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| # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved. | |
| import torch | |
| from maskrcnn_benchmark.modeling.box_coder import BoxCoder | |
| from maskrcnn_benchmark.structures.bounding_box import BoxList | |
| from maskrcnn_benchmark.structures.boxlist_ops import cat_boxlist | |
| from maskrcnn_benchmark.structures.boxlist_ops import boxlist_nms | |
| from maskrcnn_benchmark.structures.boxlist_ops import remove_small_boxes | |
| from ..utils import cat | |
| from .utils import permute_and_flatten | |
| class RPNPostProcessor(torch.nn.Module): | |
| """ | |
| Performs post-processing on the outputs of the RPN boxes, before feeding the | |
| proposals to the heads | |
| """ | |
| def __init__( | |
| self, | |
| pre_nms_top_n, | |
| post_nms_top_n, | |
| nms_thresh, | |
| min_size, | |
| box_coder=None, | |
| fpn_post_nms_top_n=None, | |
| ): | |
| """ | |
| Arguments: | |
| pre_nms_top_n (int) | |
| post_nms_top_n (int) | |
| nms_thresh (float) | |
| min_size (int) | |
| box_coder (BoxCoder) | |
| fpn_post_nms_top_n (int) | |
| """ | |
| super(RPNPostProcessor, self).__init__() | |
| self.pre_nms_top_n = pre_nms_top_n # 12000 | |
| self.post_nms_top_n = post_nms_top_n # 2000 | |
| self.nms_thresh = nms_thresh # 0.7 | |
| self.min_size = min_size # 0 | |
| if box_coder is None: | |
| box_coder = BoxCoder(weights=(1.0, 1.0, 1.0, 1.0)) | |
| self.box_coder = box_coder | |
| if fpn_post_nms_top_n is None: | |
| fpn_post_nms_top_n = post_nms_top_n | |
| self.fpn_post_nms_top_n = fpn_post_nms_top_n # 2000 | |
| def add_gt_proposals(self, proposals, targets): | |
| """ | |
| Arguments: | |
| proposals: list[BoxList] | |
| targets: list[BoxList] | |
| """ | |
| # Get the device we're operating on | |
| device = proposals[0].bbox.device | |
| gt_boxes = [target.copy_with_fields([]) for target in targets] | |
| # later cat of bbox requires all fields to be present for all bbox | |
| # so we need to add a dummy for objectness that's missing | |
| for gt_box in gt_boxes: | |
| gt_box.add_field("objectness", torch.ones(len(gt_box), device=device)) | |
| proposals = [ | |
| cat_boxlist((proposal, gt_box)) | |
| for proposal, gt_box in zip(proposals, gt_boxes) | |
| ] | |
| return proposals | |
| def forward_for_single_feature_map(self, anchors, objectness, box_regression): | |
| """ | |
| Arguments: | |
| anchors: list[BoxList] # [image,number,[n,4]] | |
| objectness: tensor of size N, A, H, W | |
| box_regression: tensor of size N, A * 4, H, W | |
| """ | |
| device = objectness.device | |
| N, A, H, W = objectness.shape | |
| # put in the same format as anchors | |
| objectness = permute_and_flatten(objectness, N, A, 1, H, W).view(N, -1) # N H*W*A*1 | |
| objectness = objectness.sigmoid() | |
| box_regression = permute_and_flatten(box_regression, N, A, 18, H, W) # N H*W*A 4 | |
| num_anchors = A * H * W # 391040 97760 | |
| pre_nms_top_n = min(self.pre_nms_top_n, num_anchors) #12000 | |
| objectness, topk_idx = objectness.topk(pre_nms_top_n, dim=1, sorted=True) | |
| # objectness = objectness.cpu() | |
| batch_idx = torch.arange(N, device=device)[:, None] | |
| box_regression = box_regression[batch_idx, topk_idx] | |
| image_shapes = [box.size for box in anchors] | |
| concat_anchors = torch.cat([a.bbox for a in anchors], dim=0) | |
| concat_anchors = concat_anchors.reshape(N, -1, 4)[batch_idx, topk_idx] | |
| proposals = self.box_coder.decode_iou( | |
| box_regression.view(-1, 18), concat_anchors.view(-1, 4) | |
| ) | |
| proposals = proposals.view(N, -1, 4) | |
| result = [] | |
| for proposal, score, im_shape in zip(proposals, objectness, image_shapes): | |
| boxlist = BoxList(proposal, im_shape, mode="xyxy") | |
| boxlist.add_field("objectness", score) | |
| boxlist = boxlist.clip_to_image(remove_empty=False) | |
| boxlist = remove_small_boxes(boxlist, self.min_size) | |
| boxlist = boxlist_nms( | |
| boxlist, | |
| self.nms_thresh, | |
| max_proposals=self.post_nms_top_n, | |
| score_field="objectness", | |
| ) | |
| result.append(boxlist) | |
| return result | |
| def forward(self, anchors, objectness, box_regression, targets=None): | |
| """ | |
| Arguments: | |
| anchors: list[list[BoxList]] | |
| objectness: list[tensor] | |
| box_regression: list[tensor] | |
| Returns: | |
| boxlists (list[BoxList]): the post-processed anchors, after | |
| applying box decoding and NMS | |
| """ | |
| sampled_boxes = [] | |
| num_levels = len(objectness) # classification | |
| anchors = list(zip(*anchors)) # [image,number,[n,4]] | |
| # i =-1 | |
| for a, o, b in zip(anchors, objectness, box_regression): | |
| sampled_boxes.append(self.forward_for_single_feature_map(a, o, b)) | |
| boxlists = list(zip(*sampled_boxes)) | |
| boxlists = [cat_boxlist(boxlist) for boxlist in boxlists] | |
| if num_levels > 1: | |
| boxlists = self.select_over_all_levels(boxlists) | |
| # append ground-truth bboxes to proposals | |
| if self.training and targets is not None: | |
| boxlists = self.add_gt_proposals(boxlists, targets) | |
| return boxlists | |
| def select_over_all_levels(self, boxlists): | |
| num_images = len(boxlists) | |
| # different behavior during training and during testing: | |
| # during training, post_nms_top_n is over *all* the proposals combined, while | |
| # during testing, it is over the proposals for each image | |
| # TODO resolve this difference and make it consistent. It should be per image, | |
| # and not per batch | |
| if self.training: | |
| objectness = torch.cat( | |
| [boxlist.get_field("objectness") for boxlist in boxlists], dim=0 | |
| ) | |
| box_sizes = [len(boxlist) for boxlist in boxlists] | |
| post_nms_top_n = min(self.fpn_post_nms_top_n, len(objectness)) | |
| _, inds_sorted = torch.topk(objectness, post_nms_top_n, dim=0, sorted=True) | |
| inds_mask = torch.zeros_like(objectness, dtype=torch.uint8) | |
| inds_mask[inds_sorted] = 1 | |
| inds_mask = inds_mask.split(box_sizes) | |
| for i in range(num_images): | |
| boxlists[i] = boxlists[i][inds_mask[i]] | |
| else: | |
| for i in range(num_images): | |
| objectness = boxlists[i].get_field("objectness") | |
| post_nms_top_n = min(self.fpn_post_nms_top_n, len(objectness)) | |
| _, inds_sorted = torch.topk( | |
| objectness, post_nms_top_n, dim=0, sorted=True | |
| ) | |
| boxlists[i] = boxlists[i][inds_sorted] | |
| return boxlists | |
| def make_rpn_postprocessor(config, rpn_box_coder, is_train): | |
| fpn_post_nms_top_n = config.MODEL.RPN.FPN_POST_NMS_TOP_N_TRAIN # 2000 | |
| if not is_train: | |
| fpn_post_nms_top_n = config.MODEL.RPN.FPN_POST_NMS_TOP_N_TEST | |
| pre_nms_top_n = config.MODEL.RPN.PRE_NMS_TOP_N_TRAIN # 12000 | |
| post_nms_top_n = config.MODEL.RPN.POST_NMS_TOP_N_TRAIN # 2000 | |
| if not is_train: | |
| pre_nms_top_n = config.MODEL.RPN.PRE_NMS_TOP_N_TEST | |
| post_nms_top_n = config.MODEL.RPN.POST_NMS_TOP_N_TEST | |
| nms_thresh = config.MODEL.RPN.NMS_THRESH # 0.7 | |
| min_size = config.MODEL.RPN.MIN_SIZE # 0 | |
| box_selector = RPNPostProcessor( | |
| pre_nms_top_n=pre_nms_top_n, #12000 | |
| post_nms_top_n=post_nms_top_n, #2000 | |
| nms_thresh=nms_thresh, # 0.7 | |
| min_size=min_size, # 0 | |
| box_coder=rpn_box_coder, | |
| fpn_post_nms_top_n=fpn_post_nms_top_n, #2000 | |
| ) | |
| return box_selector | |