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import numpy as np |
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def bbox_overlaps(bboxes1, |
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bboxes2, |
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mode='iou', |
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eps=1e-6, |
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use_legacy_coordinate=False): |
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"""Calculate the ious between each bbox of bboxes1 and bboxes2. |
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Args: |
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bboxes1 (ndarray): Shape (n, 4) |
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bboxes2 (ndarray): Shape (k, 4) |
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mode (str): IOU (intersection over union) or IOF (intersection |
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over foreground) |
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use_legacy_coordinate (bool): Whether to use coordinate system in |
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mmdet v1.x. which means width, height should be |
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calculated as 'x2 - x1 + 1` and 'y2 - y1 + 1' respectively. |
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Note when function is used in `VOCDataset`, it should be |
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True to align with the official implementation |
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`http://host.robots.ox.ac.uk/pascal/VOC/voc2012/VOCdevkit_18-May-2011.tar` |
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Default: False. |
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Returns: |
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ious (ndarray): Shape (n, k) |
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""" |
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assert mode in ['iou', 'iof'] |
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if not use_legacy_coordinate: |
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extra_length = 0. |
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else: |
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extra_length = 1. |
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bboxes1 = bboxes1.astype(np.float32) |
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bboxes2 = bboxes2.astype(np.float32) |
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rows = bboxes1.shape[0] |
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cols = bboxes2.shape[0] |
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ious = np.zeros((rows, cols), dtype=np.float32) |
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if rows * cols == 0: |
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return ious |
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exchange = False |
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if bboxes1.shape[0] > bboxes2.shape[0]: |
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bboxes1, bboxes2 = bboxes2, bboxes1 |
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ious = np.zeros((cols, rows), dtype=np.float32) |
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exchange = True |
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area1 = (bboxes1[:, 2] - bboxes1[:, 0] + extra_length) * ( |
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bboxes1[:, 3] - bboxes1[:, 1] + extra_length) |
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area2 = (bboxes2[:, 2] - bboxes2[:, 0] + extra_length) * ( |
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bboxes2[:, 3] - bboxes2[:, 1] + extra_length) |
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for i in range(bboxes1.shape[0]): |
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x_start = np.maximum(bboxes1[i, 0], bboxes2[:, 0]) |
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y_start = np.maximum(bboxes1[i, 1], bboxes2[:, 1]) |
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x_end = np.minimum(bboxes1[i, 2], bboxes2[:, 2]) |
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y_end = np.minimum(bboxes1[i, 3], bboxes2[:, 3]) |
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overlap = np.maximum(x_end - x_start + extra_length, 0) * np.maximum( |
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y_end - y_start + extra_length, 0) |
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if mode == 'iou': |
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union = area1[i] + area2 - overlap |
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else: |
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union = area1[i] if not exchange else area2 |
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union = np.maximum(union, eps) |
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ious[i, :] = overlap / union |
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if exchange: |
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ious = ious.T |
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return ious |
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