def concatenate(box_mask_lists, fields=None):
"""Concatenate list of box_mask_lists.
This op concatenates a list of input box_mask_lists into a larger
box_mask_list. It also
handles concatenation of box_mask_list fields as long as the field tensor
shapes are equal except for the first dimension.
Args:
box_mask_lists: list of np_box_mask_list.BoxMaskList objects
fields: optional list of fields to also concatenate. By default, all
fields from the first BoxMaskList in the list are included in the
concatenation.
Returns:
a box_mask_list with number of boxes equal to
sum([box_mask_list.num_boxes() for box_mask_list in box_mask_list])
Raises:
ValueError: if box_mask_lists is invalid (i.e., is not a list, is empty, or
contains non box_mask_list objects), or if requested fields are not
contained in all box_mask_lists
"""
if fields is not None:
if 'masks' not in fields:
fields.append('masks')
return box_list_to_box_mask_list(
np_box_list_ops.concatenate(boxlists=box_mask_lists, fields=fields))
def test_concatenate(self):
boxlist1 = np_box_list.BoxList(
np.array([[0.25, 0.25, 0.75, 0.75], [0.0, 0.0, 0.5, 0.75]],
dtype=np.float32))
boxlist2 = np_box_list.BoxList(
np.array([[0.5, 0.25, 1.0, 1.0], [0.0, 0.0, 1.0, 1.0]],
dtype=np.float32))
boxlists = [boxlist1, boxlist2]
boxlist_concatenated = np_box_list_ops.concatenate(boxlists)
boxlist_concatenated_expected = np_box_list.BoxList(
np.array([[0.25, 0.25, 0.75, 0.75], [0.0, 0.0, 0.5, 0.75],
[0.5, 0.25, 1.0, 1.0], [0.0, 0.0, 1.0, 1.0]],
dtype=np.float32))
self.assertAllClose(boxlist_concatenated_expected.get(),
boxlist_concatenated.get())
def multi_class_non_max_suppression(box_mask_list, score_thresh, iou_thresh,
max_output_size):
"""Multi-class version of non maximum suppression.
This op greedily selects a subset of detection bounding boxes, pruning
away boxes that have high IOU (intersection over union) overlap (> thresh)
with already selected boxes. It operates independently for each class for
which scores are provided (via the scores field of the input box_list),
pruning boxes with score less than a provided threshold prior to
applying NMS.
Args:
box_mask_list: np_box_mask_list.BoxMaskList holding N boxes. Must contain a
'scores' field representing detection scores. This scores field is a
tensor that can be 1 dimensional (in the case of a single class) or
2-dimensional, in which case we assume that it takes the
shape [num_boxes, num_classes]. We further assume that this rank is known
statically and that scores.shape[1] is also known (i.e., the number of
classes is fixed and known at graph construction time).
score_thresh: scalar threshold for score (low scoring boxes are removed).
iou_thresh: scalar threshold for IOU (boxes that that high IOU overlap
with previously selected boxes are removed).
max_output_size: maximum number of retained boxes per class.
Returns:
a box_mask_list holding M boxes with a rank-1 scores field representing
corresponding scores for each box with scores sorted in decreasing order
and a rank-1 classes field representing a class label for each box.
Raises:
ValueError: if iou_thresh is not in [0, 1] or if input box_mask_list does
not have a valid scores field.
"""
if not 0 <= iou_thresh <= 1.0:
raise ValueError('thresh must be between 0 and 1')
if not isinstance(box_mask_list, np_box_mask_list.BoxMaskList):
raise ValueError('box_mask_list must be a box_mask_list')
if not box_mask_list.has_field('scores'):
raise ValueError('input box_mask_list must have \'scores\' field')
scores = box_mask_list.get_field('scores')
if len(scores.shape) == 1:
scores = np.reshape(scores, [-1, 1])
elif len(scores.shape) == 2:
if scores.shape[1] is None:
raise ValueError(
'scores field must have statically defined second '
'dimension')
else:
raise ValueError('scores field must be of rank 1 or 2')
num_boxes = box_mask_list.num_boxes()
num_scores = scores.shape[0]
num_classes = scores.shape[1]
if num_boxes != num_scores:
raise ValueError('Incorrect scores field length: actual vs expected.')
selected_boxes_list = []
for class_idx in range(num_classes):
box_mask_list_and_class_scores = np_box_mask_list.BoxMaskList(
box_data=box_mask_list.get(), mask_data=box_mask_list.get_masks())
class_scores = np.reshape(scores[0:num_scores, class_idx], [-1])
box_mask_list_and_class_scores.add_field('scores', class_scores)
box_mask_list_filt = filter_scores_greater_than(
box_mask_list_and_class_scores, score_thresh)
nms_result = non_max_suppression(box_mask_list_filt,
max_output_size=max_output_size,
iou_threshold=iou_thresh,
score_threshold=score_thresh)
nms_result.add_field(
'classes',
np.zeros_like(nms_result.get_field('scores')) + class_idx)
selected_boxes_list.append(nms_result)
selected_boxes = np_box_list_ops.concatenate(selected_boxes_list)
sorted_boxes = np_box_list_ops.sort_by_field(selected_boxes, 'scores')
return box_list_to_box_mask_list(boxlist=sorted_boxes)