Your Avatar May Soon Be Hyperealistic with New Skin Rendering Technique

Friday, February 10, 2012

Graphics researcher Jorge Jimenez has cracked the problem of rendering what he calls "ultra realistic skin" in real-time with consumer-level computer and graphics hardware. It's a breakthrough made possible by the process of separable subsurface scattering (SSS) which quickly renders the translucent properties of skin and its effect on light in two post-processing passes. The code is based wholly on original research using DirectX 10. 

Though Jimenez has released a high definition video of the effect, he's gone two better by releasing downloadable executable demo files that will run on a home PC provided it has a powerful enough GPU, as well as making the source code available on GitHub.

Though the code runs on consumer-level hardware, it'll take more than an everyday PC to run well. On his GeForce GTX 580 equipped machine Jimenez was able to run the demo at a mean of 112.5 frames per second, varying between 80 and 160 FPS. 

The demo consists of a single, stationary head and shoulders - literally a world apart from the dynamic, character-filled environments of modern video games. If the principles are applied to games in the near future, it may be that the results are significantly watered down simply because the graphics processors have a lot more on their plate (unless Attack of the Gigantic Mutant Killer Head from Venus is released any time soon).
If you have a powerful GPU you can download the original demo

And SSS alone is not sufficient for rendering realistic character models. "Efforts towards rendering ultra realistic skin are futile if they are not coupled with HDR, high quality bloom, depth of field, film grain, tone mapping, ultra high quality models, parametrization maps, high quality shadow maps (which are lacking on my demo) and a high quality antialiasing solution," writes Jimenez on his blog. "If you fail on any of them, the illusion of looking at a real human will be broken." The task of rendering realistic skin is especially challenging close up at 1080p, he adds.

For the next steps Jiminez describes:
I think there is still a lot work to do. Probably the most important one will be rendering realistic facial hair. It will be my dream if my skin research helps to improve the rendering of humans in games; I truly believe that more realistic characters will inevitably lead to deeper storytelling, and more emotionally-driven games.
Eyes will also be an important component.  Realistic eye rendering has long been a challenge for capturing accurate digital representations of humans.  Until The Lord of the Rings and Avatar eyes were a tell-tale give-away that characters were computer-generated.  

It's an impressive achievement, and one you can observe in all its HD glory in the video below. According to Jiminez, "This movie represents hours and hours of research, desperation, excitement, happiness, pride, sadness and extreme dedication."