CSE 557 Computer Graphics Grail

Winter Quarter 2000

Final Project Artifacts

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Brett Allen & Stefan Saroiu

We developed an animation interface to physical-based modeling of a blast wave impact on surrounding objects. We started with the "Animating Exploding Objects" paper from Graphics Interface 1999 (Mazarak et. al). This paper uses a connected voxel representation of objects to model explosions that result in solid debris. We coined the term "polyvoxel" to refer to a connected voxel object. When an explosion occurs, a blast wave travels through the scene. Each polyvoxel has internal links connecting the voxels. Whenever the pressure exerted by the blast wave is higher than the internal link, the link is broken. If there are no links connecting two or more parts of a polyvoxel, the polyvoxel will be broken into mutiple polyvoxels. Finally to each polyvoxel in the scene a blast force and a torque is applied and their motions are computed using rigid body mechanics.
Cloth Simulation
Will Portnoy & Dan Grossman

With cloth simulation, as in most of Computer Graphics, the challenge lies in making the artifact on the screen look realistic. In particular, the cloth's movements and interactions with its surroundings ought to look familiar to the viewer, who should even be able to recognize different types of cloth simply by watching the simulation's behavior.

In the literature, realistic cloth movement has been obtained using a network of particles connected by springs (in that case, the system is referred to as a mass-spring system) or other natural forces (such as Coulomb forces). With such a model, perturbations at one cloth vertex are propagated to the other areas of the cloth as dictated by the system of differential equations that links the forces acting on all the particles. Thus, local forces -- the result of, say, cloth/object interactions or perhaps the user's dragging of the cloth with the mouse -- and global forces -- such as wind and gravity -- may be applied to the cloth in order to highlight behaviors that will assist the viewer in recognizing the cloth. Then, by changing parameters for the model's force equations, the cloth's reactions can be made to simulate many different types of material.

Justin Goshi & Keneeth Tam

Given 2 source images, we want to transform one to another smoothly through a sequence of intermediate frames.
Automated Calligraphy Using Dynamics
Chris Thompson

I built a software system for creating calligraphic letterforms. The user positions skeleton letters on the screen, uses the user-interface to specify constraints, then finally clicks "Render." The program runs a dynamics simulation to create calligraphic-looking pen strokes, taking into account the mass of the pen and the friction of the pen with the paper. Finally, the program takes the output of the simulation and applies a user-specified rendering style to draw a final image.
Morphing Between Teddy-like Objects
Robert Blanding

Teddy is a sketching interface for 3D freeform design created by Takeo Igarashi. It allows the user to create organic-looking 3D objects from simple 2D sketches. The base-shape for a Teddy object is defined by a 2D polygon, therefore morphing between Teddy base-shapes can be accomplished by morphing between the generating 2D polygons. In order to implement morphing between Teddy-like objects I first implemented functionality for generating the objects from 2D polygons, then integrated this with some of my existing code for 2D polygon morphing.
Simple Fire Model
Eric Hoffman

I implemented the field of gas flow as a smoothed three dimensional noise field interpreted as a vector function, generated in a manner similar to Perlin's Siggraph'85 paper. Since this is graphics and not physics, the matter of primary importance is generating turbulence which looks realistic and connotes fire, rather than exploring the physical behavior of gases. This low frequency noise field is used as force vector to accelerate particles injected at the base of the fire. The smoothness properties of the field provide some continuity between the motion of adjacent particles.
Inverse Kinematics
Karim Filali & Dmitriy Portnov

In this project we implemented inverse kinematics for character modeling. Given constraints for a few end-effectors on the character's body the algorithm constructs the character's joint angles which would try to satisfy the end-effector constraints while ensuring that the character looks "natural".
A C2 Continuous Interpolating Curve with Local Control
Joel Hindorff

In this work I derive and explore a curve that attains each of these three important features, C2 continuity, interpolation and local control, while still only requiring four control points to determine a polynomial segment of the curve.
Comic Shading
Shawn Bonham

The idea behind this project was to model the shading characteristics of cartoon and comic book characters. Traditional shading models such as Phong and Gouraud interpolation give a smooth gradation between light and dark areas, a technique rarely seen in hand drawn animation. To give a more comic feel to rendered objects, a discretized shading model was developed, based in part on Gooch et al.
Dynamic Body Simulation and Tearing
Gerome Miklau & Bart Niswonger

We have simulated dynamic flexible surfaces and volumes (cloths and jello cubes) with a mass and spring system. We then implemented an interactive environment where the user could apply forces to the flexible bodies, and then simulate realistic tearing or breaking of the bodies.
Subdivision Surface
Zhenrong Qian

Subdivision surfaces gain more and more attention from industry and have been widely used in animation production, like "Geri's Game" and "Toy Story II". In the final project, I implement "loop" schema to do the subdivision surfaces.
Cartoon Physics
Jiwon Kim & Karen Liu

We design a simulation environment that combines typical behaviors of cartoon characters and traditional simulations of Newtonian physics.
Nonphotorealistic Shading
Janet Davis

Although traditional computer graphics strives toward photorealism, human-drawn illustrations are often better at conveying geometric information. Much recent work has focused on using technical illustration techniques for automated rendering of 3D models.

My program allows the user to load a model from a text file and rotate the object in real time. The user can toggle shading, edge drawing, and specular highlights. For lighting, I implemented the Phong-shading approximation to Rademacher's model. A single light provides white specular highlights. A simple wireframe technique is used to draw edge lines. I also implemented Gooch et. al.'s method for depicting metal surfaces.
Real-Time Simulation of Rigid Body Dynamics
Charles Gordon

A great deal of work has been done on creating realistic simulations of rigid body dynamics at frame rates. This project attempts to combine the results of a number of different, state of the art algorithms for modelling realistic physics and collisions. The goal was to create realistic approximations to real-world physics while maintaining at least the 30 frames/second needed for animation purposes.