Variational Autoencoders for Deforming 3D Mesh Models

3D geometric contents are becoming increasingly popular. In this paper, we study the problem of analyzing deforming 3D meshes using deep neural networks. Deforming 3D meshes are flexible to represent 3D animation sequences as well as collections of objects of the same category, allowing diverse shapes with large-scale non-linear deformations. We propose a novel framework which we call mesh variational autoencoders (mesh VAE), to explore the probabilistic latent space of 3D surfaces. The framework is easy to train, and requires very few training examples. We also propose an extended model which allows flexibly adjusting the significance of different latent variables by altering the prior distribution. Extensive experiments demonstrate that our general framework is able to learn a reasonable representation for a collection of deformable shapes, and produce competitive results for a variety of applications, including shape generation, shape interpolation, shape space embedding and shape exploration, outperforming state-of-the-art methods.Comment: CVPR 201

Dark Matter Subhalo Evaporation by Coulomb-like Interaction with Galactic Gas

Coulomb-like interactions typically has a cross section scales with velocity dependence as $\sigma=\sigma_0 v^{-4}$. The momentum transfer rate between a slightly charged dark matter and ionized particles increases significantly at low velocity, and it produces prominent evaporation effects on small-sized dark matter overdensities. We show that when subhalos encounter the hot gases near the Milky Way's disc, their survival can place stringent limits on Coulomb-like scattering strength. For $M<10^5 M_\odot$ subhalos to survive a kilo-parsec distance from the galactic center, with a dark matter mass in the sub-GeV range, the evaporation limit becomes one order of magnitude stronger than the limits from current cosmic microwave background and baryon acoustic oscillation data. We also interpret our bounds into the electron-recoil direct detection cross section, and show that the evaporation effect can lead to a stronger constraint on Coulomb-like interaction for sub-MeV dark matter in comparison with direct detection experiments.Comment: 7 pages, 4 figure