Relationship between cam_root, transl, cam_trans and cam_scale in pose_output

[Tengoles]

Hello! wanted to get some clarification on what is the relationship between the pose_output parameters mentioned in the title. I know they are all related with the world coordinates, camera coordinates and root position of the body but not sure exactly how.

[Jeff-sjtu]

Hi @Tengoles, camera_root is the root position in the camera coordinates. But the SMPL model will add a default offset to the root joint after both forward kinematics and inverse kinematics. Therefore, we use the term transl which considers the default offset. cam_trans and cam_scale are used for training. Following HMR, cam_trans is related to tx and ty, and cam_scale is the scale term.