Neural Implicit Embedding for Point Cloud Analysis

We present a novel representation for point clouds that encapsulates the local characteristics of the underlying structure. The key idea is to embed an implicit representation of the point cloud, namely the distance field, into neural networks. One neural network is used to embed a portion of the distance field around a point. The resulting network weights are concatenated to be used as a representation of the corresponding point cloud instance. To enable comparison among the weights, Extreme Learning Machine (ELM) is employed as the embedding network. Invariance to scale and coordinate change can be achieved by introducing a scale commutative activation layer to the ELM, and aligning the distance field into a canonical pose. Experimental results using our representation demonstrate that our proposal is capable of similar or better classification and segmentation performance compared to the state-of-the-art point-based methods, while requiring less time for training.