[Fix] Converting point with specified rt_matrix (#556)

* [Fix] Converting point with specify rt_matrix

* boundary condition

* more readability and comprehensibility

mmdet3d/core/bbox/structures/coord_3d_mode.py

@@ -221,10 +221,15 @@ def convert_point(point, src, dst, rt_mat=None):
  # TODO: LIDAR
  # only implemented provided Rt matrix in cam-depth conversion
  if src == Coord3DMode.LIDAR and dst == Coord3DMode.CAM:
- rt_mat = arr.new_tensor([[0, -1, 0], [0, 0, -1], [1, 0, 0]])
+ if rt_mat is None:
+ rt_mat = arr.new_tensor([[0, -1, 0], [0, 0, -1], [1, 0, 0]])
  elif src == Coord3DMode.CAM and dst == Coord3DMode.LIDAR:
- rt_mat = arr.new_tensor([[0, 0, 1], [-1, 0, 0], [0, -1, 0]])
+ if rt_mat is None:
+ rt_mat = arr.new_tensor([[0, 0, 1], [-1, 0, 0], [0, -1, 0]])
  elif src == Coord3DMode.DEPTH and dst == Coord3DMode.CAM:
+ # LIDAR-CAM conversion is different from DEPTH-CAM conversion
+ # because SUNRGB-D camera calibration files are different from
+ # that of KITTI, and currently we keep this hack
  if rt_mat is None:
  rt_mat = arr.new_tensor([[1, 0, 0], [0, 0, -1], [0, 1, 0]])
  else:
@@ -238,9 +243,11 @@ def convert_point(point, src, dst, rt_mat=None):
  rt_mat = rt_mat @ rt_mat.new_tensor([[1, 0, 0], [0, 0, 1],
  [0, -1, 0]])
  elif src == Coord3DMode.LIDAR and dst == Coord3DMode.DEPTH:
- rt_mat = arr.new_tensor([[0, -1, 0], [1, 0, 0], [0, 0, 1]])
+ if rt_mat is None:
+ rt_mat = arr.new_tensor([[0, -1, 0], [1, 0, 0], [0, 0, 1]])
  elif src == Coord3DMode.DEPTH and dst == Coord3DMode.LIDAR:
- rt_mat = arr.new_tensor([[0, 1, 0], [-1, 0, 0], [0, 0, 1]])
+ if rt_mat is None:
+ rt_mat = arr.new_tensor([[0, 1, 0], [-1, 0, 0], [0, 0, 1]])
  else:
  raise NotImplementedError(
  f'Conversion from Coord3DMode {src} to {dst} '