# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. from __future__ import absolute_import from __future__ import division from __future__ import print_function import math import paddle.fluid as fluid from paddle.fluid.param_attr import ParamAttr from paddle.fluid.initializer import Normal, Constant, NumpyArrayInitializer from paddle.fluid.regularizer import L2Decay from ppdet.modeling.ops import ConvNorm, DeformConvNorm from ppdet.modeling.ops import MultiClassNMS from ppdet.core.workspace import register __all__ = ['FCOSHead'] @register class FCOSHead(object): """ FCOSHead Args: num_classes (int): Number of classes fpn_stride (list): The stride of each FPN Layer prior_prob (float): Used to set the bias init for the class prediction layer num_convs (int): The layer number in fcos head norm_type (str): Normalization type, 'bn'/'sync_bn'/'affine_channel' fcos_loss (object): Instance of 'FCOSLoss' norm_reg_targets (bool): Normalization the regression target if true centerness_on_reg(bool): The prediction of centerness on regression or clssification branch use_dcn_in_tower (bool): Ues deformable conv on FCOSHead if true nms (object): Instance of 'MultiClassNMS' """ __inject__ = ['fcos_loss', 'nms'] __shared__ = ['num_classes'] def __init__(self, num_classes=81, fpn_stride=[8, 16, 32, 64, 128], prior_prob=0.01, num_convs=4, norm_type="gn", fcos_loss=None, norm_reg_targets=False, centerness_on_reg=False, use_dcn_in_tower=False, nms=MultiClassNMS( score_threshold=0.01, nms_top_k=1000, keep_top_k=100, nms_threshold=0.45, background_label=-1).__dict__): self.num_classes = num_classes - 1 self.fpn_stride = fpn_stride[::-1] self.prior_prob = prior_prob self.num_convs = num_convs self.norm_reg_targets = norm_reg_targets self.centerness_on_reg = centerness_on_reg self.use_dcn_in_tower = use_dcn_in_tower self.norm_type = norm_type self.fcos_loss = fcos_loss self.batch_size = 8 self.nms = nms if isinstance(nms, dict): self.nms = MultiClassNMS(**nms) def _fcos_head(self, features, fpn_stride, fpn_scale, is_training=False): """ Args: features (Variables): feature map from FPN fpn_stride (int): the stride of current feature map is_training (bool): whether is train or test mode """ subnet_blob_cls = features subnet_blob_reg = features in_channles = features.shape[1] if self.use_dcn_in_tower: conv_norm = DeformConvNorm else: conv_norm = ConvNorm for lvl in range(0, self.num_convs): conv_cls_name = 'fcos_head_cls_tower_conv_{}'.format(lvl) subnet_blob_cls = conv_norm( input=subnet_blob_cls, num_filters=in_channles, filter_size=3, stride=1, norm_type=self.norm_type, act='relu', initializer=Normal( loc=0., scale=0.01), bias_attr=True, norm_name=conv_cls_name + "_norm", name=conv_cls_name) conv_reg_name = 'fcos_head_reg_tower_conv_{}'.format(lvl) subnet_blob_reg = conv_norm( input=subnet_blob_reg, num_filters=in_channles, filter_size=3, stride=1, norm_type=self.norm_type, act='relu', initializer=Normal( loc=0., scale=0.01), bias_attr=True, norm_name=conv_reg_name + "_norm", name=conv_reg_name) conv_cls_name = "fcos_head_cls" bias_init_value = -math.log((1 - self.prior_prob) / self.prior_prob) cls_logits = fluid.layers.conv2d( input=subnet_blob_cls, num_filters=self.num_classes, filter_size=3, stride=1, padding=1, param_attr=ParamAttr( name=conv_cls_name + "_weights", initializer=Normal( loc=0., scale=0.01)), bias_attr=ParamAttr( name=conv_cls_name + "_bias", initializer=Constant(value=bias_init_value)), name=conv_cls_name) conv_reg_name = "fcos_head_reg" bbox_reg = fluid.layers.conv2d( input=subnet_blob_reg, num_filters=4, filter_size=3, stride=1, padding=1, param_attr=ParamAttr( name=conv_reg_name + "_weights", initializer=Normal( loc=0., scale=0.01)), bias_attr=ParamAttr( name=conv_reg_name + "_bias", initializer=Constant(value=0)), name=conv_reg_name) bbox_reg = bbox_reg * fpn_scale if self.norm_reg_targets: bbox_reg = fluid.layers.relu(bbox_reg) if not is_training: bbox_reg = bbox_reg * fpn_stride else: bbox_reg = fluid.layers.exp(bbox_reg) conv_centerness_name = "fcos_head_centerness" if self.centerness_on_reg: subnet_blob_ctn = subnet_blob_reg else: subnet_blob_ctn = subnet_blob_cls centerness = fluid.layers.conv2d( input=subnet_blob_ctn, num_filters=1, filter_size=3, stride=1, padding=1, param_attr=ParamAttr( name=conv_centerness_name + "_weights", initializer=Normal( loc=0., scale=0.01)), bias_attr=ParamAttr( name=conv_centerness_name + "_bias", initializer=Constant(value=0)), name=conv_centerness_name) return cls_logits, bbox_reg, centerness def _get_output(self, body_feats, is_training=False): """ Args: body_feates (list): the list of fpn feature maps is_training (bool): whether is train or test mode Return: cls_logits (Variables): prediction for classification bboxes_reg (Variables): prediction for bounding box centerness (Variables): prediction for ceterness """ cls_logits = [] bboxes_reg = [] centerness = [] assert len(body_feats) == len(self.fpn_stride), \ "The size of body_feats is not equal to size of fpn_stride" for fpn_name, fpn_stride in zip(body_feats, self.fpn_stride): features = body_feats[fpn_name] scale = fluid.layers.create_parameter( shape=[1, ], dtype="float32", name="%s_scale_on_reg" % fpn_name, default_initializer=fluid.initializer.Constant(1.)) cls_pred, bbox_pred, ctn_pred = self._fcos_head( features, fpn_stride, scale, is_training=is_training) cls_logits.append(cls_pred) bboxes_reg.append(bbox_pred) centerness.append(ctn_pred) return cls_logits, bboxes_reg, centerness def _compute_locations(self, features): """ Args: features (list): List of Variables for FPN feature maps Return: Anchor points for each feature map pixel """ locations = [] for lvl, fpn_name in enumerate(features): feature = features[fpn_name] shape_fm = fluid.layers.shape(feature) shape_fm.stop_gradient = True h = shape_fm[2] w = shape_fm[3] fpn_stride = self.fpn_stride[lvl] shift_x = fluid.layers.range( 0, w * fpn_stride, fpn_stride, dtype='float32') shift_y = fluid.layers.range( 0, h * fpn_stride, fpn_stride, dtype='float32') shift_x = fluid.layers.unsqueeze(shift_x, axes=[0]) shift_y = fluid.layers.unsqueeze(shift_y, axes=[1]) shift_x = fluid.layers.expand_as( shift_x, target_tensor=feature[0, 0, :, :]) shift_y = fluid.layers.expand_as( shift_y, target_tensor=feature[0, 0, :, :]) shift_x.stop_gradient = True shift_y.stop_gradient = True shift_x = fluid.layers.reshape(shift_x, shape=[-1]) shift_y = fluid.layers.reshape(shift_y, shape=[-1]) location = fluid.layers.stack( [shift_x, shift_y], axis=-1) + fpn_stride // 2 location.stop_gradient = True locations.append(location) return locations def __merge_hw(self, input, ch_type="channel_first"): """ Args: input (Variables): Feature map whose H and W will be merged into one dimension ch_type (str): channel_first / channel_last Return: new_shape (Variables): The new shape after h and w merged into one dimension """ shape_ = fluid.layers.shape(input) bs = shape_[0] ch = shape_[1] hi = shape_[2] wi = shape_[3] img_size = hi * wi img_size.stop_gradient = True if ch_type == "channel_first": new_shape = fluid.layers.concat([bs, ch, img_size]) elif ch_type == "channel_last": new_shape = fluid.layers.concat([bs, img_size, ch]) else: raise KeyError("Wrong ch_type %s" % ch_type) new_shape.stop_gradient = True return new_shape def _postprocessing_by_level(self, locations, box_cls, box_reg, box_ctn, im_info): """ Args: locations (Variables): anchor points for current layer box_cls (Variables): categories prediction box_reg (Variables): bounding box prediction box_ctn (Variables): centerness prediction im_info (Variables): [h, w, scale] for input images Return: box_cls_ch_last (Variables): score for each category, in [N, C, M] C is the number of classes and M is the number of anchor points box_reg_decoding (Variables): decoded bounding box, in [N, M, 4] last dimension is [x1, y1, x2, y2] """ act_shape_cls = self.__merge_hw(box_cls) box_cls_ch_last = fluid.layers.reshape( x=box_cls, shape=[self.batch_size, self.num_classes, -1], actual_shape=act_shape_cls) box_cls_ch_last = fluid.layers.sigmoid(box_cls_ch_last) act_shape_reg = self.__merge_hw(box_reg, "channel_last") box_reg_ch_last = fluid.layers.transpose(box_reg, perm=[0, 2, 3, 1]) box_reg_ch_last = fluid.layers.reshape( x=box_reg_ch_last, shape=[self.batch_size, -1, 4], actual_shape=act_shape_reg) act_shape_ctn = self.__merge_hw(box_ctn) box_ctn_ch_last = fluid.layers.reshape( x=box_ctn, shape=[self.batch_size, 1, -1], actual_shape=act_shape_ctn) box_ctn_ch_last = fluid.layers.sigmoid(box_ctn_ch_last) box_reg_decoding = fluid.layers.stack( [ locations[:, 0] - box_reg_ch_last[:, :, 0], locations[:, 1] - box_reg_ch_last[:, :, 1], locations[:, 0] + box_reg_ch_last[:, :, 2], locations[:, 1] + box_reg_ch_last[:, :, 3] ], axis=1) box_reg_decoding = fluid.layers.transpose( box_reg_decoding, perm=[0, 2, 1]) # recover the location to original image im_scale = im_info[:, 2] box_reg_decoding = box_reg_decoding / im_scale box_cls_ch_last = box_cls_ch_last * box_ctn_ch_last return box_cls_ch_last, box_reg_decoding def _post_processing(self, locations, cls_logits, bboxes_reg, centerness, im_info): """ Args: locations (list): List of Variables composed by center of each anchor point cls_logits (list): List of Variables for class prediction bboxes_reg (list): List of Variables for bounding box prediction centerness (list): List of Variables for centerness prediction im_info(Variables): [h, w, scale] for input images Return: pred (LoDTensor): predicted bounding box after nms, the shape is n x 6, last dimension is [label, score, xmin, ymin, xmax, ymax] """ pred_boxes_ = [] pred_scores_ = [] for _, ( pts, cls, box, ctn ) in enumerate(zip(locations, cls_logits, bboxes_reg, centerness)): pred_scores_lvl, pred_boxes_lvl = self._postprocessing_by_level( pts, cls, box, ctn, im_info) pred_boxes_.append(pred_boxes_lvl) pred_scores_.append(pred_scores_lvl) pred_boxes = fluid.layers.concat(pred_boxes_, axis=1) pred_scores = fluid.layers.concat(pred_scores_, axis=2) pred = self.nms(pred_boxes, pred_scores) return pred def get_loss(self, input, tag_labels, tag_bboxes, tag_centerness): """ Calculate the loss for FCOS Args: input (list): List of Variables for feature maps from FPN layers tag_labels (Variables): category targets for each anchor point tag_bboxes (Variables): bounding boxes targets for positive samples tag_centerness (Variables): centerness targets for positive samples Return: loss (dict): loss composed by classification loss, bounding box regression loss and centerness regression loss """ cls_logits, bboxes_reg, centerness = self._get_output( input, is_training=True) loss = self.fcos_loss(cls_logits, bboxes_reg, centerness, tag_labels, tag_bboxes, tag_centerness) return loss def get_prediction(self, input, im_info): """ Decode the prediction Args: input (list): List of Variables for feature maps from FPN layers im_info(Variables): [h, w, scale] for input images Return: the bounding box prediction """ cls_logits, bboxes_reg, centerness = self._get_output( input, is_training=False) locations = self._compute_locations(input) pred = self._post_processing(locations, cls_logits, bboxes_reg, centerness, im_info) return {"bbox": pred}