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Researchers devise 100x faster way to render realistic metallics

by Mark Tyson on 22 July 2016, 13:01

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The modern world is full of metallic, shiny objects, but future worlds, often portrayed in popular computer games, are often more so. However, up until the current time there has been no way that computer graphics software could realistically portray the 'glints' in shiny metallic surfaces except for in stills. Now thanks to researchers, led by Professor Ravi Ramamoorthi at the University of California San Diego, your metallic graphics in motion "could look a lot more realistic," reports the UC San Diego Jacobs School of Engineering blog. As presented at the SIGGRAPH 2016 in Anaheim, California, Ramamoorthi's new glints rendering method "requires minimal computational resources and can be used in animations".

Don't clean your car with a brillo pad

Summing up the problem in hand Ramamoorthi said "There is currently no algorithm that can efficiently render the rough appearance of real specular surfaces." He added that this situation "is highly unusual in modern computer graphics, where almost any other scene can be rendered given enough computing power."

Current state-of-the-art methods render metallic and similar surfaces incorrectly making such objects "noisy, grainy or glittery" but the new rendering method doesn't assume surfaces are smooth at the pixel level. The new method breaks down each pixel of an uneven, intricate surface into pieces covered by thousands of light-reflecting points smaller than a pixel, called microfacets. Its glint reflection properties are derived from the microfacet angle. Another way of describing the new method is that it "treats a specular surface as a four-dimensional position-normal distribution, and fits this distribution using a mixture of 4D Gaussian flakes". The key to the 100x algorithm speed improvement is said to be in approximating the microfacet angle, saving valuable time and compute power.

Is this scene a little too oily looking?

These glints can be applied to surfaces beyond the aforementioned metals, to shiny fabrics, leather and wood finishes for example (see directly above). A link to the full PDF paper is available here. In addition to Prof Ramamoorthi, study co-authors include; Ling-Qi Yan, from the University of California, Berkeley, Milos Hasan from Autodesk, and Steve Marschner from Cornell University.

HEXUS Forums :: 6 Comments

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And I thought my car was in need of paint correction!

TBH, in games, it's the other end that doesn't feel real. Fabrics - chairs and such.
Really…. they look dreadful (I work with 3D rendering on a daily basis). Metals been able to be ‘faked’ for ages and in most cases actually looks pretty good these days. As above it's fabrics and similar that really needs more work because thats the area which is weakest due to the way texture is done.
I think it's the speed rather than the quality that is exciting here, it's not a bad result, and would probably look much better in motion than a couple of stills.

I do enjoy the occasional articles sprouting out of SIGGRAPH, Hexus should cover more of them.
Yes,it's the detail *whilst in motion* that's important here… in which case, a video would've been nice ;-)
brrr… The submission title for that paper is “Position-Normal Distributions for Efficient Rendering of Specular Microstructure” Then it gets tough.

In any case, SIGGRAPH live streams start shortly. http://s2016.siggraph.org/live-streaming-sessions.