1. Introduction
Semantic segmentation is the task of assigning a class label to each pixel in an image and is one of the fundamental problems in computer vision. Semantic segmentation has also been used to integrate higher-level scene understanding into other computer vision problems, e.g., dense 3D reconstruction [6, 13, 14, 23, 28, 31, 55, 56, 61], SLAM [7], [35], Structure-from-Motion [3], 3D model alignment [15], [16], [73], and location recognition [1], [42], [60].