  Visual data in autonomous driving perception, such as camera image and LiDAR
point cloud, can be interpreted as a mixture of two aspects: semantic feature
and geometric structure. Semantics come from the appearance and context of
objects to the sensor, while geometric structure is the actual 3D shape of
point clouds. Most detectors on LiDAR point clouds focus only on analyzing the
geometric structure of objects in real 3D space. Unlike previous works, we
propose to learn both semantic feature and geometric structure via a unified
multi-view framework. Our method exploits the nature of LiDAR scans -- 2D range
images, and applies well-studied 2D convolutions to extract semantic features.
By fusing semantic and geometric features, our method outperforms
state-of-the-art approaches in all categories by a large margin. The
methodology of combining semantic and geometric features provides a unique
perspective of looking at the problems in real-world 3D point cloud detection.
