Kevin Der

About

I'm a first-year computer science Ph.D student at Stanford University and my advisor is Ron Fedkiw. I recently finished undergrad at MIT with a degree in computer science. There I did research with Jovan Popović at the MIT Computer Graphics Group. My research goal is the creation of animation and simulation systems that can create immersive moving images through photorealism and interaction.

Resume [pdf]

Research

Arbitrary Cutting of Deformable Tetrahedralized Objects

Eftychios Sifakis, Kevin G. Der, Ron Fedkiw
ACM SIGGRAPH/Eurographics Symposium on Computer Animation (SCA 2007).

We propose a flexible geometric algorithm for placing arbitrary cracks and incisions on tetrahedralized deformable objects. Although techniques based on remeshing can also accommodate arbitrary fracture patterns, this flexibility comes at the risk of creating sliver elements leading to models that are inappropriate for subsequent simulation. Furthermore, interactive applications such as virtual surgery simulation require both a relatively low resolution mesh for efficient simulation of elastic deformation and highly detailed surface geometry to facilitate accurate manipulation and cut placement. Thus, we embed a high resolution material boundary mesh into a coarser tetrahedral mesh using our cutting algorithm as a meshing tool, obtaining meshes that can be efficiently simulated while preserving surface detail. Our algorithm is similar to the virtual node algorithm in that we avoid sliver elements and their associated stringent timestep restrictions, but it is significantly more general allowing for the arbitrary cutting of existing cuts, sub-tetrahedron resolution (e.g. we cut a single tetrahedron into over a thousand pieces), progressive introduction of cuts while the object is deforming, and moreover the ability to accurately cut the high resolution embedded mesh.

[paper]

[tetrahedron] [sticks]
[slinky] [face]

Inverse Kinematics for Reduced Deformable Models

Kevin G. Der, Robert W. Sumner, Jovan Popović
ACM SIGGRAPH 2006, TOG 25(3), pp. 1174-1179.

Articulated shapes are aptly described by reduced deformable models that express required shape deformations using a compact set of control parameters. Although sufficient to describe any shape deformation, the control parameters can be ill-suited for animation tasks, particularly when reduced deformable models are inferred automatically from example shapes. Our algorithm provides intuitive and direct control of reduced deformable models similar to a conventional inverse-kinematics algorithm for jointed rigid structures. With only a few manipulations, an animator can automatically and interactively pose detailed shapes at rates independent of their geometric complexity. Our resolution-independent metric ensures that even a few vertex constraints generate example-like meshes.

[paper] [slides] [video]

Personal

In my free time, I love watching films and listening to film music. Crossword puzzles are one of my biggest pastimes, and I'm also an amateur crossword constructor. My first published crossword appeared in the New York Times on Monday, March 12, 2007. Let me know if you'd check out this puzzle!

Kevin Der