Alec Rivers
Doctoral student
Computer Graphics Group



Computer Science & Artificial Intelligence Laboratory


Massachusetts Institute of Technology
32 Vassar St., Office 32-D416
Cambridge, Massachusetts 02139
About me
I am a first year graduate student in the Computer Graphics Group at MIT being advised by Prof. Fredo Durand. From 2003 - 2007 I was an an undergraduate at Cornell University, working with Doug James; in the summer of 2007 - 2008 I worked at the University of Tokyo in the Igarashi User Interface Lab; in the spring semester of 2008 I taught computer science at Stuyvesant High School in New York City.
Research interests
I am interested in computer graphics, especially for interactive applications; AI; computer vision; human-computer interfaces; and in any areas where these might overlap. I have done original research in physically-based animation and in sketch-based interfaces.
Publications

Alec R. Rivers and Doug L. JamesFastLSM: Fast Lattice Shape Matching for Robust Real-Time Deformation, ACM Transactions on Graphics (Proc. SIGGRAPH 2007), 26(3), July 2007, pp. 82:1-82:6.

ABSTRACT:  We introduce a simple technique that enables robust approximation of volumetric, large-deformation dynamics for real-time or large-scale offline simulations. We propose Lattice Shape Matching, an extension of deformable shape matching to regular lattices with embedded geometry; lattice vertices are smoothed by convolution of rigid shape matching operators on local lattice regions, with the effective mechanical stiffness specified by the amount of smoothing via region width. Since the naive method can be very slow for stiff models--per-vertex costs scale cubically with region width--we provide a fast summation algorithm, Fast Lattice Shape Matching (FastLSM), that exploits the inherent summation redundancy of shape matching and can provide large-region matching at constant per-vertex cost. With this approach, large lattices can be simulated in linear time. We present several examples and benchmarks of an efficient CPU implementation, including many dozens of soft bodies simulated at real-time rates on a typical desktop machine.

  • Paper (PDF, 5.4MB)
  • Project page (with videos and downloadable demo)
  • Projects

     
    ShareLib
    A shared memory library targeted at simplifying multiplayer game programming. Class project for 6.824.

  • Project page (with video and download)

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    RealMatter
    An early version of the fracturing soft body physics engine targeted at video games.

  • Project page (with videos and downloadable demo)

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    Physical
    A programming library for independent games based on the 2D physics engine.

  • Project page (with manual and download)

  •  
    Physical War
    A side-scrolling action game with fun, fracturing 2D physics.

  • Project page (with download)
  • Sopwith IV
    A remake of the classic "Sopwith" series of games. My first serious project, and still the most complete.

  • Game homepage (with instructions and download)