MP-Mono: Monocular 3D Detection Using Multiple Priors for Autonomous Driving

Monocular 3D object detection is an important and challenging task in autonomous driving. Due to the ill-posed nature of 3D detection, recent studies use prior knowledge on object categories to estimate 3D parameters. However, for each object category in real driving scenes, there exist a couple of sub-categories with different shapes (i.e. length, width, and height). For example, vehicle generally contains the sub-categories of car, van, and truck. Obviously, single prior knowledge cannot cover such diverse sub-categories. In this paper, we propose MP-Mono that exploits multiple priors to improve object detection. Specifically, a data-heuristic strategy is presented to generate multiple 3D proposals, in which we leverage the unsupervised algorithm to cluster potential sub-categories from realistic datasets, and a height-guided inference policy is used to determine the initial distances of proposals, reducing the difficulty of network learning. Additionally, we propose a local-ground embedding method that learns local depth information to enhance monocular 3D detection. The experimental results on the KITTI dataset demonstrate that our MP-Mono achieves competitive performances compared to other monocular methods, verifying the effectiveness of multi-prior integration and local-ground embedding.