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# Copyright (c) OpenMMLab. All rights reserved. | |
import torch | |
def images_to_levels(target, num_levels): | |
"""Convert targets by image to targets by feature level. | |
[target_img0, target_img1] -> [target_level0, target_level1, ...] | |
""" | |
target = torch.stack(target, 0) | |
level_targets = [] | |
start = 0 | |
for n in num_levels: | |
end = start + n | |
# level_targets.append(target[:, start:end].squeeze(0)) | |
level_targets.append(target[:, start:end]) | |
start = end | |
return level_targets | |
def anchor_inside_flags(flat_anchors, | |
valid_flags, | |
img_shape, | |
allowed_border=0): | |
"""Check whether the anchors are inside the border. | |
Args: | |
flat_anchors (torch.Tensor): Flatten anchors, shape (n, 4). | |
valid_flags (torch.Tensor): An existing valid flags of anchors. | |
img_shape (tuple(int)): Shape of current image. | |
allowed_border (int, optional): The border to allow the valid anchor. | |
Defaults to 0. | |
Returns: | |
torch.Tensor: Flags indicating whether the anchors are inside a \ | |
valid range. | |
""" | |
img_h, img_w = img_shape[:2] | |
if allowed_border >= 0: | |
inside_flags = valid_flags & \ | |
(flat_anchors[:, 0] >= -allowed_border) & \ | |
(flat_anchors[:, 1] >= -allowed_border) & \ | |
(flat_anchors[:, 2] < img_w + allowed_border) & \ | |
(flat_anchors[:, 3] < img_h + allowed_border) | |
else: | |
inside_flags = valid_flags | |
return inside_flags | |
def calc_region(bbox, ratio, featmap_size=None): | |
"""Calculate a proportional bbox region. | |
The bbox center are fixed and the new h' and w' is h * ratio and w * ratio. | |
Args: | |
bbox (Tensor): Bboxes to calculate regions, shape (n, 4). | |
ratio (float): Ratio of the output region. | |
featmap_size (tuple): Feature map size used for clipping the boundary. | |
Returns: | |
tuple: x1, y1, x2, y2 | |
""" | |
x1 = torch.round((1 - ratio) * bbox[0] + ratio * bbox[2]).long() | |
y1 = torch.round((1 - ratio) * bbox[1] + ratio * bbox[3]).long() | |
x2 = torch.round(ratio * bbox[0] + (1 - ratio) * bbox[2]).long() | |
y2 = torch.round(ratio * bbox[1] + (1 - ratio) * bbox[3]).long() | |
if featmap_size is not None: | |
x1 = x1.clamp(min=0, max=featmap_size[1]) | |
y1 = y1.clamp(min=0, max=featmap_size[0]) | |
x2 = x2.clamp(min=0, max=featmap_size[1]) | |
y2 = y2.clamp(min=0, max=featmap_size[0]) | |
return (x1, y1, x2, y2) | |