ShaderX is searched by EPO

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While googling the net, I found this remarkable piece. This is a patent application from 2010, and from the drawings, it seems that the inventor had the ‘revolutionary’ idea of calculating some adaptive depth bias based on the depth map to improve shadow mapping.

The noteworthy part of the story is, that the official research, the patent clerk apparently turned up my ShaderX4 article from 2006, as can be seen here further down on the page. The page also states that the application has been abandoned. So, maybe the existence of this article has prevented a patent on shadow maps, or at least discouraged the issuer to pursue the application. In either case, let’s hope it stays that way!

We can draw two conclusions from this.

  • Conclusion 1: ShaderX seems to be recognized by the EPO as a source of state of the art.
  • Conclusion 2: If you have an idea, write about and publish it! It doesn’t matter if it is just a blog post. If it can be tracked down, this can prevent a patent on the same idea in the future!

Comments on Advances in Real Time Rendering 2011

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I finally got around to write some comments on this years Advances in Real Time Rendering held at SIGGRAPH 2011. Thanks to the RTR-team for making the notes available. The talk about physically-based shading in Call Of Duty has already been mentioned in my previous post. So, in no particular order:

Rendering in Cars 2
Christopher Hall, Robert Hall, David Edwards (AVALANCHE Software)

At one point, the talk about rendering in Cars 2 describes how they use pre-exposed colors as shader inputs to avoid precision issues when doing the exposure after the image has been rendered. I have employed pre-exposed colors with dynamic exposure in the past, and I found them tricky to use. Since there is a delay in the exposure feedback (you must know the exposure of the previous frame to feed the colors for the next frame) you can even get exposure oscillation!

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The Blinn-Phong Normalization Zoo

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It is good to see how physically based shading is finally gaining momentum in real time graphics and games. This is something I have been advocating for a long time. Developers are spreading the word. I was especially surprised to learn about Call of Duty: Black Ops joining the club [1]. Even a slick 60Hz-shooter with no cycles to spare can afford to do PBS today!

This leads me to the topic of this post, the normalization of the Blinn-Phong specular highlight. Why am I writing about it? It came to my mind recently with the current batch of publications from people adopting physically based shading models. This got me checking the maths again and I compiled a list with normalization factors for different shading models, given here in this post. I would also like to elaborate a little on the model that I wrote about in ShaderX7 [2]. Be aware this post is a large brain dump.

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