# 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 from paddle import fluid from paddle.fluid.param_attr import ParamAttr from ppdet.core.workspace import register, serializable INF = 1e8 __all__ = ['FCOSLoss'] @register @serializable class FCOSLoss(object): """ FCOSLoss Args: loss_alpha (float): alpha in focal loss loss_gamma (float): gamma in focal loss iou_loss_type(str): location loss type, IoU/GIoU/LINEAR_IoU reg_weights(float): weight for location loss """ def __init__(self, loss_alpha=0.25, loss_gamma=2.0, iou_loss_type="IoU", reg_weights=1.0): self.loss_alpha = loss_alpha self.loss_gamma = loss_gamma self.iou_loss_type = iou_loss_type self.reg_weights = reg_weights def __flatten_tensor(self, input, channel_first=False): """ Flatten a Tensor Args: input (Variables): Input Tensor channel_first(bool): if true the dimension order of Tensor is [N, C, H, W], otherwise is [N, H, W, C] Return: input_channel_last (Variables): The flattened Tensor in channel_last style """ if channel_first: input_channel_last = fluid.layers.transpose( input, perm=[0, 2, 3, 1]) else: input_channel_last = input input_channel_last = fluid.layers.flatten(input_channel_last, axis=3) return input_channel_last def __iou_loss(self, pred, targets, positive_mask, weights=None): """ Calculate the loss for location prediction Args: pred (Variables): bounding boxes prediction targets (Variables): targets for positive samples positive_mask (Variables): mask of positive samples weights (Variables): weights for each positive samples Return: loss (Varialbes): location loss """ plw = fluid.layers.elementwise_mul(pred[:, 0], positive_mask, axis=0) pth = fluid.layers.elementwise_mul(pred[:, 1], positive_mask, axis=0) prw = fluid.layers.elementwise_mul(pred[:, 2], positive_mask, axis=0) pbh = fluid.layers.elementwise_mul(pred[:, 3], positive_mask, axis=0) tlw = fluid.layers.elementwise_mul(targets[:, 0], positive_mask, axis=0) tth = fluid.layers.elementwise_mul(targets[:, 1], positive_mask, axis=0) trw = fluid.layers.elementwise_mul(targets[:, 2], positive_mask, axis=0) tbh = fluid.layers.elementwise_mul(targets[:, 3], positive_mask, axis=0) tlw.stop_gradient = True trw.stop_gradient = True tth.stop_gradient = True tbh.stop_gradient = True area_target = (tlw + trw) * (tth + tbh) area_predict = (plw + prw) * (pth + pbh) ilw = fluid.layers.elementwise_min(plw, tlw) irw = fluid.layers.elementwise_min(prw, trw) ith = fluid.layers.elementwise_min(pth, tth) ibh = fluid.layers.elementwise_min(pbh, tbh) clw = fluid.layers.elementwise_max(plw, tlw) crw = fluid.layers.elementwise_max(prw, trw) cth = fluid.layers.elementwise_max(pth, tth) cbh = fluid.layers.elementwise_max(pbh, tbh) area_inter = (ilw + irw) * (ith + ibh) ious = (area_inter + 1.0) / ( area_predict + area_target - area_inter + 1.0) ious = fluid.layers.elementwise_mul(ious, positive_mask, axis=0) if self.iou_loss_type.lower() == "linear_iou": loss = 1.0 - ious elif self.iou_loss_type.lower() == "giou": area_uniou = area_predict + area_target - area_inter area_circum = (clw + crw) * (cth + cbh) + 1e-7 giou = ious - (area_circum - area_uniou) / area_circum loss = 1.0 - giou elif self.iou_loss_type.lower() == "iou": loss = 0.0 - fluid.layers.log(ious) else: raise KeyError if weights is not None: loss = loss * weights return loss def __call__(self, cls_logits, bboxes_reg, centerness, tag_labels, tag_bboxes, tag_center): """ Calculate the loss for classification, location and centerness Args: cls_logits (list): list of Variables, which is predicted score for all anchor points with shape [N, M, C] bboxes_reg (list): list of Variables, which is predicted offsets for all anchor points with shape [N, M, 4] centerness (list): list of Variables, which is predicted centerness for all anchor points with shape [N, M, 1] tag_labels (list): list of Variables, which is category targets for each anchor point tag_bboxes (list): list of Variables, which is bounding boxes targets for positive samples tag_center (list): list of Variables, which is centerness targets for positive samples Return: loss (dict): loss composed by classification loss, bounding box """ cls_logits_flatten_list = [] bboxes_reg_flatten_list = [] centerness_flatten_list = [] tag_labels_flatten_list = [] tag_bboxes_flatten_list = [] tag_center_flatten_list = [] num_lvl = len(cls_logits) for lvl in range(num_lvl): cls_logits_flatten_list.append( self.__flatten_tensor(cls_logits[num_lvl - 1 - lvl], True)) bboxes_reg_flatten_list.append( self.__flatten_tensor(bboxes_reg[num_lvl - 1 - lvl], True)) centerness_flatten_list.append( self.__flatten_tensor(centerness[num_lvl - 1 - lvl], True)) tag_labels_flatten_list.append( self.__flatten_tensor(tag_labels[lvl], False)) tag_bboxes_flatten_list.append( self.__flatten_tensor(tag_bboxes[lvl], False)) tag_center_flatten_list.append( self.__flatten_tensor(tag_center[lvl], False)) cls_logits_flatten = fluid.layers.concat( cls_logits_flatten_list, axis=0) bboxes_reg_flatten = fluid.layers.concat( bboxes_reg_flatten_list, axis=0) centerness_flatten = fluid.layers.concat( centerness_flatten_list, axis=0) tag_labels_flatten = fluid.layers.concat( tag_labels_flatten_list, axis=0) tag_bboxes_flatten = fluid.layers.concat( tag_bboxes_flatten_list, axis=0) tag_center_flatten = fluid.layers.concat( tag_center_flatten_list, axis=0) tag_labels_flatten.stop_gradient = True tag_bboxes_flatten.stop_gradient = True tag_center_flatten.stop_gradient = True mask_positive = tag_labels_flatten > 0 mask_positive.stop_gradient = True mask_positive_float = fluid.layers.cast(mask_positive, dtype="float32") mask_positive_float.stop_gradient = True num_positive_fp32 = fluid.layers.reduce_sum(mask_positive_float) num_positive_int32 = fluid.layers.cast(num_positive_fp32, dtype="int32") num_positive_int32 = num_positive_int32 * 0 + 1 num_positive_fp32.stop_gradient = True num_positive_int32.stop_gradient = True normalize_sum = fluid.layers.sum(tag_center_flatten) normalize_sum.stop_gradient = True normalize_sum = fluid.layers.reduce_sum(mask_positive_float * normalize_sum) normalize_sum.stop_gradient = True cls_loss = fluid.layers.sigmoid_focal_loss( cls_logits_flatten, tag_labels_flatten, num_positive_int32) / num_positive_fp32 reg_loss = self.__iou_loss(bboxes_reg_flatten, tag_bboxes_flatten, mask_positive_float, tag_center_flatten) reg_loss = fluid.layers.elementwise_mul( reg_loss, mask_positive_float, axis=0) / normalize_sum ctn_loss = fluid.layers.sigmoid_cross_entropy_with_logits( x=centerness_flatten, label=tag_center_flatten) ctn_loss = fluid.layers.elementwise_mul( ctn_loss, mask_positive_float, axis=0) / num_positive_fp32 loss_all = { "loss_centerness": fluid.layers.reduce_sum(ctn_loss), "loss_cls": fluid.layers.reduce_sum(cls_loss), "loss_box": fluid.layers.reduce_sum(reg_loss) } return loss_all