

 

Catmull remained at Pixar, which later became a subsidiary of Disney Animation Studios, for over 30 years. Under his leadership, dozens of researchers at these labs invented and published foundational technologies (including image compositing, motion blur, cloth simulation, etc.) that contributed to computer animated films and computer graphics more broadly. Both Hanrahan and Catmull have received awards from ACM SIGGRAPH, as well as the Academy of Motion Picture Arts & Sciences for their technical contributions.