def _compute_targets(ex_rois, gt_rois):
"""Compute bounding-box regression targets for an image."""
assert ex_rois.shape[0] == gt_rois.shape[0]
assert ex_rois.shape[1] == 4
assert gt_rois.shape[1] == 5
return bbox_transform(ex_rois, gt_rois[:, :4]).astype(np.float32, copy=False)
def assign_anchor(feat_shape,
gt_boxes,
im_info,
cfg,
feat_stride=16,
scales=(8, 16, 32),
ratios=(0.5, 1, 2),
allowed_border=0):
"""
assign ground truth boxes to anchor positions
:param feat_shape: infer output shape
:param gt_boxes: assign ground truth
:param im_info: filter out anchors overlapped with edges
:param feat_stride: anchor position step
:param scales: used to generate anchors, affects num_anchors (per location)
:param ratios: aspect ratios of generated anchors
:param allowed_border: filter out anchors with edge overlap > allowed_border
:return: dict of label
'label': of shape (batch_size, 1) <- (batch_size, num_anchors, feat_height, feat_width)
'bbox_target': of shape (batch_size, num_anchors * 4, feat_height, feat_width)
'bbox_inside_weight': *todo* mark the assigned anchors
'bbox_outside_weight': used to normalize the bbox_loss, all weights sums to RPN_POSITIVE_WEIGHT
"""
def _unmap(data, count, inds, fill=0):
"""" unmap a subset inds of data into original data of size count """
if len(data.shape) == 1:
ret = np.empty((count, ), dtype=np.float32)
ret.fill(fill)
ret[inds] = data
else:
ret = np.empty((count, ) + data.shape[1:], dtype=np.float32)
ret.fill(fill)
ret[inds, :] = data
return ret
DEBUG = False
im_info = im_info[0]
scales = np.array(scales, dtype=np.float32)
base_anchors = generate_anchors(base_size=feat_stride,
ratios=list(ratios),
scales=scales)
num_anchors = base_anchors.shape[0]
feat_height, feat_width = feat_shape[-2:]
if DEBUG:
print 'anchors:'
print base_anchors
print 'anchor shapes:'
print np.hstack((base_anchors[:, 2::4] - base_anchors[:, 0::4],
base_anchors[:, 3::4] - base_anchors[:, 1::4]))
print 'im_info', im_info
print 'height', feat_height, 'width', feat_width
print 'gt_boxes shape', gt_boxes.shape
print 'gt_boxes', gt_boxes
# 1. generate proposals from bbox deltas and shifted anchors
shift_x = np.arange(0, feat_width) * feat_stride
shift_y = np.arange(0, feat_height) * feat_stride
shift_x, shift_y = np.meshgrid(shift_x, shift_y)
shifts = np.vstack((shift_x.ravel(), shift_y.ravel(), shift_x.ravel(),
shift_y.ravel())).transpose()
# add A anchors (1, A, 4) to
# cell K shifts (K, 1, 4) to get
# shift anchors (K, A, 4)
# reshape to (K*A, 4) shifted anchors
A = num_anchors
K = shifts.shape[0]
all_anchors = base_anchors.reshape((1, A, 4)) + shifts.reshape(
(1, K, 4)).transpose((1, 0, 2))
all_anchors = all_anchors.reshape((K * A, 4))
total_anchors = int(K * A)
# only keep anchors inside the image
inds_inside = np.where((all_anchors[:, 0] >= -allowed_border)
& (all_anchors[:, 1] >= -allowed_border)
& (all_anchors[:, 2] < im_info[1] + allowed_border)
& (all_anchors[:,
3] < im_info[0] + allowed_border))[0]
if DEBUG:
print 'total_anchors', total_anchors
print 'inds_inside', len(inds_inside)
# keep only inside anchors
anchors = all_anchors[inds_inside, :]
if DEBUG:
print 'anchors shape', anchors.shape
# label: 1 is positive, 0 is negative, -1 is dont care
labels = np.empty((len(inds_inside), ), dtype=np.float32)
labels.fill(-1)
if gt_boxes.size > 0:
# overlap between the anchors and the gt boxes
# overlaps (ex, gt)
overlaps = bbox_overlaps(anchors.astype(np.float),
gt_boxes.astype(np.float))
argmax_overlaps = overlaps.argmax(axis=1)
max_overlaps = overlaps[np.arange(len(inds_inside)), argmax_overlaps]
gt_argmax_overlaps = overlaps.argmax(axis=0)
gt_max_overlaps = overlaps[gt_argmax_overlaps,
np.arange(overlaps.shape[1])]
gt_argmax_overlaps = np.where(overlaps == gt_max_overlaps)[0]
if not cfg.TRAIN.RPN_CLOBBER_POSITIVES:
# assign bg labels first so that positive labels can clobber them
labels[max_overlaps < cfg.TRAIN.RPN_NEGATIVE_OVERLAP] = 0
# fg label: for each gt, anchor with highest overlap
labels[gt_argmax_overlaps] = 1
# fg label: above threshold IoU
labels[max_overlaps >= cfg.TRAIN.RPN_POSITIVE_OVERLAP] = 1
if cfg.TRAIN.RPN_CLOBBER_POSITIVES:
# assign bg labels last so that negative labels can clobber positives
labels[max_overlaps < cfg.TRAIN.RPN_NEGATIVE_OVERLAP] = 0
else:
labels[:] = 0
# subsample positive labels if we have too many
num_fg = int(cfg.TRAIN.RPN_FG_FRACTION * cfg.TRAIN.RPN_BATCH_SIZE)
fg_inds = np.where(labels == 1)[0]
if len(fg_inds) > num_fg:
disable_inds = npr.choice(fg_inds,
size=(len(fg_inds) - num_fg),
replace=False)
if DEBUG:
disable_inds = fg_inds[:(len(fg_inds) - num_fg)]
labels[disable_inds] = -1
# subsample negative labels if we have too many
num_bg = cfg.TRAIN.RPN_BATCH_SIZE - np.sum(labels == 1)
bg_inds = np.where(labels == 0)[0]
if len(bg_inds) > num_bg:
disable_inds = npr.choice(bg_inds,
size=(len(bg_inds) - num_bg),
replace=False)
if DEBUG:
disable_inds = bg_inds[:(len(bg_inds) - num_bg)]
labels[disable_inds] = -1
bbox_targets = np.zeros((len(inds_inside), 4), dtype=np.float32)
if gt_boxes.size > 0:
bbox_targets[:] = bbox_transform(anchors,
gt_boxes[argmax_overlaps, :4])
bbox_weights = np.zeros((len(inds_inside), 4), dtype=np.float32)
bbox_weights[labels == 1, :] = np.array(cfg.TRAIN.RPN_BBOX_WEIGHTS)
if DEBUG:
_sums = bbox_targets[labels == 1, :].sum(axis=0)
_squared_sums = (bbox_targets[labels == 1, :]**2).sum(axis=0)
_counts = np.sum(labels == 1)
means = _sums / (_counts + 1e-14)
stds = np.sqrt(_squared_sums / _counts - means**2)
print 'means', means
print 'stdevs', stds
# map up to original set of anchors
labels = _unmap(labels, total_anchors, inds_inside, fill=-1)
bbox_targets = _unmap(bbox_targets, total_anchors, inds_inside, fill=0)
bbox_weights = _unmap(bbox_weights, total_anchors, inds_inside, fill=0)
if DEBUG:
print 'rpn: max max_overlaps', np.max(max_overlaps)
print 'rpn: num_positives', np.sum(labels == 1)
print 'rpn: num_negatives', np.sum(labels == 0)
_fg_sum = np.sum(labels == 1)
_bg_sum = np.sum(labels == 0)
_count = 1
print 'rpn: num_positive avg', _fg_sum / _count
print 'rpn: num_negative avg', _bg_sum / _count
labels = labels.reshape(
(1, feat_height, feat_width, A)).transpose(0, 3, 1, 2)
labels = labels.reshape((1, A * feat_height * feat_width))
bbox_targets = bbox_targets.reshape(
(1, feat_height, feat_width, A * 4)).transpose(0, 3, 1, 2)
bbox_weights = bbox_weights.reshape(
(1, feat_height, feat_width, A * 4)).transpose((0, 3, 1, 2))
label = {
'label': labels,
'bbox_target': bbox_targets,
'bbox_weight': bbox_weights
}
return label
def assign_pyramid_anchor(
feat_shapes,
gt_boxes,
im_info,
cfg,
feat_strides=(4, 8, 16, 32, 64),
scales=(8, ),
ratios=(0.5, 1, 2),
allowed_border=0,
balance_scale_bg=False,
):
"""
assign ground truth boxes to anchor positions
:param feat_shapes: infer output shape
:param gt_boxes: assign ground truth
:param im_info: filter out anchors overlapped with edges
:param feat_strides: anchor position step
:param scales: used to generate anchors, affects num_anchors (per location)
:param ratios: aspect ratios of generated anchors
:param allowed_border: filter out anchors with edge overlap > allowed_border
:param balance_scale_bg: restrict the background samples for each pyramid level
:return: dict of label
'label': of shape (batch_size, 1) <- (batch_size, num_anchors, feat_height, feat_width)
'bbox_target': of shape (batch_size, num_anchors * 4, feat_height, feat_width)
'bbox_inside_weight': *todo* mark the assigned anchors
'bbox_outside_weight': used to normalize the bbox_loss, all weights sums to RPN_POSITIVE_WEIGHT
"""
def _unmap(data, count, inds, fill=0):
"""" unmap a subset inds of data into original data of size count """
if len(data.shape) == 1:
ret = np.empty((count, ), dtype=np.float32)
ret.fill(fill)
ret[inds] = data
else:
ret = np.empty((count, ) + data.shape[1:], dtype=np.float32)
ret.fill(fill)
ret[inds, :] = data
return ret
DEBUG = False
im_info = im_info[0]
scales = np.array(scales, dtype=np.float32)
ratios = np.array(ratios, dtype=np.float32)
assert (len(feat_shapes) == len(feat_strides))
fpn_args = []
fpn_anchors_fid = np.zeros(0).astype(int)
fpn_anchors = np.zeros([0, 4])
fpn_labels = np.zeros(0)
fpn_inds_inside = []
for feat_id in range(len(feat_strides)):
# len(scales.shape) == 1 just for backward compatibility, will remove in the future
if len(scales.shape) == 1:
base_anchors = generate_anchors(base_size=feat_strides[feat_id],
ratios=ratios,
scales=scales)
else:
assert len(scales.shape) == len(ratios.shape) == 2
base_anchors = generate_anchors(base_size=feat_strides[feat_id],
ratios=ratios[feat_id],
scales=scales[feat_id])
num_anchors = base_anchors.shape[0]
feat_height, feat_width = feat_shapes[feat_id][0][-2:]
# 1. generate proposals from bbox deltas and shifted anchors
shift_x = np.arange(0, feat_width) * feat_strides[feat_id]
shift_y = np.arange(0, feat_height) * feat_strides[feat_id]
shift_x, shift_y = np.meshgrid(shift_x, shift_y)
shifts = np.vstack((shift_x.ravel(), shift_y.ravel(), shift_x.ravel(),
shift_y.ravel())).transpose()
# add A anchors (1, A, 4) to
# cell K shifts (K, 1, 4) to get
# shift anchors (K, A, 4)
# reshape to (K*A, 4) shifted anchors
A = num_anchors
K = shifts.shape[0]
all_anchors = base_anchors.reshape((1, A, 4)) + shifts.reshape(
(1, K, 4)).transpose((1, 0, 2))
all_anchors = all_anchors.reshape((K * A, 4))
total_anchors = int(K * A)
# only keep anchors inside the image
inds_inside = np.where(
(all_anchors[:, 0] >= -allowed_border)
& (all_anchors[:, 1] >= -allowed_border)
& (all_anchors[:, 2] < im_info[1] + allowed_border)
& (all_anchors[:, 3] < im_info[0] + allowed_border))[0]
# keep only inside anchors
anchors = all_anchors[inds_inside, :]
# label: 1 is positive, 0 is negative, -1 is dont care
# for sigmoid classifier, ignore the 'background' class
labels = np.empty((len(inds_inside), ), dtype=np.float32)
labels.fill(-1)
fpn_anchors_fid = np.hstack((fpn_anchors_fid, len(inds_inside)))
fpn_anchors = np.vstack((fpn_anchors, anchors))
fpn_labels = np.hstack((fpn_labels, labels))
fpn_inds_inside.append(inds_inside)
fpn_args.append([feat_height, feat_width, A, total_anchors])
if gt_boxes.size > 0:
# overlap between the anchors and the gt boxes
# overlaps (ex, gt)
overlaps = bbox_overlaps(fpn_anchors.astype(np.float),
gt_boxes.astype(np.float))
argmax_overlaps = overlaps.argmax(axis=1)
max_overlaps = overlaps[np.arange(len(fpn_anchors)), argmax_overlaps]
gt_argmax_overlaps = overlaps.argmax(axis=0)
gt_max_overlaps = overlaps[gt_argmax_overlaps,
np.arange(overlaps.shape[1])]
gt_argmax_overlaps = np.where(overlaps == gt_max_overlaps)[0]
if not cfg.TRAIN.RPN_CLOBBER_POSITIVES:
# assign bg labels first so that positive labels can clobber them
fpn_labels[max_overlaps < cfg.TRAIN.RPN_NEGATIVE_OVERLAP] = 0
# fg label: for each gt, anchor with highest overlap
fpn_labels[gt_argmax_overlaps] = 1
# fg label: above threshold IoU
fpn_labels[max_overlaps >= cfg.TRAIN.RPN_POSITIVE_OVERLAP] = 1
if cfg.TRAIN.RPN_CLOBBER_POSITIVES:
# assign bg labels last so that negative labels can clobber positives
fpn_labels[max_overlaps < cfg.TRAIN.RPN_NEGATIVE_OVERLAP] = 0
else:
fpn_labels[:] = 0
# subsample positive labels if we have too many
num_fg = fpn_labels.shape[0] if cfg.TRAIN.RPN_BATCH_SIZE == -1 else int(
cfg.TRAIN.RPN_FG_FRACTION * cfg.TRAIN.RPN_BATCH_SIZE)
fg_inds = np.where(fpn_labels >= 1)[0]
if len(fg_inds) > num_fg:
disable_inds = npr.choice(fg_inds,
size=(len(fg_inds) - num_fg),
replace=False)
if DEBUG:
disable_inds = fg_inds[:(len(fg_inds) - num_fg)]
fpn_labels[disable_inds] = -1
# subsample negative labels if we have too many
num_bg = fpn_labels.shape[
0] if cfg.TRAIN.RPN_BATCH_SIZE == -1 else cfg.TRAIN.RPN_BATCH_SIZE - np.sum(
fpn_labels >= 1)
bg_inds = np.where(fpn_labels == 0)[0]
fpn_anchors_fid = np.hstack((0, fpn_anchors_fid.cumsum()))
if balance_scale_bg:
num_bg_scale = num_bg / len(feat_strides)
for feat_id in range(0, len(feat_strides)):
bg_ind_scale = bg_inds[(bg_inds >= fpn_anchors_fid[feat_id])
& (bg_inds < fpn_anchors_fid[feat_id + 1])]
if len(bg_ind_scale) > num_bg_scale:
disable_inds = npr.choice(bg_ind_scale,
size=(len(bg_ind_scale) -
num_bg_scale),
replace=False)
fpn_labels[disable_inds] = -1
else:
if len(bg_inds) > num_bg:
disable_inds = npr.choice(bg_inds,
size=(len(bg_inds) - num_bg),
replace=False)
if DEBUG:
disable_inds = bg_inds[:(len(bg_inds) - num_bg)]
fpn_labels[disable_inds] = -1
fpn_bbox_targets = np.zeros((len(fpn_anchors), 4), dtype=np.float32)
if gt_boxes.size > 0:
fpn_bbox_targets[fpn_labels >= 1, :] = bbox_transform(
fpn_anchors[fpn_labels >= 1, :],
gt_boxes[argmax_overlaps[fpn_labels >= 1], :4])
# fpn_bbox_targets[:] = bbox_transform(fpn_anchors, gt_boxes[argmax_overlaps, :4])
# fpn_bbox_targets = (fpn_bbox_targets - np.array(cfg.TRAIN.BBOX_MEANS)) / np.array(cfg.TRAIN.BBOX_STDS)
fpn_bbox_weights = np.zeros((len(fpn_anchors), 4), dtype=np.float32)
fpn_bbox_weights[fpn_labels >= 1, :] = np.array(cfg.TRAIN.RPN_BBOX_WEIGHTS)
label_list = []
bbox_target_list = []
bbox_weight_list = []
for feat_id in range(0, len(feat_strides)):
feat_height, feat_width, A, total_anchors = fpn_args[feat_id]
# map up to original set of anchors
labels = _unmap(
fpn_labels[fpn_anchors_fid[feat_id]:fpn_anchors_fid[feat_id + 1]],
total_anchors,
fpn_inds_inside[feat_id],
fill=-1)
bbox_targets = _unmap(
fpn_bbox_targets[fpn_anchors_fid[feat_id]:fpn_anchors_fid[feat_id +
1]],
total_anchors,
fpn_inds_inside[feat_id],
fill=0)
bbox_weights = _unmap(
fpn_bbox_weights[fpn_anchors_fid[feat_id]:fpn_anchors_fid[feat_id +
1]],
total_anchors,
fpn_inds_inside[feat_id],
fill=0)
labels = labels.reshape(
(1, feat_height, feat_width, A)).transpose(0, 3, 1, 2)
labels = labels.reshape((1, A * feat_height * feat_width))
bbox_targets = bbox_targets.reshape(
(1, feat_height, feat_width, A * 4)).transpose(0, 3, 1, 2)
bbox_targets = bbox_targets.reshape((1, A * 4, -1))
bbox_weights = bbox_weights.reshape(
(1, feat_height, feat_width, A * 4)).transpose((0, 3, 1, 2))
bbox_weights = bbox_weights.reshape((1, A * 4, -1))
label_list.append(labels)
bbox_target_list.append(bbox_targets)
bbox_weight_list.append(bbox_weights)
# label.update({'label_p' + str(feat_id + feat_id_start): labels,
# 'bbox_target_p' + str(feat_id + feat_id_start): bbox_targets,
# 'bbox_weight_p' + str(feat_id + feat_id_start): bbox_weights})
label = {
'label': np.concatenate(label_list, axis=1),
'bbox_target': np.concatenate(bbox_target_list, axis=2),
'bbox_weight': np.concatenate(bbox_weight_list, axis=2)
}
return label