Greater Graphics
Chip renders high-quality images in real time

Results: Researchers from Saarland University in Saarbrucken, Germany, have developed a prototype chip that can render desktop computer graphics in real time using a sophisticated technique called ray tracing. Ray tracing produces more-realistic and higher-quality graphics than other techniques, but it previously required a cluster of PCs for real-time performance. Now, the researchers, led by Philipp Slusallek, have shown that a single chip can use ray tracing to render simple scenes at 20 frames per second. (The frame rate for movies, television, and video games ranges from 24 to 30 frames per second.) The chip rendered more-complex scenes at fewer than 10 frames per second.

Why It Matters: The conventional computer-graphics rendering method, called rasterization, doesn’t handle shadows or reflections well, resulting in lower-quality images. Ray-tracing algorithms simulate the physics of light more accurately and make complex scenes look more realistic. But on a single computer, they can take several minutes or even hours to render one image. By implementing the algorithm on a chip, the researchers have provided a way for one PC to do the job in real time, making high-quality rendering cheaper and feasible for home computers.

Methods: The researchers designed a new architecture for their chip that is optimized for the ray-tracing algorithm. They arrived at their design by experimenting with chips called field-programmable gate arrays, which can be reconfigured into different circuit patterns. They then used their chip, running at 66 megahertz, to render 11 different scenes, some taken from computer games and some that were standard scenes used by graphics researchers. They measured such performance characteristics as how many frames the chip generated each second.

Next Step: With the chip’s design finalized, the researchers will use more-standard integrated-circuit techniques to build a new version that can accommodate more processors and render complex scenes faster than 10 frames per second – and that can be cheaply mass-produced. To adopt real-time ray tracing, computer-game programmers would need to slightly change the way they build the graphics for their games.

Source: Woop, S., J. Schmittler, and P. Slusallek. 2005. RPU: A programmable ray processing unit for realtime ray tracing. ACM Transactions on Graphics 24:434-444.