justin solomon
Robust Biharmonic Skinning Using Geometric Fields
Dodik, Ana, Sitzmann, Vincent, Solomon, Justin, Stein, Oded
Skinning is a popular way to rig and deform characters for animation, to compute reduced-order simulations, and to define features for geometry processing. Methods built on skinning rely on weight functions that distribute the influence of each degree of freedom across the mesh. Automatic skinning methods generate these weight functions with minimal user input, usually by solving a variational problem on a mesh whose boundary is the skinned surface. This formulation necessitates tetrahedralizing the volume inside the surface, which brings with it meshing artifacts, the possibility of tetrahedralization failure, and the impossibility of generating weights for surfaces that are not closed. We introduce a mesh-free and robust automatic skinning method that generates high-quality skinning weights comparable to the current state of the art without volumetric meshes. Our method reliably works even on open surfaces and triangle soups where current methods fail. We achieve this through the use of a Lagrangian representation for skinning weights, which circumvents the need for finite elements while optimizing the biharmonic energy.
Wassersplines for Stylized Neural Animation
Zhang, Paul, Smirnov, Dmitriy, Solomon, Justin
Much of computer-generated animation is created by manipulating meshes with rigs. While this approach works well for animating articulated objects like animals, it has limited flexibility for animating less structured creatures such as the Drunn in "Raya and the Last Dragon." We introduce Wassersplines, a novel trajectory inference method for animating unstructured densities based on recent advances in continuous normalizing flows and optimal transport. The key idea is to train a neurally-parameterized velocity field that represents the motion between keyframes. Trajectories are then computed by pushing keyframes through the velocity field. We solve an additional Wasserstein barycenter interpolation problem to guarantee strict adherence to keyframes. Our tool can stylize trajectories through a variety of PDE-based regularizers to create different visual effects. We demonstrate our tool on various keyframe interpolation problems to produce temporally-coherent animations without meshing or rigging.
Geometric Deep Learning: Grids, Groups, Graphs, Geodesics, and Gauges
Bronstein, Michael M., Bruna, Joan, Cohen, Taco, Veličković, Petar
The last decade has witnessed an experimental revolution in data science and machine learning, epitomised by deep learning methods. Indeed, many high-dimensional learning tasks previously thought to be beyond reach -- such as computer vision, playing Go, or protein folding -- are in fact feasible with appropriate computational scale. Remarkably, the essence of deep learning is built from two simple algorithmic principles: first, the notion of representation or feature learning, whereby adapted, often hierarchical, features capture the appropriate notion of regularity for each task, and second, learning by local gradient-descent type methods, typically implemented as backpropagation. While learning generic functions in high dimensions is a cursed estimation problem, most tasks of interest are not generic, and come with essential pre-defined regularities arising from the underlying low-dimensionality and structure of the physical world. This text is concerned with exposing these regularities through unified geometric principles that can be applied throughout a wide spectrum of applications. Such a 'geometric unification' endeavour, in the spirit of Felix Klein's Erlangen Program, serves a dual purpose: on one hand, it provides a common mathematical framework to study the most successful neural network architectures, such as CNNs, RNNs, GNNs, and Transformers. On the other hand, it gives a constructive procedure to incorporate prior physical knowledge into neural architectures and provide principled way to build future architectures yet to be invented.
MIT Adds Professional Education Programs in Machine Learning, AI Transforming Data with Intelligence
Academic programs are one way for professionals to stay current with today's most in-demand skills. With the skills shortage increasing and competition for talent raging through industry and among start-ups, training has become a priority. Many aspiring data professionals are sharpening their skills through online courses or attending industry conferences. However, sometimes you just want to go back to school, at least for a visit. Try the University of Washington or the University of California, Irvine.
Optimal Transport on Discrete Domains
Inspired by the matching of supply to demand in logistical problems, the optimal transport (or Monge--Kantorovich) problem involves the matching of probability distributions defined over a geometric domain such as a surface or manifold. In its most obvious discretization, optimal transport becomes a large-scale linear program, which typically is infeasible to solve efficiently on triangle meshes, graphs, point clouds, and other domains encountered in graphics and machine learning. Recent breakthroughs in numerical optimal transport, however, enable scalability to orders-of-magnitude larger problems, solvable in a fraction of a second. Here, we discuss advances in numerical optimal transport that leverage understanding of both discrete and smooth aspects of the problem. State-of-the-art techniques in discrete optimal transport combine insight from partial differential equations (PDE) with convex analysis to reformulate, discretize, and optimize transportation problems. The end result is a set of theoretically-justified models suitable for domains with thousands or millions of vertices. Since numerical optimal transport is a relatively new discipline, special emphasis is placed on identifying and explaining open problems in need of mathematical insight and additional research.
Universities offer quick-hit studies in AI, machine learning
Organizations are desperate to use advanced technologies to help them gain competitive advantage, get closer to customers and boost the bottom line. In response, colleges and universities are rapidly expanding their course offerings in such topics as artificial intelligence, advanced analytics and machine learning. A prime example is the Massachusetts Institute of Technology, which has announced seven new courses added to its 2018 Short Programs, covering emerging fields and technologies including AI, machine learning, automation, computational design and more. To get a better idea of what is being taught in these programs, Information Management spoke with Lily Fu, director of open enrollment programs at MIT, and Justin Solomon, assistant professor of electrical engineering and computer science at the Computer Science and Artificial Intelligence Laboratory (CSAIL) at MIT. Information Management: What are the "short programs," and how do these new classes relate to what the Institute was already offering in these subject areas? Lily Fu: Short Programs are offered through MIT Professional Education.