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StrokeStrip: Joint Parameterization and Fitting of Stroke Clusters

Written in collaboration with Chenxi Liu, Nicholas Vining, Mikhail Bessmeltsev and Alla Sheffer.

ACM Transactions on Graphics, August 1, 2021

Artist-drawn vector sketches use clusters of strokes to convey intended curves. StrokeStrip fits intended curves to such clusters by computing and utilizing a joint arc length parameterization of each cluster, producing clean lines consistent with viewer expectations.

We observe that viewers perceive stroke clusters as continuous, varying-width strips whose paths are described by the intended curves. An arc length parameterization of these strips defines a natural mapping from a strip to its path. We therefore recast the curve fitting problem as one of parameterizing the cluster strokes using a joint 1D parameterization that is the restriction of the natural arc length parameterization of this strip to the strokes in the cluster.


Differentiable Shadow Rendering

Written in collaboration with Jerry Yin.

April 14, 2020

We propose a differentiable formulation for soft shadows, allowing optimization of rendered images that include soft shadows with respect to scene parameters.

Our implementation enables applications such as optimizing a model with respect to its shadow. An example task motivating this work is the algorithmic generation of shadow art, in which a 3D shape produces different artist- specified shadow shapes when lit from different angles. An example of shadow art can be found on the cover of the book Gödel, Escher, Bach. Our goal is to find a reasonable tradeoff in this optimization task between visual quality and performance.

Locomotion of Boneless Creatures with Distributed Control

Written in collaboration with Tim Straubinger.

April 14, 2020

We are interested in exploring how plausible it is to control creatures whose bodies contain muscle and no bone.

Given various elastic and deformable body plans, we would like to see what gaits emerge based on body shape and body material properties. Through experimentation, we comment on the effectiveness of genetic optimization over policy gradient optimization, and the expressive capability of local controllers with limited views of the world compared to single, comprehensive controllers.


Automatic Secondary Motion with Dynamic Kelvinlets

Written in collaboration with Jasmeet Singh.

December 1, 2019

Given only primary motion skeletal animation, squash and stretch, overshoot, and jiggling are added automatically in real time.

Dynamic Kelvinlets model the time-varying elastic deformations of objects in response to input forces. Pixar uses them to add an extra level of realism to animations by introducing a secondary motion. We implement a system to automatically apply Dynamic Kelvinlet deformation to achieve visually plausible secondary motion at real-time simulation rates.

Controlling procedural modelling interactively with guiding curves

Written in collaboration with Abhishek Madan, Andrew McBurney, Paul Bardea and Tammy Liu.

Proceedings of Graphics Interface, March 28, 2019

A method of interactive procedural model searching, written for my fourth year research project.

We present a likelihood function for Sequential Monte Carlo sampling that lets artists draw guiding curves to control the output of generating grammars. This framework enables the high-level structure of models to be intuitively specified while allowing for sufficient variation in the low-level details. Our method can be computed at interactive rates to enable the short feedback loops required for exploratory design.


The Engulfed Cathedral: CS488 final project

July 25, 2018

A raytraced 3d renderer and short animation created with it for Waterloo's computer graphics course.

I used this project to implement graphics techniques such as photon mapped lighting, ambient occlusion, volumetric materials, constructive solid geometry, and inverse kinematics, along with sampling methods for inverse procedural modelling.


Frontier: Programming Generative Art

June 14, 2015

2D procedural landscape generation.

I make use of Perlin noise for terrain generation and describe how to think about breaking complex shapes into recursive fractal-like structures to generate trees and houses.