PointGMM: a Neural GMM Network for Point Clouds
This work addresses shape representation for 3D computer vision, offering a method for generative modeling and registration, but it appears incremental as it builds on existing GMM and neural network techniques.
The paper tackles the problem of representing 3D point clouds with shape priors by introducing PointGMM, a neural network that learns hierarchical Gaussian mixture models, resulting in a compact representation that enables shape generation and rigid registration.
Point clouds are a popular representation for 3D shapes. However, they encode a particular sampling without accounting for shape priors or non-local information. We advocate for the use of a hierarchical Gaussian mixture model (hGMM), which is a compact, adaptive and lightweight representation that probabilistically defines the underlying 3D surface. We present PointGMM, a neural network that learns to generate hGMMs which are characteristic of the shape class, and also coincide with the input point cloud. PointGMM is trained over a collection of shapes to learn a class-specific prior. The hierarchical representation has two main advantages: (i) coarse-to-fine learning, which avoids converging to poor local-minima; and (ii) (an unsupervised) consistent partitioning of the input shape. We show that as a generative model, PointGMM learns a meaningful latent space which enables generating consistent interpolations between existing shapes, as well as synthesizing novel shapes. We also present a novel framework for rigid registration using PointGMM, that learns to disentangle orientation from structure of an input shape.