  We present RangeRCNN, a novel and effective 3D object detection framework
based on the range image representation. Most existing methods are voxel-based
or point-based. Though several optimizations have been introduced to ease the
sparsity issue and speed up the running time, the two representations are still
computationally inefficient. Compared to them, the range image representation
is dense and compact which can exploit powerful 2D convolution. Even so, the
range image is not preferred in 3D object detection due to scale variation and
occlusion. In this paper, we utilize the dilated residual block (DRB) to better
adapt different object scales and obtain a more flexible receptive field.
Considering scale variation and occlusion, we propose the RV-PV-BEV (range
view-point view-bird's eye view) module to transfer features from RV to BEV.
The anchor is defined in BEV which avoids scale variation and occlusion.
Neither RV nor BEV can provide enough information for height estimation;
therefore, we propose a two-stage RCNN for better 3D detection performance. The
aforementioned point view not only serves as a bridge from RV to BEV but also
provides pointwise features for RCNN. Experiments show that RangeRCNN achieves
state-of-the-art performance on the KITTI dataset and the Waymo Open dataset,
and provides more possibilities for real-time 3D object detection. We further
introduce and discuss the data augmentation strategy for the range image based
method, which will be very valuable for future research on range image.
