Is a principal researcher in the Graphics Group of Microsoft Research at Microsoft.
D* symbolic differentiation code and geometric modeling and dynamics examples now available for download
The download includes the D* executable and full source code for the following: basic D* programming examples, Lagrangian dynamics, and a basic interactive geometric modeling tool. This is unsupported code but if you find bugs or have feature requests send email to dstarfeedback@live.com. Download here: DStarDownload
Video with example real time dynamics simulations: Dynamics Video
Symbolic Differentiation
Efficient Symbolic Differentiation
Brian Guenter
D* generates symbolic derivatives which can be thousands of times faster than those generated by Mathematica or automatic differentiation. Functions with densely interconnected expression graphs, which arise in applications such as dynamics, spacetime optimization (also known as the optimal control problem), and PRT, can be difficult to efficiently differentiate using existing symbolic or automatic differentiation techniques. The D* algorithm computes efficient symbolic derivatives for these functions by symbolically executing the expression graph at compile time to eliminate common subexpressions and by exploiting the special nature of the graph that represents the derivative of a function. This graph has a sum of products form; the new algorithm computes a factorization of this derivative graph along with an efficient grouping of product terms into subexpressions. For the test suite problems D* generates symbolic derivatives which are up to 4.6×10^3 times faster than those computed by the symbolic math program Mathematica and up to 2.2×10^5 times faster than the non-symbolic automatic differentiation program CppAD. In some cases the D* derivatives rival the best manually derived solutions.
The paper on this website is a revised and expanded version of the paper I presented at SIGGRAPH 2007. I will be updating it as I find the time. (most recently updated 11/1/2007)
Procedural Modeling
Exact Procedural CSG Modeling for Real Time Graphics
Generative CSG models, while having the desirable characteristics of compactness and resolution independence, have never been used for real time rendering because no algorithms existed which could both maintain their compact representation and render them efficiently at run time. The key difficulty in doing this was finding a compact, exact representation of the implicit curve of intersection that arises from CSG operations. The primary contribution of this paper is a new algorithm for finding a piecewise parametric representation for this intersection curve. The parametric representation is compact and exact to the limits of precision of floating point arithmetic. Arbitrary points on the intersection curve can be efficiently evaluated at run time which allows triangulation density to be adapted dynamically. Using this representation we have made complex procedural objects that have a memory footprint of just 7-11 KBytes, which render at approximately 20 million triangles/ sec. on an NVidia 6800 GPU.
Brian Guenter and Marcel Gavriliu
Exact Procedural CSG Modeling for Real Time Graphics
Quicktime video (42MBytes) AVI video (21MBytes)
Face Animation
Making Faces (published in SIGGRAPH 98) with Cindy Grimm, Henrique Malvar, Daniel Wood, and Frederic Pighin
In the video the actress is reading from a script designed to provide maximal phonetic coverage (we were planning to do automatic lip sync as a follow-on research project but never got around to it). Hence the funky monologue.
Quicktime video (164MBytes) AVI video (66MBytes)
Real-time, Photo-realistic, Physically Based Rendering of Fine Scale Human Skin Structure
A. Haro, B. Guenter, and I. Essa, Proceedings 12th Eurographics Workshop on Rendering, London, England, June 2001
http://www.cc.gatech.edu/cpl/projects/skin/index.html
Modeling and
Rendering for Realistic Facial Animation
Stephen R. Marschner,
Brian Guenter, and Sashi Raghupathy
11th
Eurographics Rendering Workshop (2000)
Antialiasing and Compression
Lossless Compression of Computer-Generated Animation Frames (published in Transactions on Graphics, October 97) with Hee Cheol Yun, and Russel M. Mersereau
ACM Transactions on Graphics, v.16, no. 4, October 1997, pp. 359-396
Through an unfortunate sequence of events the original files have been, ahem, misplaced. You'll have to go to the ACM web site to look at this paper.
Quadrature Prefiltering for High Quality Antialiasing (published in Transactions on Graphics, October 96) with Jack Tumblin
Miscellaneous Topics
Efficient Generation of Motion Transitions using Space-time Constraints (published in SIGGRAPH 96) with Charles F. Rose, Bobby Bodenheimer, Michael F. Cohen. wmv video (14 MBytes)
Specializing Shaders (published in SIGGRAPH 95) with Todd Knoblock, Erik Ruf. wmv video (7 MBytes)
Motion Compensated Compression of Computer Animation Frames (published in SIGGRAPH 93) with Hee Cheol Yun, Russell M. Merseareau
Technical Reports
Motion Compensated Noise Reduction For Computer Animation
word document 128KBytes
postscript document 60KBytes
Deus Ex Machina: movie shown at the SIGGRAPH electronic theater
This is a movie made by my graduate students in 1993 when I was an assistant professor at Georgia Tech. I hadn't looked at this video for more than 15 years. It holds up remarkably well and I'm still impressed by the incredible job they did. My contribution was negligible even though I'm listed as a producer on the credits -- the students deserve all the credit. Unfortunately we made some sort of scaling error when we rendered the frames so the entire film came out much darker than we intended (the producer is supposed to make sure that things like this don't happen). When it was shown at the electronic theater the projector was also very dim so it was almost impossible to see what was going on. A few batlike people who could see in the dark complimented us on the film but my students were still terribly disappointed that after all their hard work no one had really seen their film. Now you can see it in all its original glory, and by using the brightness and contrast controls in Windows media player you can largely eliminate the darkness problem. wmv video (31 MBytes) wmv video (4.5 MBytes)
