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@@ -0,0 +1,419 @@
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+import numpy as np
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+import torch
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+import torch.nn as nn
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+import torch.nn.functional as F
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+from utils.box_ops import bbox_iou
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+
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+
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+# -------------------------- YOLOv5 Assigner --------------------------
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+class Yolov5Matcher(object):
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+ def __init__(self, num_classes, num_anchors, anchor_size, anchor_theshold):
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+ self.num_classes = num_classes
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+ self.num_anchors = num_anchors
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+ self.anchor_theshold = anchor_theshold
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+ # [KA, 2]
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+ self.anchor_sizes = np.array([[anchor[0], anchor[1]]
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+ for anchor in anchor_size])
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+ # [KA, 4]
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+ self.anchor_boxes = np.array([[0., 0., anchor[0], anchor[1]]
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+ for anchor in anchor_size])
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+
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+ def compute_iou(self, anchor_boxes, gt_box):
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+ """
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+ anchor_boxes : ndarray -> [KA, 4] (cx, cy, bw, bh).
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+ gt_box : ndarray -> [1, 4] (cx, cy, bw, bh).
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+ """
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+ # anchors: [KA, 4]
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+ anchors = np.zeros_like(anchor_boxes)
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+ anchors[..., :2] = anchor_boxes[..., :2] - anchor_boxes[..., 2:] * 0.5 # x1y1
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+ anchors[..., 2:] = anchor_boxes[..., :2] + anchor_boxes[..., 2:] * 0.5 # x2y2
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+ anchors_area = anchor_boxes[..., 2] * anchor_boxes[..., 3]
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+
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+ # gt_box: [1, 4] -> [KA, 4]
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+ gt_box = np.array(gt_box).reshape(-1, 4)
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+ gt_box = np.repeat(gt_box, anchors.shape[0], axis=0)
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+ gt_box_ = np.zeros_like(gt_box)
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+ gt_box_[..., :2] = gt_box[..., :2] - gt_box[..., 2:] * 0.5 # x1y1
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+ gt_box_[..., 2:] = gt_box[..., :2] + gt_box[..., 2:] * 0.5 # x2y2
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+ gt_box_area = np.prod(gt_box[..., 2:] - gt_box[..., :2], axis=1)
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+
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+ # intersection
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+ inter_w = np.minimum(anchors[:, 2], gt_box_[:, 2]) - \
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+ np.maximum(anchors[:, 0], gt_box_[:, 0])
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+ inter_h = np.minimum(anchors[:, 3], gt_box_[:, 3]) - \
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+ np.maximum(anchors[:, 1], gt_box_[:, 1])
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+ inter_area = inter_w * inter_h
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+
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+ # union
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+ union_area = anchors_area + gt_box_area - inter_area
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+
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+ # iou
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+ iou = inter_area / union_area
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+ iou = np.clip(iou, a_min=1e-10, a_max=1.0)
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+
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+ return iou
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+
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+
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+ def iou_assignment(self, ctr_points, gt_box, fpn_strides):
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+ # compute IoU
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+ iou = self.compute_iou(self.anchor_boxes, gt_box)
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+ iou_mask = (iou > 0.5)
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+
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+ label_assignment_results = []
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+ if iou_mask.sum() == 0:
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+ # We assign the anchor box with highest IoU score.
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+ iou_ind = np.argmax(iou)
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+
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+ level = iou_ind // self.num_anchors # pyramid level
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+ anchor_idx = iou_ind - level * self.num_anchors # anchor index
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+
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+ # get the corresponding stride
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+ stride = fpn_strides[level]
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+
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+ # compute the grid cell
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+ xc, yc = ctr_points
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+ xc_s = xc / stride
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+ yc_s = yc / stride
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+ grid_x = int(xc_s)
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+ grid_y = int(yc_s)
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+
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+ label_assignment_results.append([grid_x, grid_y, xc_s, yc_s, level, anchor_idx])
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+ else:
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+ for iou_ind, iou_m in enumerate(iou_mask):
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+ if iou_m:
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+ level = iou_ind // self.num_anchors # pyramid level
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+ anchor_idx = iou_ind - level * self.num_anchors # anchor index
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+
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+ # get the corresponding stride
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+ stride = fpn_strides[level]
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+
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+ # compute the gride cell
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+ xc, yc = ctr_points
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+ xc_s = xc / stride
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+ yc_s = yc / stride
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+ grid_x = int(xc_s)
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+ grid_y = int(yc_s)
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+
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+ label_assignment_results.append([grid_x, grid_y, xc_s, yc_s, level, anchor_idx])
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+
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+ return label_assignment_results
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+
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+
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+ def aspect_ratio_assignment(self, ctr_points, keeps, fpn_strides):
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+ label_assignment_results = []
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+ for keep_idx, keep in enumerate(keeps):
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+ if keep:
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+ level = keep_idx // self.num_anchors # pyramid level
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+ anchor_idx = keep_idx - level * self.num_anchors # anchor index
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+
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+ # get the corresponding stride
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+ stride = fpn_strides[level]
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+
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+ # compute the gride cell
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+ xc, yc = ctr_points
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+ xc_s = xc / stride
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+ yc_s = yc / stride
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+ grid_x = int(xc_s)
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+ grid_y = int(yc_s)
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+
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+ label_assignment_results.append([grid_x, grid_y, xc_s, yc_s, level, anchor_idx])
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+
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+ return label_assignment_results
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+
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+
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+ @torch.no_grad()
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+ def __call__(self, fmp_sizes, fpn_strides, targets):
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+ """
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+ fmp_size: (List) [fmp_h, fmp_w]
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+ fpn_strides: (List) -> [8, 16, 32, ...] stride of network output.
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+ targets: (Dict) dict{'boxes': [...],
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+ 'labels': [...],
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+ 'orig_size': ...}
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+ """
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+ assert len(fmp_sizes) == len(fpn_strides)
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+ # prepare
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+ bs = len(targets)
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+ gt_objectness = [
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+ torch.zeros([bs, fmp_h, fmp_w, self.num_anchors, 1])
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+ for (fmp_h, fmp_w) in fmp_sizes
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+ ]
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+ gt_classes = [
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+ torch.zeros([bs, fmp_h, fmp_w, self.num_anchors, self.num_classes])
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+ for (fmp_h, fmp_w) in fmp_sizes
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+ ]
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+ gt_bboxes = [
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+ torch.zeros([bs, fmp_h, fmp_w, self.num_anchors, 4])
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+ for (fmp_h, fmp_w) in fmp_sizes
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+ ]
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+
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+ for batch_index in range(bs):
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+ targets_per_image = targets[batch_index]
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+ # [N,]
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+ tgt_cls = targets_per_image["labels"].numpy()
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+ # [N, 4]
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+ tgt_box = targets_per_image['boxes'].numpy()
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+
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+ for gt_box, gt_label in zip(tgt_box, tgt_cls):
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+ # get a bbox coords
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+ x1, y1, x2, y2 = gt_box.tolist()
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+ # xyxy -> cxcywh
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+ xc, yc = (x2 + x1) * 0.5, (y2 + y1) * 0.5
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+ bw, bh = x2 - x1, y2 - y1
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+ gt_box = np.array([[0., 0., bw, bh]])
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+
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+ # check target
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+ if bw < 1. or bh < 1.:
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+ # invalid target
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+ continue
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+
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+ # compute aspect ratio
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+ ratios = gt_box[..., 2:] / self.anchor_sizes
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+ keeps = np.maximum(ratios, 1 / ratios).max(-1) < self.anchor_theshold
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+
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+ if keeps.sum() == 0:
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+ label_assignment_results = self.iou_assignment([xc, yc], gt_box, fpn_strides)
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+ else:
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+ label_assignment_results = self.aspect_ratio_assignment([xc, yc], keeps, fpn_strides)
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+
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+ # label assignment
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+ for result in label_assignment_results:
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+ # assignment
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+ grid_x, grid_y, xc_s, yc_s, level, anchor_idx = result
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+ stride = fpn_strides[level]
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+ fmp_h, fmp_w = fmp_sizes[level]
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+ # coord on the feature
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+ x1s, y1s = x1 / stride, y1 / stride
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+ x2s, y2s = x2 / stride, y2 / stride
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+ # offset
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+ off_x = xc_s - grid_x
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+ off_y = yc_s - grid_y
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+
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+ if off_x <= 0.5 and off_y <= 0.5: # top left
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+ grids = [(grid_x-1, grid_y), (grid_x, grid_y-1), (grid_x, grid_y)]
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+ elif off_x > 0.5 and off_y <= 0.5: # top right
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+ grids = [(grid_x+1, grid_y), (grid_x, grid_y-1), (grid_x, grid_y)]
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+ elif off_x <= 0.5 and off_y > 0.5: # bottom left
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+ grids = [(grid_x-1, grid_y), (grid_x, grid_y+1), (grid_x, grid_y)]
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+ elif off_x > 0.5 and off_y > 0.5: # bottom right
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+ grids = [(grid_x+1, grid_y), (grid_x, grid_y+1), (grid_x, grid_y)]
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+
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+ for (i, j) in grids:
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+ is_in_box = (j >= y1s and j < y2s) and (i >= x1s and i < x2s)
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+ is_valid = (j >= 0 and j < fmp_h) and (i >= 0 and i < fmp_w)
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+
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+ if is_in_box and is_valid:
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+ # obj
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+ gt_objectness[level][batch_index, j, i, anchor_idx] = 1.0
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+ # cls
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+ cls_ont_hot = torch.zeros(self.num_classes)
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+ cls_ont_hot[int(gt_label)] = 1.0
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+ gt_classes[level][batch_index, j, i, anchor_idx] = cls_ont_hot
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+ # box
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+ gt_bboxes[level][batch_index, j, i, anchor_idx] = torch.as_tensor([x1, y1, x2, y2])
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+
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+ # [B, M, C]
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+ gt_objectness = torch.cat([gt.view(bs, -1, 1) for gt in gt_objectness], dim=1).float()
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+ gt_classes = torch.cat([gt.view(bs, -1, self.num_classes) for gt in gt_classes], dim=1).float()
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+ gt_bboxes = torch.cat([gt.view(bs, -1, 4) for gt in gt_bboxes], dim=1).float()
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+
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+ return gt_objectness, gt_classes, gt_bboxes
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+
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+
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+# -------------------------- Task Aligned Assigner --------------------------
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+class TaskAlignedAssigner(nn.Module):
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+ def __init__(self,
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+ topk=10,
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+ num_classes=80,
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+ alpha=0.5,
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+ beta=6.0,
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+ eps=1e-9):
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+ super(TaskAlignedAssigner, self).__init__()
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+ self.topk = topk
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+ self.num_classes = num_classes
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+ self.bg_idx = num_classes
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+ self.alpha = alpha
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+ self.beta = beta
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+ self.eps = eps
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+
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+ @torch.no_grad()
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+ def forward(self,
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+ pd_scores,
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+ pd_bboxes,
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+ anc_points,
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+ gt_labels,
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+ gt_bboxes):
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+ """This code referenced to
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+ https://github.com/Nioolek/PPYOLOE_pytorch/blob/master/ppyoloe/assigner/tal_assigner.py
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+ Args:
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+ pd_scores (Tensor): shape(bs, num_total_anchors, num_classes)
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+ pd_bboxes (Tensor): shape(bs, num_total_anchors, 4)
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+ anc_points (Tensor): shape(num_total_anchors, 2)
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+ gt_labels (Tensor): shape(bs, n_max_boxes, 1)
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+ gt_bboxes (Tensor): shape(bs, n_max_boxes, 4)
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+ Returns:
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+ target_labels (Tensor): shape(bs, num_total_anchors)
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+ target_bboxes (Tensor): shape(bs, num_total_anchors, 4)
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+ target_scores (Tensor): shape(bs, num_total_anchors, num_classes)
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+ fg_mask (Tensor): shape(bs, num_total_anchors)
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+ """
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+ self.bs = pd_scores.size(0)
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+ self.n_max_boxes = gt_bboxes.size(1)
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+
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+ mask_pos, align_metric, overlaps = self.get_pos_mask(
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+ pd_scores, pd_bboxes, gt_labels, gt_bboxes, anc_points)
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+
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+ target_gt_idx, fg_mask, mask_pos = select_highest_overlaps(
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+ mask_pos, overlaps, self.n_max_boxes)
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+
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+ # assigned target
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+ target_labels, target_bboxes, target_scores = self.get_targets(
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+ gt_labels, gt_bboxes, target_gt_idx, fg_mask)
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+
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+ # normalize
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+ align_metric *= mask_pos
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+ pos_align_metrics = align_metric.amax(axis=-1, keepdim=True) # b, max_num_obj
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+ pos_overlaps = (overlaps * mask_pos).amax(axis=-1, keepdim=True) # b, max_num_obj
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+ norm_align_metric = (align_metric * pos_overlaps / (pos_align_metrics + self.eps)).amax(-2).unsqueeze(-1)
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+ target_scores = target_scores * norm_align_metric
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+
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+ return target_labels, target_bboxes, target_scores, fg_mask.bool(), target_gt_idx
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+
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+
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+ def get_pos_mask(self, pd_scores, pd_bboxes, gt_labels, gt_bboxes, anc_points):
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+ # get anchor_align metric, (b, max_num_obj, h*w)
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+ align_metric, overlaps = self.get_box_metrics(pd_scores, pd_bboxes, gt_labels, gt_bboxes)
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+ # get in_gts mask, (b, max_num_obj, h*w)
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+ mask_in_gts = select_candidates_in_gts(anc_points, gt_bboxes)
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+ # get topk_metric mask, (b, max_num_obj, h*w)
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+ mask_topk = self.select_topk_candidates(align_metric * mask_in_gts)
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+ # merge all mask to a final mask, (b, max_num_obj, h*w)
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+ mask_pos = mask_topk * mask_in_gts
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+
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+ return mask_pos, align_metric, overlaps
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+
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+
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+ def get_box_metrics(self, pd_scores, pd_bboxes, gt_labels, gt_bboxes):
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+ ind = torch.zeros([2, self.bs, self.n_max_boxes], dtype=torch.long) # 2, b, max_num_obj
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+ ind[0] = torch.arange(end=self.bs).view(-1, 1).repeat(1, self.n_max_boxes) # b, max_num_obj
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+ ind[1] = gt_labels.long().squeeze(-1) # b, max_num_obj
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+ # get the scores of each grid for each gt cls
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+ bbox_scores = pd_scores[ind[0], :, ind[1]] # b, max_num_obj, h*w
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+
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+ overlaps = bbox_iou(gt_bboxes.unsqueeze(2), pd_bboxes.unsqueeze(1), xywh=False,
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+ CIoU=True).squeeze(3).clamp(0)
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+ align_metric = bbox_scores.pow(self.alpha) * overlaps.pow(self.beta)
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+
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+ return align_metric, overlaps
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+
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+
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+ def select_topk_candidates(self, metrics, largest=True):
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+ """
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+ Args:
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+ metrics: (b, max_num_obj, h*w).
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+ topk_mask: (b, max_num_obj, topk) or None
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+ """
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+
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+ num_anchors = metrics.shape[-1] # h*w
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+ # (b, max_num_obj, topk)
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+ topk_metrics, topk_idxs = torch.topk(metrics, self.topk, dim=-1, largest=largest)
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+ topk_mask = (topk_metrics.max(-1, keepdim=True)[0] > self.eps).tile([1, 1, self.topk])
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+ # (b, max_num_obj, topk)
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+ topk_idxs[~topk_mask] = 0
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+ # (b, max_num_obj, topk, h*w) -> (b, max_num_obj, h*w)
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+ is_in_topk = F.one_hot(topk_idxs, num_anchors).sum(-2)
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+ # filter invalid bboxes
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+ is_in_topk = torch.where(is_in_topk > 1, 0, is_in_topk)
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+ return is_in_topk.to(metrics.dtype)
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+
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+
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+ def get_targets(self, gt_labels, gt_bboxes, target_gt_idx, fg_mask):
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+ """
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+ Args:
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+ gt_labels: (b, max_num_obj, 1)
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+ gt_bboxes: (b, max_num_obj, 4)
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+ target_gt_idx: (b, h*w)
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+ fg_mask: (b, h*w)
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|
|
+ """
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|
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+
|
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+ # assigned target labels, (b, 1)
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|
|
+ batch_ind = torch.arange(end=self.bs, dtype=torch.int64, device=gt_labels.device)[..., None]
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+ target_gt_idx = target_gt_idx + batch_ind * self.n_max_boxes # (b, h*w)
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|
|
+ target_labels = gt_labels.long().flatten()[target_gt_idx] # (b, h*w)
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|
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+
|
|
|
+ # assigned target boxes, (b, max_num_obj, 4) -> (b, h*w)
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|
+ target_bboxes = gt_bboxes.view(-1, 4)[target_gt_idx]
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+
|
|
|
+ # assigned target scores
|
|
|
+ target_labels.clamp(0)
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|
+ target_scores = F.one_hot(target_labels, self.num_classes) # (b, h*w, 80)
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|
|
+ fg_scores_mask = fg_mask[:, :, None].repeat(1, 1, self.num_classes) # (b, h*w, 80)
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|
+ target_scores = torch.where(fg_scores_mask > 0, target_scores, 0)
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|
+
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|
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+ return target_labels, target_bboxes, target_scores
|
|
|
+
|
|
|
+
|
|
|
+# -------------------------- Basic Functions --------------------------
|
|
|
+def select_candidates_in_gts(xy_centers, gt_bboxes, eps=1e-9):
|
|
|
+ """select the positive anchors's center in gt
|
|
|
+ Args:
|
|
|
+ xy_centers (Tensor): shape(bs*n_max_boxes, num_total_anchors, 4)
|
|
|
+ gt_bboxes (Tensor): shape(bs, n_max_boxes, 4)
|
|
|
+ Return:
|
|
|
+ (Tensor): shape(bs, n_max_boxes, num_total_anchors)
|
|
|
+ """
|
|
|
+ n_anchors = xy_centers.size(0)
|
|
|
+ bs, n_max_boxes, _ = gt_bboxes.size()
|
|
|
+ _gt_bboxes = gt_bboxes.reshape([-1, 4])
|
|
|
+ xy_centers = xy_centers.unsqueeze(0).repeat(bs * n_max_boxes, 1, 1)
|
|
|
+ gt_bboxes_lt = _gt_bboxes[:, 0:2].unsqueeze(1).repeat(1, n_anchors, 1)
|
|
|
+ gt_bboxes_rb = _gt_bboxes[:, 2:4].unsqueeze(1).repeat(1, n_anchors, 1)
|
|
|
+ b_lt = xy_centers - gt_bboxes_lt
|
|
|
+ b_rb = gt_bboxes_rb - xy_centers
|
|
|
+ bbox_deltas = torch.cat([b_lt, b_rb], dim=-1)
|
|
|
+ bbox_deltas = bbox_deltas.reshape([bs, n_max_boxes, n_anchors, -1])
|
|
|
+ return (bbox_deltas.min(axis=-1)[0] > eps).to(gt_bboxes.dtype)
|
|
|
+
|
|
|
+
|
|
|
+def select_highest_overlaps(mask_pos, overlaps, n_max_boxes):
|
|
|
+ """if an anchor box is assigned to multiple gts,
|
|
|
+ the one with the highest iou will be selected.
|
|
|
+ Args:
|
|
|
+ mask_pos (Tensor): shape(bs, n_max_boxes, num_total_anchors)
|
|
|
+ overlaps (Tensor): shape(bs, n_max_boxes, num_total_anchors)
|
|
|
+ Return:
|
|
|
+ target_gt_idx (Tensor): shape(bs, num_total_anchors)
|
|
|
+ fg_mask (Tensor): shape(bs, num_total_anchors)
|
|
|
+ mask_pos (Tensor): shape(bs, n_max_boxes, num_total_anchors)
|
|
|
+ """
|
|
|
+ fg_mask = mask_pos.sum(axis=-2)
|
|
|
+ if fg_mask.max() > 1:
|
|
|
+ mask_multi_gts = (fg_mask.unsqueeze(1) > 1).repeat([1, n_max_boxes, 1])
|
|
|
+ max_overlaps_idx = overlaps.argmax(axis=1)
|
|
|
+ is_max_overlaps = F.one_hot(max_overlaps_idx, n_max_boxes)
|
|
|
+ is_max_overlaps = is_max_overlaps.permute(0, 2, 1).to(overlaps.dtype)
|
|
|
+ mask_pos = torch.where(mask_multi_gts, is_max_overlaps, mask_pos)
|
|
|
+ fg_mask = mask_pos.sum(axis=-2)
|
|
|
+ target_gt_idx = mask_pos.argmax(axis=-2)
|
|
|
+ return target_gt_idx, fg_mask , mask_pos
|
|
|
+
|
|
|
+
|
|
|
+def iou_calculator(box1, box2, eps=1e-9):
|
|
|
+ """Calculate iou for batch
|
|
|
+ Args:
|
|
|
+ box1 (Tensor): shape(bs, n_max_boxes, 1, 4)
|
|
|
+ box2 (Tensor): shape(bs, 1, num_total_anchors, 4)
|
|
|
+ Return:
|
|
|
+ (Tensor): shape(bs, n_max_boxes, num_total_anchors)
|
|
|
+ """
|
|
|
+ box1 = box1.unsqueeze(2) # [N, M1, 4] -> [N, M1, 1, 4]
|
|
|
+ box2 = box2.unsqueeze(1) # [N, M2, 4] -> [N, 1, M2, 4]
|
|
|
+ px1y1, px2y2 = box1[:, :, :, 0:2], box1[:, :, :, 2:4]
|
|
|
+ gx1y1, gx2y2 = box2[:, :, :, 0:2], box2[:, :, :, 2:4]
|
|
|
+ x1y1 = torch.maximum(px1y1, gx1y1)
|
|
|
+ x2y2 = torch.minimum(px2y2, gx2y2)
|
|
|
+ overlap = (x2y2 - x1y1).clip(0).prod(-1)
|
|
|
+ area1 = (px2y2 - px1y1).clip(0).prod(-1)
|
|
|
+ area2 = (gx2y2 - gx1y1).clip(0).prod(-1)
|
|
|
+ union = area1 + area2 - overlap + eps
|
|
|
+
|
|
|
+ return overlap / union
|