目标检测回归损失函数简介：SmoothL1/IoU/GIoU/DIoU/CIoU Loss
https://mp.weixin.qq.com/s?__biz=MzI5MDUyMDIxNA==&mid=2247493294&idx=1&sn=d64822f1c2ca25901f7b707d78028364&chksm=ec1c0b57db6b82414c9177a13da5c1cceda8963785e22cb777b43892608c9ce71afc90c8d0c1&token=1513639846&lang=zh_CN#rd

代码

https://sourcegraph.com/github.com/Zzh-tju/DIoU-darknet/-/blob/src/box.c#L243

  1. def bbox_iou(box1, box2, x1y1x2y2=True, GIoU=False, DIoU=False, CIoU=False):
  2.     # Get the coordinates of bounding boxes
  3.     if x1y1x2y2:  # x1, y1, x2, y2 = box1
  4.         b1_x1, b1_y1, b1_x2, b1_y2 = box1[0], box1[1], box1[2], box1[3]
  5.         b2_x1, b2_y1, b2_x2, b2_y2 = box2[0], box2[1], box2[2], box2[3]
  6.     else:  # x, y, w, h = box1
  7.         b1_x1, b1_x2 = box1[0] - box1[2] / 2, box1[0] + box1[2] / 2
  8.         b1_y1, b1_y2 = box1[1] - box1[3] / 2, box1[1] + box1[3] / 2
  9.         b2_x1, b2_x2 = box2[0] - box2[2] / 2, box2[0] + box2[2] / 2
  10.         b2_y1, b2_y2 = box2[1] - box2[3] / 2, box2[1] + box2[3] / 2
  12.     # Intersection area
  13.     inter = (min(b1_x2, b2_x2) - max(b1_x1, b2_x1)).clamp(0) * \
  14.             (min(b1_y2, b2_y2) - max(b1_y1, b2_y1)).clamp(0)
  16.     # Union Area
  17.     w1, h1 = b1_x2 - b1_x1, b1_y2 - b1_y1
  18.     w2, h2 = b2_x2 - b2_x1, b2_y2 - b2_y1
  19.     union = (w1 * h1 + 1e-16) + w2 * h2 - inter
  21.     iou = inter / union  # iou
  22.     if GIoU or DIoU or CIoU:
  23.         cw = max(b1_x2, b2_x2) - min(b1_x1, b2_x1)  # convex (smallest enclosing box) width
  24.         ch = max(b1_y2, b2_y2) - min(b1_y1, b2_y1)  # convex height
  25.         if GIoU:  # Generalized IoU https://arxiv.org/pdf/1902.09630.pdf
  26.             c_area = cw * ch + 1e-16  # convex area
  27.             return iou - (c_area - union) / c_area  # GIoU
  28.         if DIoU or CIoU:  # Distance or Complete IoU https://arxiv.org/abs/1911.08287v1
  29.             # convex diagonal squared
  30.             c2 = cw ** 2 + ch ** 2 + 1e-16
  31.             # centerpoint distance squared
  32.             rho2 = ((b2_x1 + b2_x2) - (b1_x1 + b1_x2)) ** 2 / 4 + ((b2_y1 + b2_y2) - (b1_y1 + b1_y2)) ** 2 / 4
  33.             if DIoU:
  34.                 return iou - rho2 / c2  # DIoU
  35.             elif CIoU:  # https://github.com/Zzh-tju/DIoU-SSD-pytorch/blob/master/utils/box/box_utils.py#L47
  36.                 v = (4 / math.pi ** 2) * pow(atan(w2 / h2) - atan(w1 / h1), 2)
  37.                 with no_grad():
  38.                     alpha = v / (1 - iou + v)
  39.                 return iou - (rho2 / c2 + v * alpha)  # CIoU
  41.     return iou