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Xiang Li 李翔

PhD Candidate
Outstanding Teaching Assistant
Clemson University
Clemson, SC, USA

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Internship: Optical Flow Facial Wrapping
- Internship Projects
- University of Southern California Institute for Creative Technologies
I interned at University of Southern California Institute for Creative Technologies on May 2020 to Aug 2020. My supervisor was Mr. Kalle Bladin. My job over the summer was extending ICT's the facial wrapping tool "FaceX" and integrating the optical flow into the tool to improve the wrapping quality.
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Optical Flow Facial Wrapping

The FaceX is the ICT's own face retopoloty tool. It wraps a commond morphable face model ICT-FaceKit to face geometries. The FaceX wraps the face mesh to the target face geometies using Iterative Closest Point (ICP) algorithm. I integrated optical flow to the FaceX in order to get more accurate face surface and reduce texture drifting when we blend expressions. Tools & Language: C++, OpenCV, FaceX, and FaceKit.

Unreal Engine: FPS Shooting Game
- Epic
- Shooter
- Toon Tank
I created two shooting game in Epic Unreal Engine 4 to expand my vision in computer graphics. Those two games are majorly created by C++ in Unreal Engine. I've learnt how to move, animate pawns using C++ in Unreal. I exploared different shooting mechanics: shotting with different effects, sounds.
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Toon Tank

I created a Toon Tank game in Unreal. The blue that we can roll around in the world, aim at enemies, and launch projectiles. There are four tower enemies exist at the map which have some basic A.I. where they can ain at the blue tank and kill it. I also added some special effects like smoke, explosions and sound to make the game a little more dynamic and fun.

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Shooting Game

This is an adcanced version of Toon Tank game. Besides the besic movements, shooting, and visual effects, I implemented the enemy A.I. using behavior trees and blackboards. To improve the animations on the player character, I used animation state machines which transited between animations smoothly.
Physically Based Effects

Implemented commn volumetric modeling and rendering algorithms. I mainly learned fields in theory, deep shadow maps, Signed Distance Functions, level sets, pyroclastic spheres, grids, Closest Point Transform, Nearest Point Transform, and Advection schemes etc. These projects were guided by Prof. Jerry Tessendorf.
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Humanoid Avatar

I used csg operations (union, intersection, cutout, and shell) and basic implicit shapes to create a figure that is humanoid which had two legs, two arms, and a head. Deep shadow maps is the ray marching algorithm I used. My humanoid was a standing god with Halo who stood on a turntable and held a bunny in a teapot. (frame resolution: 1920x1080, 120 frames, 360°)

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Level sets

Level set is a special instance of a signed distance function with values on a grid. I implemented the basic level set algorithm to calculate the shortest distance from each grid point to an object on the grid. There are three short level set videos for three different objects which are bunny, teapot, and bunny in the teapot. Both of those level sets have three points lighting scheme. You can found those three videos here: Bunny, Teapot, and Bunny in the teapot.

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Wedges

I created three wedges which are Perlin noise wedge, Pyroclastic Sphere wedge, and Wisp wedge for this project. Each wedge is based on one guide particle, and each frame is a different setting of the indicated parameters (e.g. octaves, frequencies, frequency jumps). Wisp wedge has 5 million wisp dots in each frame. The wedges are here: Noise, Pyroclastic Sphere, and Wisp.

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Advected Refinement: Fluffy Bunny

This time, the Stanford bunny is adveted. The project starts from pyroclastic displacement and then uses characteristic maps as the advection scheme. The frames start with the bunny with no diplacement or advection, and then ramp to displacement magnitude and advection up to full value. The second video is about gridless advection just on the ears of the bunny. Videos: Fluffy Bunny and Ears Advected Bunny.

Physically Based Animation

Those projects were mainly about physically-based modeling for animation and computer graphics. I implemented Particle Systems, Flocking Systems, Flocking, Rigid Body Simulation, and Fluid Simulation. Those projects required implement those scenarios with the knowledge of Calculus, Physics, Linear Algebra, Numerical Methods, and Interactive Graphics. All the programs were written in C++ using OpenGL, GLM, and GLSL to do the graphics and interaction. The projects were guided by Prof. Donald H. House.
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Bouncing Ball: Toy Story

This is a fundamental project for physically based animation class. It contains a box with six sides, but some faces are culled based on view angle. The box is texture-mapped with "Toy Story" wall paper. There is a 3D spherical ball bouncing inside the box. The ball's speed is determined by wind and gravity. There is a triangle under the bottom of the box, and the ball is able to bounce with it as well. To interact with the simulator, users can change the wind speed, ball speed, fraction coefficient, wind coefficient etc. The whole scene is lighted by three point lighting setup.

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Particles System: Fountain

This project extend bouncing ball to a large-scale particle system simulation. The idea is using particles to represent a water fountain. Each particle ball is drawn with billboard technique. I activate the blend functions to blend the alpha channel so that all the particles look more like water. The water fountain has 4 generators. Totally random generator, fountain generator, irrigation generator, and no generator. The water particles can be effected by wind and lights. The water also can be sucked into a vortex.

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Flocking: Finding Nemo

It's time for exploring the deep ocean! The main theme of this project is Finding Nemo. This project simulates the flocking system. There are thousands of fish in the scene. In order to optimize the running speed, I used OpenGL instance to draw a fish once and distribute this fish object to each particle. The group of fish can steer by themselves to avoid spheres. Depending on modes set by users, the fish will circle around the sea, flee away, or school together.

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Springy Structures: Kung Fu Panda

"Everybody was kung-fu fighting! Woo-ha!" Po follows the instructions of the master Shifu and studies so hard so that he can become a real "Dragon Warrior" earlier. Po is made from spring mesh structures. When the program is run, Po will fall off until he hits the "floor", and then he will bounce back and forth. Once Paul settles down, users can turn on the flashing mode, Po will get "Qi" from the universe due to the "Yin" and "Yang".

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Rigid Body: Falling Brick

The rigid body is a cuboid. When the program is run, the cuboid will drop off due to the gravity and will bounce on the floor until it hits the resting position. The rigid body involves point to point, point to face, and face to edge detection. The integration scheme that be used is Runga-Kutta fourth-order.

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Disney Theme clips

This was the final project for the class. I regenerated the Disney opening theme clips, however, the shot was guided by physical principles. The flag on the top of the castle was a spring system. The flag could be blown in wind. The fireworks were particle system, which appeared with random colors and at random positions. The Disney castle was painted in the substance painter. I also choreographed the camera movement so that it matched the original clips.

Ray Tracing

This is self-learning project. I followed the tutorial book "Ray Tracing - The Book Series" written by Peter Shirley. This book is mainly about building a path tracer with C++.
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Ray Tracing in One Weekend

The image on the right side is the final rendering of the book. There are three big spheres at the center of the image, which are a metal ball, difuss ball, and a glass ball. This is a simple brute-force path tracer using randomness for anti-aliasing, reflection, defocus blur, and locations for small balls.

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Ray Tracing: The Next Week

This is the second book of the ray tracing series. The image on the left is the final rendering result. Here I learned how to add textures, volumes (like fog), rectangles, instances, lights, and support for lots of objects using a BVH.

Other Projects

Here are some of my computer graphics related projects which provided me abilities to explore computer graphics in many other areas. I've majorly learnt Maya, Unreal Engine, RenderMan. * * *

Maya Modeling and Animation: Greedy Teddy

This is my first time using Maya so the animation is primitive. However, I modelled the teddy bear from scrach, created the landscape, choreographed the camera cuts, and rendered the animation. The story of my project is Teddy is a greedy boy. He likes all food around world. He will put everything that he sees into his mouth and tastes its flavor! One day he sees a beehive, he thinks he can have a honey feast. But actually it’s full of poison.

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Surfacing: Paragon - Wraith

This is a practice project for Physically Based Rendering(PBR). The main character, Wraith, is from Paragon. The hero asset was painted in the Substance Painter. The tile floor material was designed in the Substance Designer. All the assets were rendered in Unreal Engine with a wider, establishing shot.

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Rendering and Lighting: The Smurf

This is RenderMan rendering and lighting project. I used Mari to shade the smurf surface and imported to RenderMan(Maya shelf tool) 11 for rendering. I set up the HDR background. The lighting shown in the image is the dome lighting.

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RenderMan: Kitchen

This is a practice of how to use RenderMan in Maya 2018. The kitchen scene is from RenderMan Challenge Scenes. I named my final rendering "A cozy afternoon". This is a shot from the kitchen in a cozy afternoon. You are just about to enter the kitchen to grab a cup of coffee. You realize that life is suffering, but at least at this moment, you are able to enjoy your own time alone. The major lighting is dome lighting. I painted this scene using RenderMan materials and substains painter.

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