Question for compute_iou

[Hongyeob Kim]

Firstly thanks for the greatest work.

If I got iou equation correctly, I need to get W and H for each predicted bounding boxes and target boxes and overlapping boxes respectively to calculate iou score. And here W, H is boxes[:, 2] - boxes[:, 0] and boxes[:, 3] - boxes[:, 1] respectively.

But compute_iou function below take W, H as boxes[:, 2] + boxes[:, 0] and boxes[:, 3] + boxes[:, 1] respectively.
Here is the question. Is there any specific reason for calculating iou scores like below or am I get wrong about iou score equation?

AdelaiDet/adet/utils/comm.py

Lines 81 to 94 in c0b2092

 target_aera = (target_left + target_right) * \ 
               (target_top + target_bottom) 
 pred_aera = (pred_left + pred_right) * \ 
             (pred_top + pred_bottom) 
  
 w_intersect = torch.min(pred_left, target_left) + \ 
               torch.min(pred_right, target_right) 
 h_intersect = torch.min(pred_bottom, target_bottom) + \ 
               torch.min(pred_top, target_top) 
  
 g_w_intersect = torch.max(pred_left, target_left) + \ 
                 torch.max(pred_right, target_right) 
 g_h_intersect = torch.max(pred_bottom, target_bottom) + \ 
                 torch.max(pred_top, target_top) 

[Hongyeob Kim]

I got it... for FCOS l∗, t∗, r*,b∗ are the distances from the location to the four sides of the bound-ing box.