William Baxter

• Google Inc., United States, Kirkland WA

Shading appearance in illustrations, comics and graphic novels is designed to convey illumination, material and surface shape characteristics at once. Moreover, shading may vary depending on different configurations of surface distance, lighting, character expressions, timing of the action, to articulate storytelling or draw attention to a part of...

We present a new and simple data-driven technique for modeling 3D brushes for use in realistic painting programs. Our technique simplifies and accelerates simulation of the constrained dynamics of brushes by using a small lookup table that efficiently encodes the range of feasible constrained states. The result is a brush model which runs an order...

We define a new shading tool called a Bidirectional Appearance Distribution Function (BADF) tailored to the direct control of stylized appearance. A BADF can be thought of as defining the appearance of a sphere from all possible illumination directions. Our BADF formulation generalizes and improves upon previous stylized shading techniques by enabl...

Project Gustav is a digital painting system that enables artists to become immersed in the digital painting experience. It achieves interactivity and realism by leveraging the GPU to implement our novel art media modeling and brush simulation algorithms. Compared with current digital painting packages, there are two main advances over state-of-the-...

Recent years have witnessed significant advances in 3D brush modeling and simulation in digital paint tools. Compared with traditional 2D brushes, a 3D brush can be both more intuitive and more expressive by offering an experience closer to wielding a real, physical brush. To support popular media types such as oil and pastel, most previous 3D brus...

We present new algorithms for the compatible embedding of 2D shapes. Such embeddings offer a convenient way to interpolate shapes having complex, detailed features. Compared to existing techniques, our approach requires less user input, and is faster, more robust, and simpler to implement, making it ideal for interactive use in practical applicatio...

We present a novel approach to the creation of varied animations from a small set of simple 2D input shapes. Instead of providing a new 2D shape for each keyframe of an animation sequence, we interpolate between a few example shapes in a reduced pose-space. Similar approaches have been presented in the past, but were restricted in the types of inpu...

In this paper we provide a new compact formulation of rigid shape interpolation in terms of normal equations, and propose several enhancements to previous techniques. Specifically, we propose 1) a way to improve mesh independence, making the interpolation result less influenced by variations in tessellation, 2) a faster way to make the interpolatio...

Figure 1: Comparison of conventional toon shading (leftmost image) with our result (remaining images). Edits were made at the three key frames indicated: (left) added shaded area below left eye for expressive impact, (middle) deleted dark area around right eye, and (right) added shaded area below nose to emphasize three-dimensionality. These local...

Recent progress in non-photorealistic rendering (NPR) has led to many stylized shading techniques that efficiently convey visual information about the objects depicted. Another crucial goal of NPR is to give artists simple and direct ways to express the abstract ideas born of their imaginations. In particular, the ability to add intentional, but of...

We present a novel method for solving the incompressible Navier–Stokes equations that more accurately handles arbitrary boundary conditions and sharp geometric features in the fluid domain. It uses a space filling tetrahedral mesh, which can be created using many well-known methods, to represent the fluid domain. Examples of the method’s strengths...

We propose the concept of a latent doodle space, a low-dimensional space derived from a set of input doodles, or simple line drawings. The latent space provides a foundation for generating new drawings that are similar, but not identical to, the input examples. The two key components of this technique are 1) a heuristic algorithm for finding stroke...

We present a new method for controlling kinematic joint chains in animation rigs which addresses significant shortcomings of traditional forward and inverse kinematic systems, combining the best aspects of each while eliminating their respective trade-offs.

Light and shade in the context of non-photorealistic imaging, such as digital cel animation, are semantic notations, rather than physical phenomena. Therefore stylized light and shade should be intentionally animated instead of simulated. This paper proposes an intuitive, direct manipulation method for animating stylized light and shade in real-tim...

We present a flexible modeling approach capable of realistically simulating many varieties of brushes commonly used in painting. Our geometric model of brush heads is a combination of subdivision surfaces and hundreds of individual bristles represented by thin polygonal strips. We exploit bristle-to-bristle coherence, simulating only a fraction of...

The article focuses on computer painting systems. Most technological advances in computer painting systems have focused on the appearance of the resulting images, less on capturing the interaction with the paint materials. The word "painterly" also describes a fusion of feeling, action, sight, touch, intent, and purpose beyond merely producing an i...

We present a viscous paint model for use in an interactive painting system based on the well-known Stokes' equations for viscous flow. Our method is, to our knowledge, the first unconditionally stable numerical method that treats viscous fluid with a free surface boundary. We have also developed a real-time implementation of the Kubelka-Munk reflec...

We present a flexible modeling approach capable of realistically simulating many varieties of brushes commonly used in painting. Our geometric model of brush heads is a combination of subdivision surfaces and hundreds of individual bristles represented by thin polygonal strips. We exploit bristle-to-bristle coherence, simulating only a fraction of...

We present a paint model for use in interactive painting systems that captures a wide range of styles similar to oils or acrylics. The model includes both a numerical simulation to recreate the physical flow of paint and an optical model to mimic the paint appearance.

We present a method for integrating force feedback with interactive fluid simulation. We use the method described to generate haptic display of an incompressible Navier-Stokes fluid simulation. The force feedback calculation is based on the equations of fluid motion, and enables us to generate forces as well as torques for use with haptic devices c...

Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2004. Includes bibliographical references (p. 231-243). Microfiche. s

This paper presents a physically-based, visually-realistic interactive cloud simulation. Clouds in our system are modeled using partial differential equations describing fluid motion, thermodynamic processes, buoyant forces, and water phase transitions. We also simulate the interaction of clouds with light, including self-shadowing and light scatte...

We present a new parallel algorithm for interactive walkthrough of complex, gigabyte-sized environments. Our approach combines occlusion culling and levelsof -detail and uses two graphics pipelines with one or more processors. We use a unified scene graph representation for multiple acceleration techniques, and we present novel algorithms for clust...

We present a survey of our recent research on the development of haptic interfaces for simulating creative processes with digital media, including 3D multiresolution modeling and 2D and 3D painting. We discuss the design issues involved and lessons learned. Based on the preliminary user studies, we observe that haptic interfaces can improve the lev...

We present an algorithm and a system for accelerated display of massive static and dynamic environments using hierarchical simplification. Given a geometric dataset, we represent it using a scene graph and compute levels of detail (LODs) for each node in the graph. We augment the LODs with automatically-generated hierarchical levels of detail (HLOD...