def __init__(self,
num_classes,
in_channels,
feat_channels=256,
stacked_convs=2,
strides=[8, 16, 32],
use_depthwise=False,
dcn_on_last_conv=False,
conv_bias='auto',
conv_cfg=None,
norm_cfg=dict(type='BN', momentum=0.03, eps=0.001),
act_cfg=dict(type='Swish'),
loss_cls=dict(type='CrossEntropyLoss',
use_sigmoid=True,
reduction='sum',
loss_weight=1.0),
loss_bbox=dict(type='IoULoss',
mode='square',
eps=1e-16,
reduction='sum',
loss_weight=5.0),
loss_obj=dict(type='CrossEntropyLoss',
use_sigmoid=True,
reduction='sum',
loss_weight=1.0),
loss_l1=dict(type='L1Loss', reduction='sum', loss_weight=1.0),
train_cfg=None,
test_cfg=None,
init_cfg=dict(type='Kaiming',
layer='Conv2d',
a=math.sqrt(5),
distribution='uniform',
mode='fan_in',
nonlinearity='leaky_relu')):
super().__init__(init_cfg=init_cfg)
self.num_classes = num_classes
self.cls_out_channels = num_classes
self.in_channels = in_channels
self.feat_channels = feat_channels
self.stacked_convs = stacked_convs
self.strides = strides
self.use_depthwise = use_depthwise
self.dcn_on_last_conv = dcn_on_last_conv
assert conv_bias == 'auto' or isinstance(conv_bias, bool)
self.conv_bias = conv_bias
self.use_sigmoid_cls = True
self.conv_cfg = conv_cfg
self.norm_cfg = norm_cfg
self.act_cfg = act_cfg
self.loss_cls = build_loss(loss_cls)
self.loss_bbox = build_loss(loss_bbox)
self.loss_obj = build_loss(loss_obj)
self.use_l1 = False # This flag will be modified by hooks.
self.loss_l1 = build_loss(loss_l1)
self.prior_generator = MlvlPointGenerator(strides, offset=0)
self.test_cfg = test_cfg
self.train_cfg = train_cfg
self.sampling = False
if self.train_cfg:
self.assigner = build_assigner(self.train_cfg.assigner)
# sampling=False so use PseudoSampler
sampler_cfg = dict(type='PseudoSampler')
self.sampler = build_sampler(sampler_cfg, context=self)
self.fp16_enabled = False
self._init_layers()
def __init__(self,
num_classes,
in_channels,
regress_ranges=((-1, 64), (64, 128), (128, 256), (256, 512),
(512, INF)),
center_sampling=False,
center_sample_radius=1.5,
sync_num_pos=True,
gradient_mul=0.1,
bbox_norm_type='reg_denom',
loss_cls_fl=dict(
type='FocalLoss',
use_sigmoid=True,
gamma=2.0,
alpha=0.25,
loss_weight=1.0),
use_vfl=True,
loss_cls=dict(
type='VarifocalLoss',
use_sigmoid=True,
alpha=0.75,
gamma=2.0,
iou_weighted=True,
loss_weight=1.0),
loss_bbox=dict(type='GIoULoss', loss_weight=1.5),
loss_bbox_refine=dict(type='GIoULoss', loss_weight=2.0),
norm_cfg=dict(type='GN', num_groups=32, requires_grad=True),
use_atss=True,
reg_decoded_bbox=True,
anchor_generator=dict(
type='AnchorGenerator',
ratios=[1.0],
octave_base_scale=8,
scales_per_octave=1,
center_offset=0.0,
strides=[8, 16, 32, 64, 128]),
init_cfg=dict(
type='Normal',
layer='Conv2d',
std=0.01,
override=dict(
type='Normal',
name='vfnet_cls',
std=0.01,
bias_prob=0.01)),
**kwargs):
# dcn base offsets, adapted from reppoints_head.py
self.num_dconv_points = 9
self.dcn_kernel = int(np.sqrt(self.num_dconv_points))
self.dcn_pad = int((self.dcn_kernel - 1) / 2)
dcn_base = np.arange(-self.dcn_pad,
self.dcn_pad + 1).astype(np.float64)
dcn_base_y = np.repeat(dcn_base, self.dcn_kernel)
dcn_base_x = np.tile(dcn_base, self.dcn_kernel)
dcn_base_offset = np.stack([dcn_base_y, dcn_base_x], axis=1).reshape(
(-1))
self.dcn_base_offset = torch.tensor(dcn_base_offset).view(1, -1, 1, 1)
super(FCOSHead, self).__init__(
num_classes,
in_channels,
norm_cfg=norm_cfg,
init_cfg=init_cfg,
**kwargs)
self.regress_ranges = regress_ranges
self.reg_denoms = [
regress_range[-1] for regress_range in regress_ranges
]
self.reg_denoms[-1] = self.reg_denoms[-2] * 2
self.center_sampling = center_sampling
self.center_sample_radius = center_sample_radius
self.sync_num_pos = sync_num_pos
self.bbox_norm_type = bbox_norm_type
self.gradient_mul = gradient_mul
self.use_vfl = use_vfl
if self.use_vfl:
self.loss_cls = build_loss(loss_cls)
else:
self.loss_cls = build_loss(loss_cls_fl)
self.loss_bbox = build_loss(loss_bbox)
self.loss_bbox_refine = build_loss(loss_bbox_refine)
# for getting ATSS targets
self.use_atss = use_atss
self.reg_decoded_bbox = reg_decoded_bbox
self.use_sigmoid_cls = loss_cls.get('use_sigmoid', False)
self.anchor_center_offset = anchor_generator['center_offset']
self.num_base_priors = self.prior_generator.num_base_priors[0]
self.sampling = False
if self.train_cfg:
self.assigner = build_assigner(self.train_cfg.assigner)
sampler_cfg = dict(type='PseudoSampler')
self.sampler = build_sampler(sampler_cfg, context=self)
# only be used in `get_atss_targets` when `use_atss` is True
self.atss_prior_generator = build_prior_generator(anchor_generator)
self.fcos_prior_generator = MlvlPointGenerator(
anchor_generator['strides'],
self.anchor_center_offset if self.use_atss else 0.5)
# In order to reuse the `get_bboxes` in `BaseDenseHead.
# Only be used in testing phase.
self.prior_generator = self.fcos_prior_generator
class YOLOXHead(BaseDenseHead, BBoxTestMixin):
"""YOLOXHead head used in `YOLOX <https://arxiv.org/abs/2107.08430>`_.
Args:
num_classes (int): Number of categories excluding the background
category.
in_channels (int): Number of channels in the input feature map.
feat_channels (int): Number of hidden channels in stacking convs.
Default: 256
stacked_convs (int): Number of stacking convs of the head.
Default: 2.
strides (tuple): Downsample factor of each feature map.
use_depthwise (bool): Whether to depthwise separable convolution in
blocks. Default: False
dcn_on_last_conv (bool): If true, use dcn in the last layer of
towers. Default: False.
conv_bias (bool | str): If specified as `auto`, it will be decided by
the norm_cfg. Bias of conv will be set as True if `norm_cfg` is
None, otherwise False. Default: "auto".
conv_cfg (dict): Config dict for convolution layer. Default: None.
norm_cfg (dict): Config dict for normalization layer. Default: None.
act_cfg (dict): Config dict for activation layer. Default: None.
loss_cls (dict): Config of classification loss.
loss_bbox (dict): Config of localization loss.
loss_obj (dict): Config of objectness loss.
loss_l1 (dict): Config of L1 loss.
train_cfg (dict): Training config of anchor head.
test_cfg (dict): Testing config of anchor head.
init_cfg (dict or list[dict], optional): Initialization config dict.
"""
def __init__(self,
num_classes,
in_channels,
feat_channels=256,
stacked_convs=2,
strides=[8, 16, 32],
use_depthwise=False,
dcn_on_last_conv=False,
conv_bias='auto',
conv_cfg=None,
norm_cfg=dict(type='BN', momentum=0.03, eps=0.001),
act_cfg=dict(type='Swish'),
loss_cls=dict(type='CrossEntropyLoss',
use_sigmoid=True,
reduction='sum',
loss_weight=1.0),
loss_bbox=dict(type='IoULoss',
mode='square',
eps=1e-16,
reduction='sum',
loss_weight=5.0),
loss_obj=dict(type='CrossEntropyLoss',
use_sigmoid=True,
reduction='sum',
loss_weight=1.0),
loss_l1=dict(type='L1Loss', reduction='sum', loss_weight=1.0),
train_cfg=None,
test_cfg=None,
init_cfg=dict(type='Kaiming',
layer='Conv2d',
a=math.sqrt(5),
distribution='uniform',
mode='fan_in',
nonlinearity='leaky_relu')):
super().__init__(init_cfg=init_cfg)
self.num_classes = num_classes
self.cls_out_channels = num_classes
self.in_channels = in_channels
self.feat_channels = feat_channels
self.stacked_convs = stacked_convs
self.strides = strides
self.use_depthwise = use_depthwise
self.dcn_on_last_conv = dcn_on_last_conv
assert conv_bias == 'auto' or isinstance(conv_bias, bool)
self.conv_bias = conv_bias
self.use_sigmoid_cls = True
self.conv_cfg = conv_cfg
self.norm_cfg = norm_cfg
self.act_cfg = act_cfg
self.loss_cls = build_loss(loss_cls)
self.loss_bbox = build_loss(loss_bbox)
self.loss_obj = build_loss(loss_obj)
self.use_l1 = False # This flag will be modified by hooks.
self.loss_l1 = build_loss(loss_l1)
self.prior_generator = MlvlPointGenerator(strides, offset=0)
self.test_cfg = test_cfg
self.train_cfg = train_cfg
self.sampling = False
if self.train_cfg:
self.assigner = build_assigner(self.train_cfg.assigner)
# sampling=False so use PseudoSampler
sampler_cfg = dict(type='PseudoSampler')
self.sampler = build_sampler(sampler_cfg, context=self)
self.fp16_enabled = False
self._init_layers()
def _init_layers(self):
self.multi_level_cls_convs = nn.ModuleList()
self.multi_level_reg_convs = nn.ModuleList()
self.multi_level_conv_cls = nn.ModuleList()
self.multi_level_conv_reg = nn.ModuleList()
self.multi_level_conv_obj = nn.ModuleList()
for _ in self.strides:
self.multi_level_cls_convs.append(self._build_stacked_convs())
self.multi_level_reg_convs.append(self._build_stacked_convs())
conv_cls, conv_reg, conv_obj = self._build_predictor()
self.multi_level_conv_cls.append(conv_cls)
self.multi_level_conv_reg.append(conv_reg)
self.multi_level_conv_obj.append(conv_obj)
def _build_stacked_convs(self):
"""Initialize conv layers of a single level head."""
conv = DepthwiseSeparableConvModule \
if self.use_depthwise else ConvModule
stacked_convs = []
for i in range(self.stacked_convs):
chn = self.in_channels if i == 0 else self.feat_channels
if self.dcn_on_last_conv and i == self.stacked_convs - 1:
conv_cfg = dict(type='DCNv2')
else:
conv_cfg = self.conv_cfg
stacked_convs.append(
conv(chn,
self.feat_channels,
3,
stride=1,
padding=1,
conv_cfg=conv_cfg,
norm_cfg=self.norm_cfg,
act_cfg=self.act_cfg,
bias=self.conv_bias))
return nn.Sequential(*stacked_convs)
def _build_predictor(self):
"""Initialize predictor layers of a single level head."""
conv_cls = nn.Conv2d(self.feat_channels, self.cls_out_channels, 1)
conv_reg = nn.Conv2d(self.feat_channels, 4, 1)
conv_obj = nn.Conv2d(self.feat_channels, 1, 1)
return conv_cls, conv_reg, conv_obj
def init_weights(self):
super(YOLOXHead, self).init_weights()
# Use prior in model initialization to improve stability
bias_init = bias_init_with_prob(0.01)
for conv_cls, conv_obj in zip(self.multi_level_conv_cls,
self.multi_level_conv_obj):
conv_cls.bias.data.fill_(bias_init)
conv_obj.bias.data.fill_(bias_init)
def forward_single(self, x, cls_convs, reg_convs, conv_cls, conv_reg,
conv_obj):
"""Forward feature of a single scale level."""
cls_feat = cls_convs(x)
reg_feat = reg_convs(x)
cls_score = conv_cls(cls_feat)
bbox_pred = conv_reg(reg_feat)
objectness = conv_obj(reg_feat)
return cls_score, bbox_pred, objectness
def forward(self, feats):
"""Forward features from the upstream network.
Args:
feats (tuple[Tensor]): Features from the upstream network, each is
a 4D-tensor.
Returns:
tuple[Tensor]: A tuple of multi-level predication map, each is a
4D-tensor of shape (batch_size, 5+num_classes, height, width).
"""
return multi_apply(self.forward_single, feats,
self.multi_level_cls_convs,
self.multi_level_reg_convs,
self.multi_level_conv_cls,
self.multi_level_conv_reg,
self.multi_level_conv_obj)
@force_fp32(apply_to=('cls_scores', 'bbox_preds', 'objectnesses'))
def get_bboxes(self,
cls_scores,
bbox_preds,
objectnesses,
img_metas=None,
cfg=None,
rescale=False,
with_nms=True):
"""Transform network outputs of a batch into bbox results.
Args:
cls_scores (list[Tensor]): Classification scores for all
scale levels, each is a 4D-tensor, has shape
(batch_size, num_priors * num_classes, H, W).
bbox_preds (list[Tensor]): Box energies / deltas for all
scale levels, each is a 4D-tensor, has shape
(batch_size, num_priors * 4, H, W).
objectnesses (list[Tensor], Optional): Score factor for
all scale level, each is a 4D-tensor, has shape
(batch_size, 1, H, W).
img_metas (list[dict], Optional): Image meta info. Default None.
cfg (mmcv.Config, Optional): Test / postprocessing configuration,
if None, test_cfg would be used. Default None.
rescale (bool): If True, return boxes in original image space.
Default False.
with_nms (bool): If True, do nms before return boxes.
Default True.
Returns:
list[list[Tensor, Tensor]]: Each item in result_list is 2-tuple.
The first item is an (n, 5) tensor, where the first 4 columns
are bounding box positions (tl_x, tl_y, br_x, br_y) and the
5-th column is a score between 0 and 1. The second item is a
(n,) tensor where each item is the predicted class label of
the corresponding box.
"""
assert len(cls_scores) == len(bbox_preds) == len(objectnesses)
cfg = self.test_cfg if cfg is None else cfg
scale_factors = np.array(
[img_meta['scale_factor'] for img_meta in img_metas])
num_imgs = len(img_metas)
featmap_sizes = [cls_score.shape[2:] for cls_score in cls_scores]
mlvl_priors = self.prior_generator.grid_priors(
featmap_sizes,
dtype=cls_scores[0].dtype,
device=cls_scores[0].device,
with_stride=True)
# flatten cls_scores, bbox_preds and objectness
flatten_cls_scores = [
cls_score.permute(0, 2, 3, 1).reshape(num_imgs, -1,
self.cls_out_channels)
for cls_score in cls_scores
]
flatten_bbox_preds = [
bbox_pred.permute(0, 2, 3, 1).reshape(num_imgs, -1, 4)
for bbox_pred in bbox_preds
]
flatten_objectness = [
objectness.permute(0, 2, 3, 1).reshape(num_imgs, -1)
for objectness in objectnesses
]
flatten_cls_scores = torch.cat(flatten_cls_scores, dim=1).sigmoid()
flatten_bbox_preds = torch.cat(flatten_bbox_preds, dim=1)
flatten_objectness = torch.cat(flatten_objectness, dim=1).sigmoid()
flatten_priors = torch.cat(mlvl_priors)
flatten_bboxes = self._bbox_decode(flatten_priors, flatten_bbox_preds)
if rescale:
flatten_bboxes[..., :4] /= flatten_bboxes.new_tensor(
scale_factors).unsqueeze(1)
result_list = []
for img_id in range(len(img_metas)):
cls_scores = flatten_cls_scores[img_id]
score_factor = flatten_objectness[img_id]
bboxes = flatten_bboxes[img_id]
result_list.append(
self._bboxes_nms(cls_scores, bboxes, score_factor, cfg))
return result_list
def _bbox_decode(self, priors, bbox_preds):
xys = (bbox_preds[..., :2] * priors[:, 2:]) + priors[:, :2]
whs = bbox_preds[..., 2:].exp() * priors[:, 2:]
tl_x = (xys[..., 0] - whs[..., 0] / 2)
tl_y = (xys[..., 1] - whs[..., 1] / 2)
br_x = (xys[..., 0] + whs[..., 0] / 2)
br_y = (xys[..., 1] + whs[..., 1] / 2)
decoded_bboxes = torch.stack([tl_x, tl_y, br_x, br_y], -1)
return decoded_bboxes
def _bboxes_nms(self, cls_scores, bboxes, score_factor, cfg):
max_scores, labels = torch.max(cls_scores, 1)
valid_mask = score_factor * max_scores >= cfg.score_thr
bboxes = bboxes[valid_mask]
scores = max_scores[valid_mask] * score_factor[valid_mask]
labels = labels[valid_mask]
if labels.numel() == 0:
return bboxes, labels
else:
dets, keep = batched_nms(bboxes, scores, labels, cfg.nms)
return dets, labels[keep]
@force_fp32(apply_to=('cls_scores', 'bbox_preds', 'objectnesses'))
def loss(self,
cls_scores,
bbox_preds,
objectnesses,
gt_bboxes,
gt_labels,
img_metas,
gt_bboxes_ignore=None):
"""Compute loss of the head.
Args:
cls_scores (list[Tensor]): Box scores for each scale level,
each is a 4D-tensor, the channel number is
num_priors * num_classes.
bbox_preds (list[Tensor]): Box energies / deltas for each scale
level, each is a 4D-tensor, the channel number is
num_priors * 4.
objectnesses (list[Tensor], Optional): Score factor for
all scale level, each is a 4D-tensor, has shape
(batch_size, 1, H, W).
gt_bboxes (list[Tensor]): Ground truth bboxes for each image with
shape (num_gts, 4) in [tl_x, tl_y, br_x, br_y] format.
gt_labels (list[Tensor]): class indices corresponding to each box
img_metas (list[dict]): Meta information of each image, e.g.,
image size, scaling factor, etc.
gt_bboxes_ignore (None | list[Tensor]): specify which bounding
boxes can be ignored when computing the loss.
"""
num_imgs = len(img_metas)
featmap_sizes = [cls_score.shape[2:] for cls_score in cls_scores]
mlvl_priors = self.prior_generator.grid_priors(
featmap_sizes,
dtype=cls_scores[0].dtype,
device=cls_scores[0].device,
with_stride=True)
flatten_cls_preds = [
cls_pred.permute(0, 2, 3, 1).reshape(num_imgs, -1,
self.cls_out_channels)
for cls_pred in cls_scores
]
flatten_bbox_preds = [
bbox_pred.permute(0, 2, 3, 1).reshape(num_imgs, -1, 4)
for bbox_pred in bbox_preds
]
flatten_objectness = [
objectness.permute(0, 2, 3, 1).reshape(num_imgs, -1)
for objectness in objectnesses
]
flatten_cls_preds = torch.cat(flatten_cls_preds, dim=1)
flatten_bbox_preds = torch.cat(flatten_bbox_preds, dim=1)
flatten_objectness = torch.cat(flatten_objectness, dim=1)
flatten_priors = torch.cat(mlvl_priors)
flatten_bboxes = self._bbox_decode(flatten_priors, flatten_bbox_preds)
(pos_masks, cls_targets, obj_targets, bbox_targets, l1_targets,
num_fg_imgs) = multi_apply(
self._get_target_single, flatten_cls_preds.detach(),
flatten_objectness.detach(),
flatten_priors.unsqueeze(0).repeat(num_imgs, 1, 1),
flatten_bboxes.detach(), gt_bboxes, gt_labels)
# The experimental results show that ‘reduce_mean’ can improve
# performance on the COCO dataset.
num_pos = torch.tensor(sum(num_fg_imgs),
dtype=torch.float,
device=flatten_cls_preds.device)
num_total_samples = max(reduce_mean(num_pos), 1.0)
pos_masks = torch.cat(pos_masks, 0)
cls_targets = torch.cat(cls_targets, 0)
obj_targets = torch.cat(obj_targets, 0)
bbox_targets = torch.cat(bbox_targets, 0)
if self.use_l1:
l1_targets = torch.cat(l1_targets, 0)
loss_bbox = self.loss_bbox(
flatten_bboxes.view(-1, 4)[pos_masks],
bbox_targets) / num_total_samples
loss_obj = self.loss_obj(flatten_objectness.view(-1, 1),
obj_targets) / num_total_samples
loss_cls = self.loss_cls(
flatten_cls_preds.view(-1, self.num_classes)[pos_masks],
cls_targets) / num_total_samples
loss_dict = dict(loss_cls=loss_cls,
loss_bbox=loss_bbox,
loss_obj=loss_obj)
if self.use_l1:
loss_l1 = self.loss_l1(
flatten_bbox_preds.view(-1, 4)[pos_masks],
l1_targets) / num_total_samples
loss_dict.update(loss_l1=loss_l1)
return loss_dict
@torch.no_grad()
def _get_target_single(self, cls_preds, objectness, priors, decoded_bboxes,
gt_bboxes, gt_labels):
"""Compute classification, regression, and objectness targets for
priors in a single image.
Args:
cls_preds (Tensor): Classification predictions of one image,
a 2D-Tensor with shape [num_priors, num_classes]
objectness (Tensor): Objectness predictions of one image,
a 1D-Tensor with shape [num_priors]
priors (Tensor): All priors of one image, a 2D-Tensor with shape
[num_priors, 4] in [cx, xy, stride_w, stride_y] format.
decoded_bboxes (Tensor): Decoded bboxes predictions of one image,
a 2D-Tensor with shape [num_priors, 4] in [tl_x, tl_y,
br_x, br_y] format.
gt_bboxes (Tensor): Ground truth bboxes of one image, a 2D-Tensor
with shape [num_gts, 4] in [tl_x, tl_y, br_x, br_y] format.
gt_labels (Tensor): Ground truth labels of one image, a Tensor
with shape [num_gts].
"""
num_priors = priors.size(0)
num_gts = gt_labels.size(0)
gt_bboxes = gt_bboxes.to(decoded_bboxes.dtype)
# No target
if num_gts == 0:
cls_target = cls_preds.new_zeros((0, self.num_classes))
bbox_target = cls_preds.new_zeros((0, 4))
l1_target = cls_preds.new_zeros((0, 4))
obj_target = cls_preds.new_zeros((num_priors, 1))
foreground_mask = cls_preds.new_zeros(num_priors).bool()
return (foreground_mask, cls_target, obj_target, bbox_target,
l1_target, 0)
# YOLOX uses center priors with 0.5 offset to assign targets,
# but use center priors without offset to regress bboxes.
offset_priors = torch.cat(
[priors[:, :2] + priors[:, 2:] * 0.5, priors[:, 2:]], dim=-1)
assign_result = self.assigner.assign(
cls_preds.sigmoid() * objectness.unsqueeze(1).sigmoid(),
offset_priors, decoded_bboxes, gt_bboxes, gt_labels)
sampling_result = self.sampler.sample(assign_result, priors, gt_bboxes)
pos_inds = sampling_result.pos_inds
num_pos_per_img = pos_inds.size(0)
pos_ious = assign_result.max_overlaps[pos_inds]
# IOU aware classification score
cls_target = F.one_hot(sampling_result.pos_gt_labels,
self.num_classes) * pos_ious.unsqueeze(-1)
obj_target = torch.zeros_like(objectness).unsqueeze(-1)
obj_target[pos_inds] = 1
bbox_target = sampling_result.pos_gt_bboxes
l1_target = cls_preds.new_zeros((num_pos_per_img, 4))
if self.use_l1:
l1_target = self._get_l1_target(l1_target, bbox_target,
priors[pos_inds])
foreground_mask = torch.zeros_like(objectness).to(torch.bool)
foreground_mask[pos_inds] = 1
return (foreground_mask, cls_target, obj_target, bbox_target,
l1_target, num_pos_per_img)
def _get_l1_target(self, l1_target, gt_bboxes, priors, eps=1e-8):
"""Convert gt bboxes to center offset and log width height."""
gt_cxcywh = bbox_xyxy_to_cxcywh(gt_bboxes)
l1_target[:, :2] = (gt_cxcywh[:, :2] - priors[:, :2]) / priors[:, 2:]
l1_target[:, 2:] = torch.log(gt_cxcywh[:, 2:] / priors[:, 2:] + eps)
return l1_target
class VFNetHead(ATSSHead, FCOSHead):
"""Head of `VarifocalNet (VFNet): An IoU-aware Dense Object
Detector.<https://arxiv.org/abs/2008.13367>`_.
The VFNet predicts IoU-aware classification scores which mix the
object presence confidence and object localization accuracy as the
detection score. It is built on the FCOS architecture and uses ATSS
for defining positive/negative training examples. The VFNet is trained
with Varifocal Loss and empolys star-shaped deformable convolution to
extract features for a bbox.
Args:
num_classes (int): Number of categories excluding the background
category.
in_channels (int): Number of channels in the input feature map.
regress_ranges (tuple[tuple[int, int]]): Regress range of multiple
level points.
center_sampling (bool): If true, use center sampling. Default: False.
center_sample_radius (float): Radius of center sampling. Default: 1.5.
sync_num_pos (bool): If true, synchronize the number of positive
examples across GPUs. Default: True
gradient_mul (float): The multiplier to gradients from bbox refinement
and recognition. Default: 0.1.
bbox_norm_type (str): The bbox normalization type, 'reg_denom' or
'stride'. Default: reg_denom
loss_cls_fl (dict): Config of focal loss.
use_vfl (bool): If true, use varifocal loss for training.
Default: True.
loss_cls (dict): Config of varifocal loss.
loss_bbox (dict): Config of localization loss, GIoU Loss.
loss_bbox (dict): Config of localization refinement loss, GIoU Loss.
norm_cfg (dict): dictionary to construct and config norm layer.
Default: norm_cfg=dict(type='GN', num_groups=32,
requires_grad=True).
use_atss (bool): If true, use ATSS to define positive/negative
examples. Default: True.
anchor_generator (dict): Config of anchor generator for ATSS.
init_cfg (dict or list[dict], optional): Initialization config dict.
Example:
>>> self = VFNetHead(11, 7)
>>> feats = [torch.rand(1, 7, s, s) for s in [4, 8, 16, 32, 64]]
>>> cls_score, bbox_pred, bbox_pred_refine= self.forward(feats)
>>> assert len(cls_score) == len(self.scales)
""" # noqa: E501
def __init__(self,
num_classes,
in_channels,
regress_ranges=((-1, 64), (64, 128), (128, 256), (256, 512),
(512, INF)),
center_sampling=False,
center_sample_radius=1.5,
sync_num_pos=True,
gradient_mul=0.1,
bbox_norm_type='reg_denom',
loss_cls_fl=dict(
type='FocalLoss',
use_sigmoid=True,
gamma=2.0,
alpha=0.25,
loss_weight=1.0),
use_vfl=True,
loss_cls=dict(
type='VarifocalLoss',
use_sigmoid=True,
alpha=0.75,
gamma=2.0,
iou_weighted=True,
loss_weight=1.0),
loss_bbox=dict(type='GIoULoss', loss_weight=1.5),
loss_bbox_refine=dict(type='GIoULoss', loss_weight=2.0),
norm_cfg=dict(type='GN', num_groups=32, requires_grad=True),
use_atss=True,
reg_decoded_bbox=True,
anchor_generator=dict(
type='AnchorGenerator',
ratios=[1.0],
octave_base_scale=8,
scales_per_octave=1,
center_offset=0.0,
strides=[8, 16, 32, 64, 128]),
init_cfg=dict(
type='Normal',
layer='Conv2d',
std=0.01,
override=dict(
type='Normal',
name='vfnet_cls',
std=0.01,
bias_prob=0.01)),
**kwargs):
# dcn base offsets, adapted from reppoints_head.py
self.num_dconv_points = 9
self.dcn_kernel = int(np.sqrt(self.num_dconv_points))
self.dcn_pad = int((self.dcn_kernel - 1) / 2)
dcn_base = np.arange(-self.dcn_pad,
self.dcn_pad + 1).astype(np.float64)
dcn_base_y = np.repeat(dcn_base, self.dcn_kernel)
dcn_base_x = np.tile(dcn_base, self.dcn_kernel)
dcn_base_offset = np.stack([dcn_base_y, dcn_base_x], axis=1).reshape(
(-1))
self.dcn_base_offset = torch.tensor(dcn_base_offset).view(1, -1, 1, 1)
super(FCOSHead, self).__init__(
num_classes,
in_channels,
norm_cfg=norm_cfg,
init_cfg=init_cfg,
**kwargs)
self.regress_ranges = regress_ranges
self.reg_denoms = [
regress_range[-1] for regress_range in regress_ranges
]
self.reg_denoms[-1] = self.reg_denoms[-2] * 2
self.center_sampling = center_sampling
self.center_sample_radius = center_sample_radius
self.sync_num_pos = sync_num_pos
self.bbox_norm_type = bbox_norm_type
self.gradient_mul = gradient_mul
self.use_vfl = use_vfl
if self.use_vfl:
self.loss_cls = build_loss(loss_cls)
else:
self.loss_cls = build_loss(loss_cls_fl)
self.loss_bbox = build_loss(loss_bbox)
self.loss_bbox_refine = build_loss(loss_bbox_refine)
# for getting ATSS targets
self.use_atss = use_atss
self.reg_decoded_bbox = reg_decoded_bbox
self.use_sigmoid_cls = loss_cls.get('use_sigmoid', False)
self.anchor_center_offset = anchor_generator['center_offset']
self.num_base_priors = self.prior_generator.num_base_priors[0]
self.sampling = False
if self.train_cfg:
self.assigner = build_assigner(self.train_cfg.assigner)
sampler_cfg = dict(type='PseudoSampler')
self.sampler = build_sampler(sampler_cfg, context=self)
# only be used in `get_atss_targets` when `use_atss` is True
self.atss_prior_generator = build_prior_generator(anchor_generator)
self.fcos_prior_generator = MlvlPointGenerator(
anchor_generator['strides'],
self.anchor_center_offset if self.use_atss else 0.5)
# In order to reuse the `get_bboxes` in `BaseDenseHead.
# Only be used in testing phase.
self.prior_generator = self.fcos_prior_generator
@property
def num_anchors(self):
"""
Returns:
int: Number of anchors on each point of feature map.
"""
warnings.warn('DeprecationWarning: `num_anchors` is deprecated, '
'please use "num_base_priors" instead')
return self.num_base_priors
@property
def anchor_generator(self):
warnings.warn('DeprecationWarning: anchor_generator is deprecated, '
'please use "atss_prior_generator" instead')
return self.prior_generator
def _init_layers(self):
"""Initialize layers of the head."""
super(FCOSHead, self)._init_cls_convs()
super(FCOSHead, self)._init_reg_convs()
self.relu = nn.ReLU(inplace=True)
self.vfnet_reg_conv = ConvModule(
self.feat_channels,
self.feat_channels,
3,
stride=1,
padding=1,
conv_cfg=self.conv_cfg,
norm_cfg=self.norm_cfg,
bias=self.conv_bias)
self.vfnet_reg = nn.Conv2d(self.feat_channels, 4, 3, padding=1)
self.scales = nn.ModuleList([Scale(1.0) for _ in self.strides])
self.vfnet_reg_refine_dconv = DeformConv2d(
self.feat_channels,
self.feat_channels,
self.dcn_kernel,
1,
padding=self.dcn_pad)
self.vfnet_reg_refine = nn.Conv2d(self.feat_channels, 4, 3, padding=1)
self.scales_refine = nn.ModuleList([Scale(1.0) for _ in self.strides])
self.vfnet_cls_dconv = DeformConv2d(
self.feat_channels,
self.feat_channels,
self.dcn_kernel,
1,
padding=self.dcn_pad)
self.vfnet_cls = nn.Conv2d(
self.feat_channels, self.cls_out_channels, 3, padding=1)
def forward(self, feats):
"""Forward features from the upstream network.
Args:
feats (tuple[Tensor]): Features from the upstream network, each is
a 4D-tensor.
Returns:
tuple:
cls_scores (list[Tensor]): Box iou-aware scores for each scale
level, each is a 4D-tensor, the channel number is
num_points * num_classes.
bbox_preds (list[Tensor]): Box offsets for each
scale level, each is a 4D-tensor, the channel number is
num_points * 4.
bbox_preds_refine (list[Tensor]): Refined Box offsets for
each scale level, each is a 4D-tensor, the channel
number is num_points * 4.
"""
return multi_apply(self.forward_single, feats, self.scales,
self.scales_refine, self.strides, self.reg_denoms)
def forward_single(self, x, scale, scale_refine, stride, reg_denom):
"""Forward features of a single scale level.
Args:
x (Tensor): FPN feature maps of the specified stride.
scale (:obj: `mmcv.cnn.Scale`): Learnable scale module to resize
the bbox prediction.
scale_refine (:obj: `mmcv.cnn.Scale`): Learnable scale module to
resize the refined bbox prediction.
stride (int): The corresponding stride for feature maps,
used to normalize the bbox prediction when
bbox_norm_type = 'stride'.
reg_denom (int): The corresponding regression range for feature
maps, only used to normalize the bbox prediction when
bbox_norm_type = 'reg_denom'.
Returns:
tuple: iou-aware cls scores for each box, bbox predictions and
refined bbox predictions of input feature maps.
"""
cls_feat = x
reg_feat = x
for cls_layer in self.cls_convs:
cls_feat = cls_layer(cls_feat)
for reg_layer in self.reg_convs:
reg_feat = reg_layer(reg_feat)
# predict the bbox_pred of different level
reg_feat_init = self.vfnet_reg_conv(reg_feat)
if self.bbox_norm_type == 'reg_denom':
bbox_pred = scale(
self.vfnet_reg(reg_feat_init)).float().exp() * reg_denom
elif self.bbox_norm_type == 'stride':
bbox_pred = scale(
self.vfnet_reg(reg_feat_init)).float().exp() * stride
else:
raise NotImplementedError
# compute star deformable convolution offsets
# converting dcn_offset to reg_feat.dtype thus VFNet can be
# trained with FP16
dcn_offset = self.star_dcn_offset(bbox_pred, self.gradient_mul,
stride).to(reg_feat.dtype)
# refine the bbox_pred
reg_feat = self.relu(self.vfnet_reg_refine_dconv(reg_feat, dcn_offset))
bbox_pred_refine = scale_refine(
self.vfnet_reg_refine(reg_feat)).float().exp()
bbox_pred_refine = bbox_pred_refine * bbox_pred.detach()
# predict the iou-aware cls score
cls_feat = self.relu(self.vfnet_cls_dconv(cls_feat, dcn_offset))
cls_score = self.vfnet_cls(cls_feat)
if self.training:
return cls_score, bbox_pred, bbox_pred_refine
else:
return cls_score, bbox_pred_refine
def star_dcn_offset(self, bbox_pred, gradient_mul, stride):
"""Compute the star deformable conv offsets.
Args:
bbox_pred (Tensor): Predicted bbox distance offsets (l, r, t, b).
gradient_mul (float): Gradient multiplier.
stride (int): The corresponding stride for feature maps,
used to project the bbox onto the feature map.
Returns:
dcn_offsets (Tensor): The offsets for deformable convolution.
"""
dcn_base_offset = self.dcn_base_offset.type_as(bbox_pred)
bbox_pred_grad_mul = (1 - gradient_mul) * bbox_pred.detach() + \
gradient_mul * bbox_pred
# map to the feature map scale
bbox_pred_grad_mul = bbox_pred_grad_mul / stride
N, C, H, W = bbox_pred.size()
x1 = bbox_pred_grad_mul[:, 0, :, :]
y1 = bbox_pred_grad_mul[:, 1, :, :]
x2 = bbox_pred_grad_mul[:, 2, :, :]
y2 = bbox_pred_grad_mul[:, 3, :, :]
bbox_pred_grad_mul_offset = bbox_pred.new_zeros(
N, 2 * self.num_dconv_points, H, W)
bbox_pred_grad_mul_offset[:, 0, :, :] = -1.0 * y1 # -y1
bbox_pred_grad_mul_offset[:, 1, :, :] = -1.0 * x1 # -x1
bbox_pred_grad_mul_offset[:, 2, :, :] = -1.0 * y1 # -y1
bbox_pred_grad_mul_offset[:, 4, :, :] = -1.0 * y1 # -y1
bbox_pred_grad_mul_offset[:, 5, :, :] = x2 # x2
bbox_pred_grad_mul_offset[:, 7, :, :] = -1.0 * x1 # -x1
bbox_pred_grad_mul_offset[:, 11, :, :] = x2 # x2
bbox_pred_grad_mul_offset[:, 12, :, :] = y2 # y2
bbox_pred_grad_mul_offset[:, 13, :, :] = -1.0 * x1 # -x1
bbox_pred_grad_mul_offset[:, 14, :, :] = y2 # y2
bbox_pred_grad_mul_offset[:, 16, :, :] = y2 # y2
bbox_pred_grad_mul_offset[:, 17, :, :] = x2 # x2
dcn_offset = bbox_pred_grad_mul_offset - dcn_base_offset
return dcn_offset
@force_fp32(apply_to=('cls_scores', 'bbox_preds', 'bbox_preds_refine'))
def loss(self,
cls_scores,
bbox_preds,
bbox_preds_refine,
gt_bboxes,
gt_labels,
img_metas,
gt_bboxes_ignore=None):
"""Compute loss of the head.
Args:
cls_scores (list[Tensor]): Box iou-aware scores for each scale
level, each is a 4D-tensor, the channel number is
num_points * num_classes.
bbox_preds (list[Tensor]): Box offsets for each
scale level, each is a 4D-tensor, the channel number is
num_points * 4.
bbox_preds_refine (list[Tensor]): Refined Box offsets for
each scale level, each is a 4D-tensor, the channel
number is num_points * 4.
gt_bboxes (list[Tensor]): Ground truth bboxes for each image with
shape (num_gts, 4) in [tl_x, tl_y, br_x, br_y] format.
gt_labels (list[Tensor]): class indices corresponding to each box
img_metas (list[dict]): Meta information of each image, e.g.,
image size, scaling factor, etc.
gt_bboxes_ignore (None | list[Tensor]): specify which bounding
boxes can be ignored when computing the loss.
Default: None.
Returns:
dict[str, Tensor]: A dictionary of loss components.
"""
assert len(cls_scores) == len(bbox_preds) == len(bbox_preds_refine)
featmap_sizes = [featmap.size()[-2:] for featmap in cls_scores]
all_level_points = self.fcos_prior_generator.grid_priors(
featmap_sizes, bbox_preds[0].dtype, bbox_preds[0].device)
labels, label_weights, bbox_targets, bbox_weights = self.get_targets(
cls_scores, all_level_points, gt_bboxes, gt_labels, img_metas,
gt_bboxes_ignore)
num_imgs = cls_scores[0].size(0)
# flatten cls_scores, bbox_preds and bbox_preds_refine
flatten_cls_scores = [
cls_score.permute(0, 2, 3,
1).reshape(-1,
self.cls_out_channels).contiguous()
for cls_score in cls_scores
]
flatten_bbox_preds = [
bbox_pred.permute(0, 2, 3, 1).reshape(-1, 4).contiguous()
for bbox_pred in bbox_preds
]
flatten_bbox_preds_refine = [
bbox_pred_refine.permute(0, 2, 3, 1).reshape(-1, 4).contiguous()
for bbox_pred_refine in bbox_preds_refine
]
flatten_cls_scores = torch.cat(flatten_cls_scores)
flatten_bbox_preds = torch.cat(flatten_bbox_preds)
flatten_bbox_preds_refine = torch.cat(flatten_bbox_preds_refine)
flatten_labels = torch.cat(labels)
flatten_bbox_targets = torch.cat(bbox_targets)
# repeat points to align with bbox_preds
flatten_points = torch.cat(
[points.repeat(num_imgs, 1) for points in all_level_points])
# FG cat_id: [0, num_classes - 1], BG cat_id: num_classes
bg_class_ind = self.num_classes
pos_inds = torch.where(
((flatten_labels >= 0) & (flatten_labels < bg_class_ind)) > 0)[0]
num_pos = len(pos_inds)
pos_bbox_preds = flatten_bbox_preds[pos_inds]
pos_bbox_preds_refine = flatten_bbox_preds_refine[pos_inds]
pos_labels = flatten_labels[pos_inds]
# sync num_pos across all gpus
if self.sync_num_pos:
num_pos_avg_per_gpu = reduce_mean(
pos_inds.new_tensor(num_pos).float()).item()
num_pos_avg_per_gpu = max(num_pos_avg_per_gpu, 1.0)
else:
num_pos_avg_per_gpu = num_pos
pos_bbox_targets = flatten_bbox_targets[pos_inds]
pos_points = flatten_points[pos_inds]
pos_decoded_bbox_preds = self.bbox_coder.decode(
pos_points, pos_bbox_preds)
pos_decoded_target_preds = self.bbox_coder.decode(
pos_points, pos_bbox_targets)
iou_targets_ini = bbox_overlaps(
pos_decoded_bbox_preds,
pos_decoded_target_preds.detach(),
is_aligned=True).clamp(min=1e-6)
bbox_weights_ini = iou_targets_ini.clone().detach()
bbox_avg_factor_ini = reduce_mean(
bbox_weights_ini.sum()).clamp_(min=1).item()
pos_decoded_bbox_preds_refine = \
self.bbox_coder.decode(pos_points, pos_bbox_preds_refine)
iou_targets_rf = bbox_overlaps(
pos_decoded_bbox_preds_refine,
pos_decoded_target_preds.detach(),
is_aligned=True).clamp(min=1e-6)
bbox_weights_rf = iou_targets_rf.clone().detach()
bbox_avg_factor_rf = reduce_mean(
bbox_weights_rf.sum()).clamp_(min=1).item()
if num_pos > 0:
loss_bbox = self.loss_bbox(
pos_decoded_bbox_preds,
pos_decoded_target_preds.detach(),
weight=bbox_weights_ini,
avg_factor=bbox_avg_factor_ini)
loss_bbox_refine = self.loss_bbox_refine(
pos_decoded_bbox_preds_refine,
pos_decoded_target_preds.detach(),
weight=bbox_weights_rf,
avg_factor=bbox_avg_factor_rf)
# build IoU-aware cls_score targets
if self.use_vfl:
pos_ious = iou_targets_rf.clone().detach()
cls_iou_targets = torch.zeros_like(flatten_cls_scores)
cls_iou_targets[pos_inds, pos_labels] = pos_ious
else:
loss_bbox = pos_bbox_preds.sum() * 0
loss_bbox_refine = pos_bbox_preds_refine.sum() * 0
if self.use_vfl:
cls_iou_targets = torch.zeros_like(flatten_cls_scores)
if self.use_vfl:
loss_cls = self.loss_cls(
flatten_cls_scores,
cls_iou_targets,
avg_factor=num_pos_avg_per_gpu)
else:
loss_cls = self.loss_cls(
flatten_cls_scores,
flatten_labels,
weight=label_weights,
avg_factor=num_pos_avg_per_gpu)
return dict(
loss_cls=loss_cls,
loss_bbox=loss_bbox,
loss_bbox_rf=loss_bbox_refine)
def get_targets(self, cls_scores, mlvl_points, gt_bboxes, gt_labels,
img_metas, gt_bboxes_ignore):
"""A wrapper for computing ATSS and FCOS targets for points in multiple
images.
Args:
cls_scores (list[Tensor]): Box iou-aware scores for each scale
level with shape (N, num_points * num_classes, H, W).
mlvl_points (list[Tensor]): Points of each fpn level, each has
shape (num_points, 2).
gt_bboxes (list[Tensor]): Ground truth bboxes of each image,
each has shape (num_gt, 4).
gt_labels (list[Tensor]): Ground truth labels of each box,
each has shape (num_gt,).
img_metas (list[dict]): Meta information of each image, e.g.,
image size, scaling factor, etc.
gt_bboxes_ignore (None | Tensor): Ground truth bboxes to be
ignored, shape (num_ignored_gts, 4).
Returns:
tuple:
labels_list (list[Tensor]): Labels of each level.
label_weights (Tensor/None): Label weights of all levels.
bbox_targets_list (list[Tensor]): Regression targets of each
level, (l, t, r, b).
bbox_weights (Tensor/None): Bbox weights of all levels.
"""
if self.use_atss:
return self.get_atss_targets(cls_scores, mlvl_points, gt_bboxes,
gt_labels, img_metas,
gt_bboxes_ignore)
else:
self.norm_on_bbox = False
return self.get_fcos_targets(mlvl_points, gt_bboxes, gt_labels)
def _get_target_single(self, *args, **kwargs):
"""Avoid ambiguity in multiple inheritance."""
if self.use_atss:
return ATSSHead._get_target_single(self, *args, **kwargs)
else:
return FCOSHead._get_target_single(self, *args, **kwargs)
def get_fcos_targets(self, points, gt_bboxes_list, gt_labels_list):
"""Compute FCOS regression and classification targets for points in
multiple images.
Args:
points (list[Tensor]): Points of each fpn level, each has shape
(num_points, 2).
gt_bboxes_list (list[Tensor]): Ground truth bboxes of each image,
each has shape (num_gt, 4).
gt_labels_list (list[Tensor]): Ground truth labels of each box,
each has shape (num_gt,).
Returns:
tuple:
labels (list[Tensor]): Labels of each level.
label_weights: None, to be compatible with ATSS targets.
bbox_targets (list[Tensor]): BBox targets of each level.
bbox_weights: None, to be compatible with ATSS targets.
"""
labels, bbox_targets = FCOSHead.get_targets(self, points,
gt_bboxes_list,
gt_labels_list)
label_weights = None
bbox_weights = None
return labels, label_weights, bbox_targets, bbox_weights
def get_anchors(self, featmap_sizes, img_metas, device='cuda'):
"""Get anchors according to feature map sizes.
Args:
featmap_sizes (list[tuple]): Multi-level feature map sizes.
img_metas (list[dict]): Image meta info.
device (torch.device | str): Device for returned tensors
Returns:
tuple:
anchor_list (list[Tensor]): Anchors of each image.
valid_flag_list (list[Tensor]): Valid flags of each image.
"""
num_imgs = len(img_metas)
# since feature map sizes of all images are the same, we only compute
# anchors for one time
multi_level_anchors = self.atss_prior_generator.grid_priors(
featmap_sizes, device=device)
anchor_list = [multi_level_anchors for _ in range(num_imgs)]
# for each image, we compute valid flags of multi level anchors
valid_flag_list = []
for img_id, img_meta in enumerate(img_metas):
multi_level_flags = self.atss_prior_generator.valid_flags(
featmap_sizes, img_meta['pad_shape'], device=device)
valid_flag_list.append(multi_level_flags)
return anchor_list, valid_flag_list
def get_atss_targets(self,
cls_scores,
mlvl_points,
gt_bboxes,
gt_labels,
img_metas,
gt_bboxes_ignore=None):
"""A wrapper for computing ATSS targets for points in multiple images.
Args:
cls_scores (list[Tensor]): Box iou-aware scores for each scale
level with shape (N, num_points * num_classes, H, W).
mlvl_points (list[Tensor]): Points of each fpn level, each has
shape (num_points, 2).
gt_bboxes (list[Tensor]): Ground truth bboxes of each image,
each has shape (num_gt, 4).
gt_labels (list[Tensor]): Ground truth labels of each box,
each has shape (num_gt,).
img_metas (list[dict]): Meta information of each image, e.g.,
image size, scaling factor, etc.
gt_bboxes_ignore (None | Tensor): Ground truth bboxes to be
ignored, shape (num_ignored_gts, 4). Default: None.
Returns:
tuple:
labels_list (list[Tensor]): Labels of each level.
label_weights (Tensor): Label weights of all levels.
bbox_targets_list (list[Tensor]): Regression targets of each
level, (l, t, r, b).
bbox_weights (Tensor): Bbox weights of all levels.
"""
featmap_sizes = [featmap.size()[-2:] for featmap in cls_scores]
assert len(
featmap_sizes
) == self.atss_prior_generator.num_levels == \
self.fcos_prior_generator.num_levels
device = cls_scores[0].device
anchor_list, valid_flag_list = self.get_anchors(
featmap_sizes, img_metas, device=device)
label_channels = self.cls_out_channels if self.use_sigmoid_cls else 1
cls_reg_targets = ATSSHead.get_targets(
self,
anchor_list,
valid_flag_list,
gt_bboxes,
img_metas,
gt_bboxes_ignore_list=gt_bboxes_ignore,
gt_labels_list=gt_labels,
label_channels=label_channels,
unmap_outputs=True)
if cls_reg_targets is None:
return None
(anchor_list, labels_list, label_weights_list, bbox_targets_list,
bbox_weights_list, num_total_pos, num_total_neg) = cls_reg_targets
bbox_targets_list = [
bbox_targets.reshape(-1, 4) for bbox_targets in bbox_targets_list
]
num_imgs = len(img_metas)
# transform bbox_targets (x1, y1, x2, y2) into (l, t, r, b) format
bbox_targets_list = self.transform_bbox_targets(
bbox_targets_list, mlvl_points, num_imgs)
labels_list = [labels.reshape(-1) for labels in labels_list]
label_weights_list = [
label_weights.reshape(-1) for label_weights in label_weights_list
]
bbox_weights_list = [
bbox_weights.reshape(-1) for bbox_weights in bbox_weights_list
]
label_weights = torch.cat(label_weights_list)
bbox_weights = torch.cat(bbox_weights_list)
return labels_list, label_weights, bbox_targets_list, bbox_weights
def transform_bbox_targets(self, decoded_bboxes, mlvl_points, num_imgs):
"""Transform bbox_targets (x1, y1, x2, y2) into (l, t, r, b) format.
Args:
decoded_bboxes (list[Tensor]): Regression targets of each level,
in the form of (x1, y1, x2, y2).
mlvl_points (list[Tensor]): Points of each fpn level, each has
shape (num_points, 2).
num_imgs (int): the number of images in a batch.
Returns:
bbox_targets (list[Tensor]): Regression targets of each level in
the form of (l, t, r, b).
"""
# TODO: Re-implemented in Class PointCoder
assert len(decoded_bboxes) == len(mlvl_points)
num_levels = len(decoded_bboxes)
mlvl_points = [points.repeat(num_imgs, 1) for points in mlvl_points]
bbox_targets = []
for i in range(num_levels):
bbox_target = self.bbox_coder.encode(mlvl_points[i],
decoded_bboxes[i])
bbox_targets.append(bbox_target)
return bbox_targets
def _load_from_state_dict(self, state_dict, prefix, local_metadata, strict,
missing_keys, unexpected_keys, error_msgs):
"""Override the method in the parent class to avoid changing para's
name."""
pass
def _get_points_single(self,
featmap_size,
stride,
dtype,
device,
flatten=False):
"""Get points according to feature map size.
This function will be deprecated soon.
"""
warnings.warn(
'`_get_points_single` in `VFNetHead` will be '
'deprecated soon, we support a multi level point generator now'
'you can get points of a single level feature map'
'with `self.fcos_prior_generator.single_level_grid_priors` ')
h, w = featmap_size
x_range = torch.arange(
0, w * stride, stride, dtype=dtype, device=device)
y_range = torch.arange(
0, h * stride, stride, dtype=dtype, device=device)
y, x = torch.meshgrid(y_range, x_range)
# to be compatible with anchor points in ATSS
if self.use_atss:
points = torch.stack(
(x.reshape(-1), y.reshape(-1)), dim=-1) + \
stride * self.anchor_center_offset
else:
points = torch.stack(
(x.reshape(-1), y.reshape(-1)), dim=-1) + stride // 2
return points