Exemple #1
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    def forward(self, locations, box_cls, box_regression, centerness, proposal_embed, proposal_margin, pixel_embed, image_sizes, targets):
        """
        Arguments:
            anchors: list[list[BoxList]]
            box_cls: list[tensor]
            box_regression: list[tensor]
            image_sizes: list[(h, w)]
        Returns:
            boxlists (list[BoxList]): the post-processed anchors, after
                applying box decoding and NMS
        """
        sampled_boxes = []
        for i, (l, o, b, c) in enumerate(zip(locations, box_cls, box_regression, centerness)):
            em = proposal_embed[i]
            mar = proposal_margin[i]
            if self.fix_margin:
                mar = torch.ones_like(mar) * self.init_margin
            sampled_boxes.append(
                self.forward_for_single_feature_map(
                    l, o, b, c, em, mar, image_sizes, i
                )
            )
        boxlists = list(zip(*sampled_boxes))
        boxlists = [cat_boxlist(boxlist) for boxlist in boxlists]
        boxlists = self.select_over_all_levels(boxlists)

        # resize pixel embedding for higher resolution
        N, dim, m_h, m_w = pixel_embed.shape
        o_h = m_h * self.mask_scale_factor
        o_w = m_w * self.mask_scale_factor
        pixel_embed = interpolate(pixel_embed, size=(o_h, o_w), mode='bilinear', align_corners=False)

        boxlists = self.forward_for_mask(boxlists, pixel_embed)

        return boxlists
Exemple #2
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    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)
        anchors = list(zip(*anchors))
        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
Exemple #3
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    def forward(self, locations, box_cls, box_regression, centerness, box_mask,
                image_sizes):
        """
        Arguments:
            anchors: list[list[BoxList]]
            box_cls: list[tensor]
            box_regression: list[tensor]
            box_mask: list[tensor]
            image_sizes: list[(h, w)]
        Returns:
            boxlists (list[BoxList]): the post-processed anchors, after
                applying box decoding and NMS
        """
        sampled_boxes = []
        for _, (l, o, b, c, m) in enumerate(
                zip(locations, box_cls, box_regression, centerness, box_mask)):
            sampled_boxes.append(
                self.forward_for_single_feature_map(l, o, b, c, m,
                                                    image_sizes))

        boxlists = list(zip(*sampled_boxes))
        boxlists = [cat_boxlist(boxlist) for boxlist in boxlists]
        boxlists = self.select_over_all_levels(boxlists)

        return boxlists
Exemple #4
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    def forward(self, locations, box_cls, box_regression, centerness, image_sizes, benchmark=False, timers=None):
        """
        Arguments:
            anchors: list[list[BoxList]]
            box_cls: list[tensor]
            box_regression: list[tensor]
            image_sizes: list[(h, w)]
        Returns:
            boxlists (list[BoxList]): the post-processed anchors, after
                applying box decoding and NMS
        """
        if benchmark and timers is not None:
            torch.cuda.synchronize()
            timers[2].tic()
        sampled_boxes = []
        for _, (l, o, b, c) in enumerate(zip(locations, box_cls, box_regression, centerness)):
            sampled_boxes.append(
                self.forward_for_single_feature_map(
                    l, o, b, c, image_sizes
                )
            )
        if benchmark and timers is not None:
            torch.cuda.synchronize()
            timers[2].toc()
            timers[3].tic()

        boxlists = list(zip(*sampled_boxes))
        boxlists = [cat_boxlist(boxlist) for boxlist in boxlists]
        if not self.bbox_aug_enabled:
            boxlists = self.select_over_all_levels(boxlists)
        if benchmark and timers is not None:
            torch.cuda.synchronize()
            timers[3].toc()

        return boxlists
Exemple #5
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    def select_over_all_levels(self, boxlists):
        num_images = len(boxlists)
        results = []
        for i in range(num_images):
            scores = boxlists[i].get_field("scores")
            labels = boxlists[i].get_field("labels")
            diagonals = boxlists[i].get_field("diagonals")
            boxes = boxlists[i].bbox
            boxlist = boxlists[i]
            result = []
            # skip the background
            for j in tqdm(range(1, self.num_classes)):
                inds = (labels == j).nonzero().view(-1)

                scores_j = scores[inds]
                boxes_j = boxes[inds, :].view(-1, 4)
                diagonals_j = diagonals[inds, :].view(-1, 16)
                boxlist_for_class = BoxList(boxes_j, boxlist.size, mode="xyxy")
                boxlist_for_class.add_field("scores", scores_j)
                boxlist_for_class.add_field("diagonals", diagonals_j)
                if scores_j.size()[0] != 0:
                    boxlist_for_class = diagonal_nms(boxlist_for_class,
                                                     self.nms_thresh,
                                                     self.nms_topk,
                                                     score_field="scores")
                    num_labels = len(boxlist_for_class)
                    boxlist_for_class.add_field(
                        "labels",
                        torch.full((num_labels, ),
                                   j,
                                   dtype=torch.int64,
                                   device=scores.device))
                    result.append(boxlist_for_class)

            result = cat_boxlist(result)
            # new_result = all_class_nms(result, self.nms_thresh)
            number_of_detections = len(result)
            print('Number of detections in this image {}'.format(
                number_of_detections))

            # Limit to max_per_image detections **over all classes**
            if number_of_detections > self.fpn_post_nms_top_n > 0:
                cls_scores = result.get_field("scores")
                image_thresh, _ = torch.kthvalue(
                    cls_scores.cpu(),
                    number_of_detections - self.fpn_post_nms_top_n + 1)
                # image_thresh = torch.as_tensor(0.5)
                keep = cls_scores >= image_thresh.item()
                keep = torch.nonzero(keep).squeeze(1)
                result = result[keep]
            result = all_class_nms(result, self.nms_thresh)
            results.append(result)

        return results
Exemple #6
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def cat_boxlist_with_keypoints(boxlists):
    assert all(boxlist.has_field("keypoints") for boxlist in boxlists)

    kp = [boxlist.get_field("keypoints").keypoints for boxlist in boxlists]
    kp = cat(kp, 0)

    fields = boxlists[0].get_fields()
    fields = [field for field in fields if field != "keypoints"]

    boxlists = [boxlist.copy_with_fields(fields) for boxlist in boxlists]
    boxlists = cat_boxlist(boxlists)
    boxlists.add_field("keypoints", kp)
    return boxlists
Exemple #7
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    def __call__(self, box_regression, centerness, targets, anchors):
        labels, reg_targets = self.prepare_targets(targets, anchors)

        N = len(labels)
        box_regression_flatten = self.concat_box_prediction_layers(
            box_regression)
        centerness_flatten = [
            ct.permute(0, 2, 3, 1).reshape(N, -1, 1) for ct in centerness
        ]
        centerness_flatten = torch.cat(centerness_flatten, dim=1).reshape(-1)

        labels_flatten = torch.cat(labels, dim=0)
        reg_targets_flatten = torch.cat(reg_targets, dim=0)
        anchors_flatten = torch.cat([
            cat_boxlist(anchors_per_image).bbox
            for anchors_per_image in anchors
        ],
                                    dim=0)

        pos_inds = torch.nonzero(labels_flatten > 0).squeeze(1)

        num_gpus = get_num_gpus()
        total_num_pos = reduce_sum(pos_inds.new_tensor([pos_inds.numel()
                                                        ])).item()
        num_pos_avg_per_gpu = max(total_num_pos / float(num_gpus), 1.0)

        box_regression_flatten = box_regression_flatten[pos_inds]
        reg_targets_flatten = reg_targets_flatten[pos_inds]
        anchors_flatten = anchors_flatten[pos_inds]
        centerness_flatten = centerness_flatten[pos_inds]
        centerness_targets = self.compute_centerness_targets(
            reg_targets_flatten, anchors_flatten)
        sum_centerness_targets_avg_per_gpu = reduce_sum(
            centerness_targets.sum()).item() / float(num_gpus)

        if pos_inds.numel() > 0:
            reg_loss = self.GIoULoss(
                box_regression_flatten,
                reg_targets_flatten,
                anchors_flatten,
                weight=centerness_targets) / sum_centerness_targets_avg_per_gpu
            centerness_loss = self.centerness_loss_func(
                centerness_flatten, centerness_targets) / num_pos_avg_per_gpu
        else:
            reg_loss = box_regression_flatten.sum()
            centerness_loss = centerness_flatten.sum()

        return reg_loss * self.cfg.MODEL.ATSS.REG_LOSS_WEIGHT, centerness_loss
Exemple #8
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    def select_over_all_levels(self, boxlists):
        num_images = len(boxlists)
        results = []
        for i in range(num_images):
            scores = boxlists[i].get_field("scores")
            labels = boxlists[i].get_field("labels")
            masks = boxlists[i].get_field("mask")
            boxes = boxlists[i].bbox
            boxlist = boxlists[i]
            result = []

            # skip the background
            for j in range(1, self.num_classes):
                inds = (labels == j).nonzero().view(-1)

                scores_j = scores[inds]
                boxes_j = boxes[inds, :].view(-1, 4)
                boxlist_for_class = BoxList(boxes_j, boxlist.size, mode="xyxy")
                boxlist_for_class.add_field("scores", scores_j)
                boxlist_for_class, keep = boxlist_nms_with_keep(
                    boxlist_for_class, self.nms_thresh, score_field="scores")
                num_labels = len(boxlist_for_class)

                boxlist_for_class.add_field(
                    "labels",
                    torch.full((num_labels, ),
                               j,
                               dtype=torch.int64,
                               device=scores.device))
                boxlist_for_class.add_field("mask", masks[inds[keep], :, :, :])
                result.append(boxlist_for_class)

            result = cat_boxlist(result)
            number_of_detections = len(result)

            # Limit to max_per_image detections **over all classes**
            if number_of_detections > self.fpn_post_nms_top_n > 0:
                cls_scores = result.get_field("scores")
                image_thresh, _ = torch.kthvalue(
                    cls_scores.cpu(),
                    number_of_detections - self.fpn_post_nms_top_n + 1)
                keep = cls_scores >= image_thresh.item()
                keep = torch.nonzero(keep).squeeze(1)
                result = result[keep]
            results.append(result)
        return results
Exemple #9
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    def __call__(self, anchors, objectness, box_regression, targets):
        """
        Arguments:
            anchors (list[BoxList])
            objectness (list[Tensor])
            box_regression (list[Tensor])
            targets (list[BoxList])

        Returns:
            objectness_loss (Tensor)
            box_loss (Tensor
        """
        anchors = [
            cat_boxlist(anchors_per_image) for anchors_per_image in anchors
        ]
        labels, regression_targets = self.prepare_targets(anchors, targets)
        sampled_pos_inds, sampled_neg_inds = self.fg_bg_sampler(labels)
        sampled_pos_inds = torch.nonzero(torch.cat(sampled_pos_inds,
                                                   dim=0)).squeeze(1)
        sampled_neg_inds = torch.nonzero(torch.cat(sampled_neg_inds,
                                                   dim=0)).squeeze(1)

        sampled_inds = torch.cat([sampled_pos_inds, sampled_neg_inds], dim=0)

        objectness, box_regression = \
                concat_box_prediction_layers(objectness, box_regression)

        objectness = objectness.squeeze()

        labels = torch.cat(labels, dim=0)
        regression_targets = torch.cat(regression_targets, dim=0)

        box_loss = smooth_l1_loss(
            box_regression[sampled_pos_inds],
            regression_targets[sampled_pos_inds],
            beta=1.0 / 9,
            size_average=False,
        ) / (sampled_inds.numel())
        # box_loss = self.box_reg_loss_func(box_regression[sampled_pos_inds],
        #                                   regression_targets[sampled_pos_inds]) / (sampled_inds.numel())

        objectness_loss = F.binary_cross_entropy_with_logits(
            objectness[sampled_inds], labels[sampled_inds])

        return objectness_loss, box_loss
def merge_result_from_multi_scales(boxlists, nms_type='nms', vote_thresh=0.65):
    num_images = len(boxlists)
    results = []
    for i in range(num_images):
        scores = boxlists[i].get_field("scores")
        labels = boxlists[i].get_field("labels")
        boxes = boxlists[i].bbox
        boxlist = boxlists[i]
        result = []
        # skip the background
        for j in range(1, cfg.MODEL.RETINANET.NUM_CLASSES):
            inds = (labels == j).nonzero().view(-1)

            scores_j = scores[inds]
            boxes_j = boxes[inds, :].view(-1, 4)
            boxlist_for_class = BoxList(boxes_j, boxlist.size, mode="xyxy")
            boxlist_for_class.add_field("scores", scores_j)
            boxlist_for_class = boxlist_nms(boxlist_for_class,
                                            cfg.MODEL.ATSS.NMS_TH,
                                            score_field="scores",
                                            nms_type=nms_type,
                                            vote_thresh=vote_thresh)
            num_labels = len(boxlist_for_class)
            boxlist_for_class.add_field(
                "labels",
                torch.full((num_labels, ),
                           j,
                           dtype=torch.int64,
                           device=scores.device))
            result.append(boxlist_for_class)

        result = cat_boxlist(result)
        number_of_detections = len(result)

        # Limit to max_per_image detections **over all classes**
        if number_of_detections > cfg.MODEL.ATSS.PRE_NMS_TOP_N > 0:
            cls_scores = result.get_field("scores")
            image_thresh, _ = torch.kthvalue(
                cls_scores.cpu(),
                number_of_detections - cfg.MODEL.ATSS.PRE_NMS_TOP_N + 1)
            keep = cls_scores >= image_thresh.item()
            keep = torch.nonzero(keep).squeeze(1)
            result = result[keep]
        results.append(result)
    return results
    def filter_results(self, boxlist, num_classes):
        """Returns bounding-box detection results by thresholding on scores and
        applying non-maximum suppression (NMS).
        """
        # unwrap the boxlist to avoid additional overhead.
        # if we had multi-class NMS, we could perform this directly on the boxlist
        boxes = boxlist.bbox.reshape(-1, num_classes * 4)
        scores = boxlist.get_field("scores").reshape(-1, num_classes)

        device = scores.device
        result = []
        # Apply threshold on detection probabilities and apply NMS
        # Skip j = 0, because it's the background class
        inds_all = scores > self.score_thresh
        for j in range(1, num_classes):
            inds = inds_all[:, j].nonzero().squeeze(1)
            scores_j = scores[inds, j]
            boxes_j = boxes[inds, j * 4:(j + 1) * 4]
            boxlist_for_class = BoxList(boxes_j, boxlist.size, mode="xyxy")
            boxlist_for_class.add_field("scores", scores_j)
            boxlist_for_class = boxlist_nms(boxlist_for_class, self.nms)
            num_labels = len(boxlist_for_class)
            boxlist_for_class.add_field(
                "labels",
                torch.full((num_labels, ), j, dtype=torch.int64,
                           device=device))
            result.append(boxlist_for_class)

        result = cat_boxlist(result)
        number_of_detections = len(result)

        # Limit to max_per_image detections **over all classes**
        if number_of_detections > self.detections_per_img > 0:
            cls_scores = result.get_field("scores")
            image_thresh, _ = torch.kthvalue(
                cls_scores.cpu(),
                number_of_detections - self.detections_per_img + 1)
            keep = cls_scores >= image_thresh.item()
            keep = torch.nonzero(keep).squeeze(1)
            result = result[keep]
        return result
Exemple #12
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    def __call__(self, anchors, box_cls, box_regression, targets):
        """
        Arguments:
            anchors (list[BoxList])
            box_cls (list[Tensor])
            box_regression (list[Tensor])
            targets (list[BoxList])

        Returns:
            retinanet_cls_loss (Tensor)
            retinanet_regression_loss (Tensor
        """
        anchors = [
            cat_boxlist(anchors_per_image) for anchors_per_image in anchors
        ]
        labels, regression_targets = self.prepare_targets(anchors, targets)

        N = len(labels)
        box_cls, box_regression = \
                concat_box_prediction_layers(box_cls, box_regression)

        labels = torch.cat(labels, dim=0)
        regression_targets = torch.cat(regression_targets, dim=0)
        pos_inds = torch.nonzero(labels > 0).squeeze(1)

        retinanet_regression_loss = smooth_l1_loss(
            box_regression[pos_inds],
            regression_targets[pos_inds],
            beta=self.bbox_reg_beta,
            size_average=False,
        ) / (max(1,
                 pos_inds.numel() * self.regress_norm))

        labels = labels.int()

        retinanet_cls_loss = self.box_cls_loss_func(
            box_cls, labels) / (pos_inds.numel() + N)

        return retinanet_cls_loss, retinanet_regression_loss
Exemple #13
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    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
Exemple #14
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    def __call__(self, anchors, objectness, box_regression, targets):
        """
        Arguments:
            anchors (list[BoxList])
            objectness (list[Tensor])
            box_regression (list[Tensor])
            targets (list[BoxList])

        Returns:
            objectness_loss (Tensor)
            box_loss (Tensor
        """
        print_log = (self.num_call % 100) == 0
        self.num_call += 1
        if print_log:
            all_anchor_sizes_each_pyramid = [[len(a) for a in anchors_per_image]
                for anchors_per_image in anchors]
        anchor_boxes = [cat_boxlist(anchors_per_image) for anchors_per_image in anchors]
        all_num_anchor_per_level = [[len(a) for a in anchors_per_image] for anchors_per_image in anchors]
        labels, regression_targets = self.prepare_targets(
            anchor_boxes, targets, all_num_anchor_per_level)

        if print_log:
            with torch.no_grad():
                all_kind_to_num = get_kind_to_num_info(labels, all_anchor_sizes_each_pyramid)
                for kind_to_num in all_kind_to_num:
                    for k in kind_to_num:
                        kind_to_num[k] /= 1. * len(targets)
                from qd.qd_common import print_table
                print_table(all_kind_to_num)
                #if self.all_kind_to_num is None:
                    #self.all_kind_to_num = all_kind_to_num
                #else:
                    #for kind_to_num, self_kind_to_num in zip(all_kind_to_num, self.all_kind_to_num):
                        #for kind, num in kind_to_num.items():
                            #self_kind_to_num[kind] += num
                #print_table(self.all_kind_to_num)

        sampled_pos_inds, sampled_neg_inds = self.fg_bg_sampler(labels)
        sampled_pos_inds = torch.nonzero(torch.cat(sampled_pos_inds, dim=0),
                                         as_tuple=False).squeeze(1)
        sampled_neg_inds = torch.nonzero(torch.cat(sampled_neg_inds, dim=0),
                                         as_tuple=False).squeeze(1)

        sampled_inds = torch.cat([sampled_pos_inds, sampled_neg_inds], dim=0)

        objectness, box_regression = \
                concat_box_prediction_layers(objectness, box_regression)

        objectness = objectness.squeeze()

        labels = torch.cat(labels, dim=0)
        regression_targets = torch.cat(regression_targets, dim=0)

        box_loss = smooth_l1_loss(
            box_regression[sampled_pos_inds],
            regression_targets[sampled_pos_inds],
            beta=1.0 / 9,
            size_average=False,
        ) / (sampled_inds.numel())

        objectness_loss = F.binary_cross_entropy_with_logits(
            objectness[sampled_inds], labels[sampled_inds]
        )

        return objectness_loss, box_loss
Exemple #15
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    def prepare_targets(self, targets, anchors):
        cls_labels = []
        reg_targets = []
        for im_i in range(len(targets)):
            targets_per_im = targets[im_i]
            assert targets_per_im.mode == "xyxy"
            bboxes_per_im = targets_per_im.bbox
            labels_per_im = targets_per_im.get_field("labels")
            anchors_per_im = cat_boxlist(anchors[im_i])
            num_gt = bboxes_per_im.shape[0]

            if self.cfg.MODEL.ATSS.POSITIVE_TYPE == 'SSC':
                object_sizes_of_interest = [[-1, 64], [64, 128], [128, 256], [256, 512], [512, INF]]
                area_per_im = targets_per_im.area()
                expanded_object_sizes_of_interest = []
                points = []
                for l, anchors_per_level in enumerate(anchors[im_i]):
                    anchors_per_level = anchors_per_level.bbox
                    anchors_cx_per_level = (anchors_per_level[:, 2] + anchors_per_level[:, 0]) / 2.0
                    anchors_cy_per_level = (anchors_per_level[:, 3] + anchors_per_level[:, 1]) / 2.0
                    points_per_level = torch.stack((anchors_cx_per_level, anchors_cy_per_level), dim=1)
                    points.append(points_per_level)
                    object_sizes_of_interest_per_level = \
                        points_per_level.new_tensor(object_sizes_of_interest[l])
                    expanded_object_sizes_of_interest.append(
                        object_sizes_of_interest_per_level[None].expand(len(points_per_level), -1)
                    )
                expanded_object_sizes_of_interest = torch.cat(expanded_object_sizes_of_interest, dim=0)
                points = torch.cat(points, dim=0)

                xs, ys = points[:, 0], points[:, 1]
                l = xs[:, None] - bboxes_per_im[:, 0][None]
                t = ys[:, None] - bboxes_per_im[:, 1][None]
                r = bboxes_per_im[:, 2][None] - xs[:, None]
                b = bboxes_per_im[:, 3][None] - ys[:, None]
                reg_targets_per_im = torch.stack([l, t, r, b], dim=2)

                is_in_boxes = reg_targets_per_im.min(dim=2)[0] > 0.01

                max_reg_targets_per_im = reg_targets_per_im.max(dim=2)[0]
                is_cared_in_the_level = \
                    (max_reg_targets_per_im >= expanded_object_sizes_of_interest[:, [0]]) & \
                    (max_reg_targets_per_im <= expanded_object_sizes_of_interest[:, [1]])

                locations_to_gt_area = area_per_im[None].repeat(len(points), 1)
                locations_to_gt_area[is_in_boxes == 0] = INF
                locations_to_gt_area[is_cared_in_the_level == 0] = INF
                locations_to_min_area, locations_to_gt_inds = locations_to_gt_area.min(dim=1)

                cls_labels_per_im = labels_per_im[locations_to_gt_inds]
                cls_labels_per_im[locations_to_min_area == INF] = 0
                matched_gts = bboxes_per_im[locations_to_gt_inds]
            elif self.cfg.MODEL.ATSS.POSITIVE_TYPE == 'ATSS':
                num_anchors_per_loc = len(self.cfg.MODEL.ATSS.ASPECT_RATIOS) * self.cfg.MODEL.ATSS.SCALES_PER_OCTAVE

                num_anchors_per_level = [len(anchors_per_level.bbox) for anchors_per_level in anchors[im_i]]
                ious = boxlist_iou(anchors_per_im, targets_per_im)

                gt_cx = (bboxes_per_im[:, 2] + bboxes_per_im[:, 0]) / 2.0
                gt_cy = (bboxes_per_im[:, 3] + bboxes_per_im[:, 1]) / 2.0
                gt_points = torch.stack((gt_cx, gt_cy), dim=1)

                anchors_cx_per_im = (anchors_per_im.bbox[:, 2] + anchors_per_im.bbox[:, 0]) / 2.0
                anchors_cy_per_im = (anchors_per_im.bbox[:, 3] + anchors_per_im.bbox[:, 1]) / 2.0
                anchor_points = torch.stack((anchors_cx_per_im, anchors_cy_per_im), dim=1)

                distances = (anchor_points[:, None, :] - gt_points[None, :, :]).pow(2).sum(-1).sqrt()

                # Selecting candidates based on the center distance between anchor box and object
                candidate_idxs = []
                star_idx = 0
                for level, anchors_per_level in enumerate(anchors[im_i]):
                    end_idx = star_idx + num_anchors_per_level[level]
                    distances_per_level = distances[star_idx:end_idx, :]
                    topk = min(self.cfg.MODEL.ATSS.TOPK * num_anchors_per_loc, num_anchors_per_level[level])
                    _, topk_idxs_per_level = distances_per_level.topk(topk, dim=0, largest=False)
                    candidate_idxs.append(topk_idxs_per_level + star_idx)
                    star_idx = end_idx
                candidate_idxs = torch.cat(candidate_idxs, dim=0)

                # Using the sum of mean and standard deviation as the IoU threshold to select final positive samples
                candidate_ious = ious[candidate_idxs, torch.arange(num_gt)]
                iou_mean_per_gt = candidate_ious.mean(0)
                iou_std_per_gt = candidate_ious.std(0)
                iou_thresh_per_gt = iou_mean_per_gt + iou_std_per_gt
                is_pos = candidate_ious >= iou_thresh_per_gt[None, :]

                # Limiting the final positive samples’ center to object
                anchor_num = anchors_cx_per_im.shape[0]
                for ng in range(num_gt):
                    candidate_idxs[:, ng] += ng * anchor_num
                e_anchors_cx = anchors_cx_per_im.view(1, -1).expand(num_gt, anchor_num).contiguous().view(-1)
                e_anchors_cy = anchors_cy_per_im.view(1, -1).expand(num_gt, anchor_num).contiguous().view(-1)
                candidate_idxs = candidate_idxs.view(-1)
                l = e_anchors_cx[candidate_idxs].view(-1, num_gt) - bboxes_per_im[:, 0]
                t = e_anchors_cy[candidate_idxs].view(-1, num_gt) - bboxes_per_im[:, 1]
                r = bboxes_per_im[:, 2] - e_anchors_cx[candidate_idxs].view(-1, num_gt)
                b = bboxes_per_im[:, 3] - e_anchors_cy[candidate_idxs].view(-1, num_gt)
                is_in_gts = torch.stack([l, t, r, b], dim=1).min(dim=1)[0] > 0.01
                is_pos = is_pos & is_in_gts

                # if an anchor box is assigned to multiple gts, the one with the highest IoU will be selected.
                ious_inf = torch.full_like(ious, -INF).t().contiguous().view(-1)
                index = candidate_idxs.view(-1)[is_pos.view(-1)]
                ious_inf[index] = ious.t().contiguous().view(-1)[index]
                ious_inf = ious_inf.view(num_gt, -1).t()

                anchors_to_gt_values, anchors_to_gt_indexs = ious_inf.max(dim=1)
                cls_labels_per_im = labels_per_im[anchors_to_gt_indexs]
                cls_labels_per_im[anchors_to_gt_values == -INF] = 0
                matched_gts = bboxes_per_im[anchors_to_gt_indexs]
            elif self.cfg.MODEL.ATSS.POSITIVE_TYPE == 'TOPK':
                gt_cx = (bboxes_per_im[:, 2] + bboxes_per_im[:, 0]) / 2.0
                gt_cy = (bboxes_per_im[:, 3] + bboxes_per_im[:, 1]) / 2.0
                gt_points = torch.stack((gt_cx, gt_cy), dim=1)

                anchors_cx_per_im = (anchors_per_im.bbox[:, 2] + anchors_per_im.bbox[:, 0]) / 2.0
                anchors_cy_per_im = (anchors_per_im.bbox[:, 3] + anchors_per_im.bbox[:, 1]) / 2.0
                anchor_points = torch.stack((anchors_cx_per_im, anchors_cy_per_im), dim=1)

                distances = (anchor_points[:, None, :] - gt_points[None, :, :]).pow(2).sum(-1).sqrt()
                distances = distances / distances.max() / 1000
                ious = boxlist_iou(anchors_per_im, targets_per_im)

                is_pos = ious * False
                for ng in range(num_gt):
                    _, topk_idxs = (ious[:, ng] - distances[:, ng]).topk(self.cfg.MODEL.ATSS.TOPK, dim=0)
                    l = anchors_cx_per_im[topk_idxs] - bboxes_per_im[ng, 0]
                    t = anchors_cy_per_im[topk_idxs] - bboxes_per_im[ng, 1]
                    r = bboxes_per_im[ng, 2] - anchors_cx_per_im[topk_idxs]
                    b = bboxes_per_im[ng, 3] - anchors_cy_per_im[topk_idxs]
                    is_in_gt = torch.stack([l, t, r, b], dim=1).min(dim=1)[0] > 0.01
                    is_pos[topk_idxs[is_in_gt == 1], ng] = True

                ious[is_pos == 0] = -INF
                anchors_to_gt_values, anchors_to_gt_indexs = ious.max(dim=1)

                cls_labels_per_im = labels_per_im[anchors_to_gt_indexs]
                cls_labels_per_im[anchors_to_gt_values == -INF] = 0
                matched_gts = bboxes_per_im[anchors_to_gt_indexs]
            elif self.cfg.MODEL.ATSS.POSITIVE_TYPE == 'IoU':
                match_quality_matrix = boxlist_iou(targets_per_im, anchors_per_im)
                matched_idxs = self.matcher(match_quality_matrix)
                targets_per_im = targets_per_im.copy_with_fields(['labels'])
                matched_targets = targets_per_im[matched_idxs.clamp(min=0)]

                cls_labels_per_im = matched_targets.get_field("labels")
                cls_labels_per_im = cls_labels_per_im.to(dtype=torch.float32)

                # Background (negative examples)
                bg_indices = matched_idxs == Matcher.BELOW_LOW_THRESHOLD
                cls_labels_per_im[bg_indices] = 0

                # discard indices that are between thresholds
                inds_to_discard = matched_idxs == Matcher.BETWEEN_THRESHOLDS
                cls_labels_per_im[inds_to_discard] = -1

                matched_gts = matched_targets.bbox

                # Limiting positive samples’ center to object
                # in order to filter out poor positives and use the centerness branch
                pos_idxs = torch.nonzero(cls_labels_per_im > 0).squeeze(1)
                pos_anchors_cx = (anchors_per_im.bbox[pos_idxs, 2] + anchors_per_im.bbox[pos_idxs, 0]) / 2.0
                pos_anchors_cy = (anchors_per_im.bbox[pos_idxs, 3] + anchors_per_im.bbox[pos_idxs, 1]) / 2.0
                l = pos_anchors_cx - matched_gts[pos_idxs, 0]
                t = pos_anchors_cy - matched_gts[pos_idxs, 1]
                r = matched_gts[pos_idxs, 2] - pos_anchors_cx
                b = matched_gts[pos_idxs, 3] - pos_anchors_cy
                is_in_gts = torch.stack([l, t, r, b], dim=1).min(dim=1)[0] > 0.01
                cls_labels_per_im[pos_idxs[is_in_gts == 0]] = -1
            else:
                raise NotImplementedError

            reg_targets_per_im = self.box_coder.encode(matched_gts, anchors_per_im.bbox)
            cls_labels.append(cls_labels_per_im)
            reg_targets.append(reg_targets_per_im)

        return cls_labels, reg_targets