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# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved | |
""" | |
Utilities for bounding box manipulation and GIoU. | |
""" | |
import torch | |
from torchvision.ops.boxes import box_area | |
import pdb | |
def box_cxcywh_to_xyxy(x): | |
x_c, y_c, w, h = x.unbind(-1) | |
b = [(x_c - 0.5 * w), (y_c - 0.5 * h), | |
(x_c + 0.5 * w), (y_c + 0.5 * h)] | |
return torch.stack(b, dim=-1) | |
def box_xyxy_to_cxcywh(x): | |
x0, y0, x1, y1 = x.unbind(-1) | |
b = [(x0 + x1) / 2, (y0 + y1) / 2, | |
(x1 - x0), (y1 - y0)] | |
return torch.stack(b, dim=-1) | |
def rescale_bboxes(out_bbox, size): | |
img_h, img_w = size | |
b = out_bbox | |
#b = box_cxcywh_to_xyxy(out_bbox) | |
b = b * torch.tensor([img_w, img_h, img_w, img_h], dtype=torch.float32, device=b.device) | |
return b | |
# modified from torchvision to also return the union | |
def box_iou(boxes1, boxes2): | |
area1 = box_area(boxes1) | |
area2 = box_area(boxes2) | |
lt = torch.max(boxes1[:, None, :2], boxes2[:, :2]) # [N,M,2] | |
rb = torch.min(boxes1[:, None, 2:], boxes2[:, 2:]) # [N,M,2] | |
wh = (rb - lt).clamp(min=0) # [N,M,2] | |
inter = wh[:, :, 0] * wh[:, :, 1] # [N,M] | |
union = area1[:, None] + area2 - inter | |
iou = inter / union | |
return iou, union | |
def generalized_box_iou(boxes1, boxes2): | |
""" | |
Generalized IoU from https://giou.stanford.edu/ | |
The boxes should be in [x0, y0, x1, y1] format | |
Returns a [N, M] pairwise matrix, where N = len(boxes1) | |
and M = len(boxes2) | |
""" | |
# degenerate boxes gives inf / nan results | |
# so do an early check | |
assert (boxes1[:, 2:] >= boxes1[:, :2]).all() | |
assert (boxes2[:, 2:] >= boxes2[:, :2]).all() | |
iou, union = box_iou(boxes1, boxes2) | |
lt = torch.min(boxes1[:, None, :2], boxes2[:, :2]) | |
rb = torch.max(boxes1[:, None, 2:], boxes2[:, 2:]) | |
wh = (rb - lt).clamp(min=0) # [N,M,2] | |
area = wh[:, :, 0] * wh[:, :, 1] | |
return iou - (area - union) / area | |
def masks_to_boxes(masks): | |
"""Compute the bounding boxes around the provided masks | |
The masks should be in format [N, H, W] where N is the number of masks, (H, W) are the spatial dimensions. | |
Returns a [N, 4] tensors, with the boxes in xyxy format | |
""" | |
if masks.numel() == 0: | |
return torch.zeros((0, 4), device=masks.device) | |
h, w = masks.shape[-2:] | |
y = torch.arange(0, h, dtype=torch.float) | |
x = torch.arange(0, w, dtype=torch.float) | |
y, x = torch.meshgrid(y, x) | |
x_mask = (masks * x.unsqueeze(0)) | |
x_max = x_mask.flatten(1).max(-1)[0] | |
x_min = x_mask.masked_fill(~(masks.bool()), 1e8).flatten(1).min(-1)[0] | |
y_mask = (masks * y.unsqueeze(0)) | |
y_max = y_mask.flatten(1).max(-1)[0] | |
y_min = y_mask.masked_fill(~(masks.bool()), 1e8).flatten(1).min(-1)[0] | |
return torch.stack([x_min, y_min, x_max, y_max], 1) |