Coordinate_Sys.md

Three camera coord sys in eval code

Waymo (OpenLane) camera coord sys. x-front, y-left, z-up

normal (aka. standard) camera coord sys widely used. x-right, y-down, z-front

LaneNet (3D-LaneNet) camera coord sys. x-right, y-front, z-up

The transformation matrices in the code

• cam_representation: Waymo to normal https://github.com/OpenPerceptionX/OpenLane/blob/1e8e61ccb456232955cf999b8db2aa4023945d25/eval/LANE_evaluation/lane3d/eval_3D_lane.py#L333-L338
• R_gc: normal to LaneNet https://github.com/OpenPerceptionX/OpenLane/blob/1e8e61ccb456232955cf999b8db2aa4023945d25/eval/LANE_evaluation/lane3d/eval_3D_lane.py#L305-L307
• R_vg: LaneNet to Waymo https://github.com/OpenPerceptionX/OpenLane/blob/1e8e61ccb456232955cf999b8db2aa4023945d25/eval/LANE_evaluation/lane3d/eval_3D_lane.py#L302-L304
• original cam_extrinsics in JSON: Waymo camera to Waymo vehicle
• inv(R_vg): Waymo to LaneNet

Note that the 3D lane GT are annotated in the Waymo camera coord sys. With matrices above, the final cam_extrinsics can transform GT to road coord (which is right-down of the camera and actually has the same z height with Waymo vehicle coord rather than on the road, with setting x/y=0 in the last line of code). https://github.com/OpenPerceptionX/OpenLane/blob/1e8e61ccb456232955cf999b8db2aa4023945d25/eval/LANE_evaluation/lane3d/eval_3D_lane.py#L308-L314

In conclusion, there are some redundancies in the process and one could try to use only R_vg and original cam_extrinsics to see if they could get the same results.

Pose Info in OpenLaneV1.2

Waymo (OpenLane) vehicle coord sys: vehicle to global

point_global = pose_matrix @ point_vehicle