Where in the code do you handle ego motion?

[Slonna]

Dear author
Wonderful work! Where in the code do you handle ego motion? I can't find it.
It seems that after moving the sampling points with velocity, it directly uses the lidar2img matrix to project points

[Haisong Liu]

Ego motion is integrated into lidar2img during data loading:

SparseBEV/loaders/pipelines/loading.py

Lines 9 to 32 in 4d028e9

 def compose_lidar2img(ego2global_translation_curr, 
                       ego2global_rotation_curr, 
                       lidar2ego_translation_curr, 
                       lidar2ego_rotation_curr, 
                       sensor2global_translation_past, 
                       sensor2global_rotation_past, 
                       cam_intrinsic_past): 
      
     R = sensor2global_rotation_past @ (inv(ego2global_rotation_curr).T @ inv(lidar2ego_rotation_curr).T) 
     T = sensor2global_translation_past @ (inv(ego2global_rotation_curr).T @ inv(lidar2ego_rotation_curr).T) 
     T -= ego2global_translation_curr @ (inv(ego2global_rotation_curr).T @ inv(lidar2ego_rotation_curr).T) + lidar2ego_translation_curr @ inv(lidar2ego_rotation_curr).T 
  
     lidar2cam_r = inv(R.T) 
     lidar2cam_t = T @ lidar2cam_r.T 
  
     lidar2cam_rt = np.eye(4) 
     lidar2cam_rt[:3, :3] = lidar2cam_r.T 
     lidar2cam_rt[3, :3] = -lidar2cam_t 
  
     viewpad = np.eye(4) 
     viewpad[:cam_intrinsic_past.shape[0], :cam_intrinsic_past.shape[1]] = cam_intrinsic_past 
     lidar2img = (viewpad @ lidar2cam_rt.T).astype(np.float32) 
  
     return lidar2img 

[Slonna]

Thanks for your quick rely! I got it.