Learning local descriptors with adversarial enhancer from volumetric geometry patches

Local matching problems (e.g. key point matching, geometry registration) are significant but challenging tasks in computer vision field. In this paper, we propose to learn a robust local 3D descriptor from volumetric point patches to tackle the local matching tasks. Intuitively, given two inputs, it would be easy for a network to map the inputs to a space with similar characteristics (e.g. similar outputs for similar inputs, far different outputs for far different inputs), but the difficult case for a network would be to map the inputs into a space with opposite characteristics (e.g. far different outputs for very similar inputs but very similar outputs for far different inputs). Inspired by this intuition, in our proposed method, we design a siamese-network-based local descriptor generator to learn a local descriptor with small distances between match pairs and large distances between non-match pairs. Specifically, an adversarial enhancer is introduced to map the outputs of the local descriptor generator into an opposite space that match pairs have the maximum differences and non-match pairs have the minimum differences. The local descriptor generator and the adversarial enhancer are trained in an adversarial manner. By competing with the adversarial enhancer, the local descriptor generator learns to generate a much stronger descriptor for given volumetric point patches. The experiments conducted on real-world scan datasets, including 7-scenes and SUN3D, and the synthetic scan augmented ICL-NUIM dataset show that our method can achieve superior performance over other state-of-the-art approaches on both keypoint matching and geometry registration, such as fragment alignment and scene reconstruction.