Read about the 'bin 'file

[xu19971109]

1. I didn't known why there is no directory like 'nuscenes_gt_database/pts_dir/xxx.bin', in my directory structure, the path need to change to 'nuscenes_gt_database/xxx.bin'.And I need to change the data_root=None in UnifiedDataBaseSampler config to data_root=data_root. The len of bin file which I read is more than 6w. Is this normal? (I followed mmdet3d to prepare for nuscenes.)

2. About read bin file, I find there is an error in np.frombuffer(pts_bytes, dtype=np.float32): buffer size must be a multiple of element size. The reason is that the bytes need to change b'\x00' to \x00, actually is np.frombuffer(pts_bytes[2:-1], dtype=np.float32 Is there is a bug in mmcv?

[junjie18]

@xu19971109

Use the code in CMT to re-generate. Since official mmdetection3d only provide point cloud copy paste.