Patrick M. Hanrahan

Patrick M. Hanrahan's work has had a profound impact on the fields of computer graphics and data visualization. He is known for the development of rendering algorithms, used to create realistic images and animations in films, video games, and other applications. Hanrahan also helped refine the concept of shading languages, which are used to specify the visual appearance of 3D objects. Shading languages have become an important tool for applications from video games to architectural design.

Hanrahan was born in 1955 in Milwaukee, Wisconsin before moving to Green Bay as a young child. His father was an orthodontist, and his mother was a social worker. Hanrahan recalls struggling in school until he developed a passion for chess in high school, eventually becoming the state’s high school chess champion. He attended the University of Wisconsin–Madison from 1973, graduating with a B.Sc. in nuclear engineering in 1977. With no experience in computer graphics and having only taken a single computer science class Hanrahan was largely self-taught but was passionate about this emerging field. As he recalls, “I spent one year teaching myself how to program in C and Unix…and then I basically [worked] on implementing every paper in SIGGRAPH up to that time.”[1] Hanrahan continued at Madison with graduate work but took leave in the early 1980s to join the computer graphics lab of the New York Institute of Technology (NYIT), located on Long Island in a converted two-story garage acquired from the former Vanderbilt-Whitney estate. This was one of the leading research centers for computer graphics at that time. At NYIT Hanrahan worked on a modelling system called GEM and an animation system called EM, eventually becoming a manager in charge of 3D systems. In 1985 he left NYIT and returned to Wisconsin to finish his PhD in biophysics before briefly taking a position at the systems research center of the Digital Equipment Corporation.

In 1986 Hanrahan joined fellow Turing award winner Ed Catmull and computer graphics pioneer Alvy Ray Smith at Pixar Animation Studios. Initially he worked on software for the company’s first commercial product, the Pixar Image Computer. When it struggled to find a market, Hanrahan pitched the idea of taking Pixar’s in-house rendering software and selling it as a commercial product. This became RenderMan, a proprietary 3D rendering software that facilitates communication between modeling and animation applications and the render engine that generates the final high-quality images. RenderMan is a structured environment in which elements of the complex render pipeline from geometry to lighting and virtual cameras are simulated, allowing users to create 3D images without intimate knowledge of each element or even of the system being used to render them.

Hanrahan’s team built RenderMan on top of a system previously developed by Catmull along with Loren Carpenter and Rob Cook called REYES (Render Everything You Ever Saw). Hanrahan’s principal contributions were the RenderMan Interface Specification (RISpec) and its Shading Language. RISpec functioned as a standard communications protocol or interface between modeling programs and rendering programs. RISpec supported complex geometric primitives such as quadrics or bicubic patches, rather than requiring the use of a separate modeling application to approximate complex shapes using polygons. Even more revolutionary was RenderMan’s shading language, which allowed for surfaces such as metal, glass, or cloth to be described using a C-like programming language. Users could modify these descriptions to suit the task at hand, rather than relying on RenderMan’s designers to specify all possible values and options. During his time at Pixar, Hanrahan also developed important techniques for volume rendering, which allows a CGI artist to render a 2-D projection of a 3-D data set.

The RenderMan Interface Specification was first published in 1988. RenderMan is still widely used today by Pixar and across the industry. At the time the award was made 44 of the last 47 films nominated for an Academy Award in the Visual Effects category  had relied on it, including Avatar, Titanic, Beauty and the Beast, The Lord of the Rings trilogy, and the Star Wars prequels. Hanrahan is credited for several productions including Tin Toy (1988) and Toy Story (1995). He received an Academy Award for his work on RenderMan in 1993, followed by two additional technical Oscars in 2004 and 2014.

In 1989 Hanrahan joined the faculty of the computer science department at Princeton University, and in 1995 moved to Stanford University where he continues to work today. 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.

Beginning in the 1990s, he and his students extended the RenderMan shading language to work in real time on the newly available technology of graphical processing units (GPUs). The GPU programming languages that Hanrahan and his students developed led to the development of widely used standards, including the OpenGL shading language that revolutionized the production of video games. Subsequently, Hanrahan and his students developed Brook, a language for GPUs that eventually led to NVIDIA’s CUDA. The prevalence and variety of shading languages 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.

Hanrahan has also worked extensively on data visualization, co-founding the company Tableau in 2003. Its products query relational databases, online analytical processing cubes, cloud databases, and spreadsheets to generate graph-type data visualizations. Tableau was bought by Salesforce in 2019 and is widely used in the business intelligence industry.

Throughout his career Hanrahan has been a dedicated educator and mentor, encouraging students to pursue their passions and let them drive their research – a technique he learned from fellow awardee Ed Catmull. As Hanrahan notes, “More than talent or hard work, I have observed that curiosity and passion determine success, and I really advocate for my students to listen to those inner motivations.”[2] Hanrahan has advised over 50 PhD theses. In 2018, he co-founded the Maxwell/Hanrahan Foundation to support scientists, teachers, conservationists and creators whose diverse perspectives enable us to discover new things about ourselves and our world.