Learning to Reconstruct 3D Structures for Occupancy Mapping


Authors: Vitor Guizilini, Fabio Ramos

Real world scenarios contain many structural patterns that, if appropriately extracted and modeled, can be used to reduce problems associated with sensor failure and occlusions, while improving planning methods in tasks such as navigation and grasping. This paper devises a novel unsupervised procedure that is able to learn 3D structures from unorganized point clouds as occupancy maps. Our framework enables the learning of unique and arbitrarily complex features using a Bayesian Convolutional Variational Auto-Encoder, that compresses local information into a latent low-dimensional representation and then decodes it back in order to reconstruct the original scene. This reconstructive model is trained on features obtained automatically from a wide variety of scenarios, to improve its generalization and interpolative powers. We show that the proposed framework is able to recover partially missing structures and reason over occlusion with high accuracy, while maintaining a detailed reconstruction of observed areas. To seamlessly combine this localized feature information into a single global structure, we employ a Hilbert Map, recently proposed as a robust and efficient occupancy mapping technique. Experimental tests are conducted in large-scale 2D and 3D datasets, and a study on the impact of various accuracy/speed trade-offs is provided to test the limits of the proposed framework.