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import math
import torch
def diou_loss(
boxes1: torch.Tensor,
boxes2: torch.Tensor,
reduction: str = "none",
eps: float = 1e-7,
) -> torch.Tensor:
"""
Distance Intersection over Union Loss (Zhaohui Zheng et. al)
https://arxiv.org/abs/1911.08287
Args:
boxes1, boxes2 (Tensor): box locations in XYXY format, shape (N, 4) or (4,).
reduction: 'none' | 'mean' | 'sum'
'none': No reduction will be applied to the output.
'mean': The output will be averaged.
'sum': The output will be summed.
eps (float): small number to prevent division by zero
"""
x1, y1, x2, y2 = boxes1.unbind(dim=-1)
x1g, y1g, x2g, y2g = boxes2.unbind(dim=-1)
# TODO: use torch._assert_async() when pytorch 1.8 support is dropped
assert (x2 >= x1).all(), "bad box: x1 larger than x2"
assert (y2 >= y1).all(), "bad box: y1 larger than y2"
# Intersection keypoints
xkis1 = torch.max(x1, x1g)
ykis1 = torch.max(y1, y1g)
xkis2 = torch.min(x2, x2g)
ykis2 = torch.min(y2, y2g)
intsct = torch.zeros_like(x1)
mask = (ykis2 > ykis1) & (xkis2 > xkis1)
intsct[mask] = (xkis2[mask] - xkis1[mask]) * (ykis2[mask] - ykis1[mask])
union = (x2 - x1) * (y2 - y1) + (x2g - x1g) * (y2g - y1g) - intsct + eps
iou = intsct / union
# smallest enclosing box
xc1 = torch.min(x1, x1g)
yc1 = torch.min(y1, y1g)
xc2 = torch.max(x2, x2g)
yc2 = torch.max(y2, y2g)
diag_len = ((xc2 - xc1) ** 2) + ((yc2 - yc1) ** 2) + eps
# centers of boxes
x_p = (x2 + x1) / 2
y_p = (y2 + y1) / 2
x_g = (x1g + x2g) / 2
y_g = (y1g + y2g) / 2
distance = ((x_p - x_g) ** 2) + ((y_p - y_g) ** 2)
# Eqn. (7)
loss = 1 - iou + (distance / diag_len)
if reduction == "mean":
loss = loss.mean() if loss.numel() > 0 else 0.0 * loss.sum()
elif reduction == "sum":
loss = loss.sum()
return loss
def ciou_loss(
boxes1: torch.Tensor,
boxes2: torch.Tensor,
reduction: str = "none",
eps: float = 1e-7,
) -> torch.Tensor:
"""
Complete Intersection over Union Loss (Zhaohui Zheng et. al)
https://arxiv.org/abs/1911.08287
Args:
boxes1, boxes2 (Tensor): box locations in XYXY format, shape (N, 4) or (4,).
reduction: 'none' | 'mean' | 'sum'
'none': No reduction will be applied to the output.
'mean': The output will be averaged.
'sum': The output will be summed.
eps (float): small number to prevent division by zero
"""
x1, y1, x2, y2 = boxes1.unbind(dim=-1)
x1g, y1g, x2g, y2g = boxes2.unbind(dim=-1)
# TODO: use torch._assert_async() when pytorch 1.8 support is dropped
assert (x2 >= x1).all(), "bad box: x1 larger than x2"
assert (y2 >= y1).all(), "bad box: y1 larger than y2"
# Intersection keypoints
xkis1 = torch.max(x1, x1g)
ykis1 = torch.max(y1, y1g)
xkis2 = torch.min(x2, x2g)
ykis2 = torch.min(y2, y2g)
intsct = torch.zeros_like(x1)
mask = (ykis2 > ykis1) & (xkis2 > xkis1)
intsct[mask] = (xkis2[mask] - xkis1[mask]) * (ykis2[mask] - ykis1[mask])
union = (x2 - x1) * (y2 - y1) + (x2g - x1g) * (y2g - y1g) - intsct + eps
iou = intsct / union
# smallest enclosing box
xc1 = torch.min(x1, x1g)
yc1 = torch.min(y1, y1g)
xc2 = torch.max(x2, x2g)
yc2 = torch.max(y2, y2g)
diag_len = ((xc2 - xc1) ** 2) + ((yc2 - yc1) ** 2) + eps
# centers of boxes
x_p = (x2 + x1) / 2
y_p = (y2 + y1) / 2
x_g = (x1g + x2g) / 2
y_g = (y1g + y2g) / 2
distance = ((x_p - x_g) ** 2) + ((y_p - y_g) ** 2)
# width and height of boxes
w_pred = x2 - x1
h_pred = y2 - y1
w_gt = x2g - x1g
h_gt = y2g - y1g
v = (4 / (math.pi**2)) * torch.pow((torch.atan(w_gt / h_gt) - torch.atan(w_pred / h_pred)), 2)
with torch.no_grad():
alpha = v / (1 - iou + v + eps)
# Eqn. (10)
loss = 1 - iou + (distance / diag_len) + alpha * v
if reduction == "mean":
loss = loss.mean() if loss.numel() > 0 else 0.0 * loss.sum()
elif reduction == "sum":
loss = loss.sum()
return loss
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