def calculate_multiple_iou(box_a, box_b):
"""
Args:
box_a: numpy.ndarray(dtype=np.int, shape=(num_a, 4))
x0y0x1y1 convention.
box_b: numpy.ndarray(dtype=np.int, shape=(num_b, 4))
x0y0x1y1 convention.
Returns:
ious: numpy.ndarray(dtype=np.int, shape(num_a, num_b))
"""
num_a = box_a.shape[0]
num_b = box_b.shape[0]
check_box_convention(box_a, 'x0y0x1y1')
check_box_convention(box_b, 'x0y0x1y1')
# num_a x 4 -> num_a x num_b x 4
box_a = np.tile(box_a, num_b)
box_a = np.expand_dims(box_a, axis=1).reshape((num_a, num_b, -1))
# num_b x 4 -> num_b x num_a x 4
box_b = np.tile(box_b, num_a)
box_b = np.expand_dims(box_b, axis=1).reshape((num_b, num_a, -1))
# num_b x num_a x 4 -> num_a x num_b x 4
box_b = np.transpose(box_b, (1, 0, 2))
# num_a x num_b
min_x = np.maximum(box_a[:, :, 0], box_b[:, :, 0])
min_y = np.maximum(box_a[:, :, 1], box_b[:, :, 1])
max_x = np.minimum(box_a[:, :, 2], box_b[:, :, 2])
max_y = np.minimum(box_a[:, :, 3], box_b[:, :, 3])
# num_a x num_b
area_intersect = (np.maximum(0, max_x - min_x + 1) *
np.maximum(0, max_y - min_y + 1))
area_a = ((box_a[:, :, 2] - box_a[:, :, 0] + 1) *
(box_a[:, :, 3] - box_a[:, :, 1] + 1))
area_b = ((box_b[:, :, 2] - box_b[:, :, 0] + 1) *
(box_b[:, :, 3] - box_b[:, :, 1] + 1))
denominator = area_a + area_b - area_intersect
degenerate_indices = np.where(denominator <= 0)
denominator[degenerate_indices] = 1
ious = area_intersect / denominator
ious[degenerate_indices] = 0
return ious
def resize_bbox(box, image_size, resize_size):
"""
Args:
box: iterable (ints) of length 4 (x0, y0, x1, y1)
image_size: iterable (ints) of length 2 (width, height)
resize_size: iterable (ints) of length 2 (width, height)
Returns:
new_box: iterable (ints) of length 4 (x0, y0, x1, y1)
"""
check_box_convention(np.array(box), 'x0y0x1y1')
box_x0, box_y0, box_x1, box_y1 = map(float, box)
image_w, image_h = map(float, image_size)
new_image_w, new_image_h = map(float, resize_size)
newbox_x0 = box_x0 * new_image_w / image_w
newbox_y0 = box_y0 * new_image_h / image_h
newbox_x1 = box_x1 * new_image_w / image_w
newbox_y1 = box_y1 * new_image_h / image_h
return int(newbox_x0), int(newbox_y0), int(newbox_x1), int(newbox_y1)
