Fixed bug in computing map metric for images with either no ground tr…

CHANGELOG.md

@@ -112,6 +112,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed unsafe log operation in `TweedieDeviace` for power=1 ([#847](https://github.com/PyTorchLightning/metrics/pull/847))
 
 
+- Fixed bug in MAP metric related to either no ground truth or no predictions ([#884](https://github.com/PyTorchLightning/metrics/pull/884))
+
+
 ## [0.7.2] - 2022-02-10
 
 ### Fixed

tests/detection/test_map.py

@@ -266,6 +266,50 @@ def test_empty_metric():
  metric.compute()
 
 
+@pytest.mark.skipif(_pytest_condition, reason="test requires that pycocotools and torchvision=>0.8.0 is installed")
+def test_missing_pred():
+ """One good detection, one false negative.
+
+ Map should be lower than 1. Actually it is 0.5, but the exact value depends on where we are sampling (i.e. recall's
+ values)
+ """
+ gts = [
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), labels=torch.IntTensor([0])),
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), labels=torch.IntTensor([0])),
+ ]
+ preds = [
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), scores=torch.Tensor([0.9]), labels=torch.IntTensor([0])),
+ # Empty prediction
+ dict(boxes=torch.Tensor([]), scores=torch.Tensor([]), labels=torch.IntTensor([])),
+ ]
+ metric = MeanAveragePrecision()
+ metric.update(preds, gts)
+ result = metric.compute()
+ assert result["map"] < 1, "MAP cannot be 1, as there is a missing prediction."
+
+
+@pytest.mark.skipif(_pytest_condition, reason="test requires that pycocotools and torchvision=>0.8.0 is installed")
+def test_missing_gt():
+ """The symmetric case of test_missing_pred.
+
+ One good detection, one false positive. Map should be lower than 1. Actually it is 0.5, but the exact value depends
+ on where we are sampling (i.e. recall's values)
+ """
+ gts = [
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), labels=torch.IntTensor([0])),
+ dict(boxes=torch.Tensor([]), labels=torch.IntTensor([])),
+ ]
+ preds = [
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), scores=torch.Tensor([0.9]), labels=torch.IntTensor([0])),
+ dict(boxes=torch.Tensor([[10, 20, 15, 25]]), scores=torch.Tensor([0.95]), labels=torch.IntTensor([0])),
+ ]
+
+ metric = MeanAveragePrecision()
+ metric.update(preds, gts)
+ result = metric.compute()
+ assert result["map"] < 1, "MAP cannot be 1, as there is an image with no ground truth, but some predictions."
+
+
 @pytest.mark.skipif(_pytest_condition, reason="test requires that torchvision=>0.8.0 is installed")
 def test_error_on_wrong_input():
  """Test class input validation."""

torchmetrics/detection/map.py

@@ -367,6 +367,60 @@ def _compute_iou(self, idx: int, class_id: int, max_det: int) -> Tensor:
  ious = box_iou(det, gt)
  return ious
 
+ def __evaluate_image_gt_no_preds(
+ self, gt: Tensor, gt_label_mask: Tensor, area_range: Tuple[int, int], nb_iou_thrs: int
+ ) -> Dict[str, Any]:
+ """Some GT but no predictions."""
+ # GTs
+ gt = gt[gt_label_mask]
+ nb_gt = len(gt)
+ areas = box_area(gt)
+ ignore_area = (areas < area_range[0]) | (areas > area_range[1])
+ gt_ignore, _ = torch.sort(ignore_area.to(torch.uint8))
+ gt_ignore = gt_ignore.to(torch.bool)
+
+ # Detections
+ nb_det = 0
+ det_ignore = torch.zeros((nb_iou_thrs, nb_det), dtype=torch.bool, device=self.device)
+
+ return {
+ "dtMatches": torch.zeros((nb_iou_thrs, nb_det), dtype=torch.bool, device=self.device),
+ "gtMatches": torch.zeros((nb_iou_thrs, nb_gt), dtype=torch.bool, device=self.device),
+ "dtScores": torch.zeros(nb_det, dtype=torch.bool, device=self.device),
+ "gtIgnore": gt_ignore,
+ "dtIgnore": det_ignore,
+ }
+
+ def __evaluate_image_preds_no_gt(
+ self, det: Tensor, idx: int, det_label_mask: Tensor, max_det: int, area_range: Tuple[int, int], nb_iou_thrs: int
+ ) -> Dict[str, Any]:
+ """Some predictions but no GT."""
+ # GTs
+ nb_gt = 0
+ gt_ignore = torch.zeros(nb_gt, dtype=torch.bool, device=self.device)
+
+ # Detections
+ det = det[det_label_mask]
+ scores = self.detection_scores[idx]
+ scores_filtered = scores[det_label_mask]
+ scores_sorted, dtind = torch.sort(scores_filtered, descending=True)
+ det = det[dtind]
+ if len(det) > max_det:
+ det = det[:max_det]
+ nb_det = len(det)
+ det_areas = box_area(det).to(self.device)
+ det_ignore_area = (det_areas < area_range[0]) | (det_areas > area_range[1])
+ ar = det_ignore_area.reshape((1, nb_det))
+ det_ignore = torch.repeat_interleave(ar, nb_iou_thrs, 0)
+
+ return {
+ "dtMatches": torch.zeros((nb_iou_thrs, nb_det), dtype=torch.bool, device=self.device),
+ "gtMatches": torch.zeros((nb_iou_thrs, nb_gt), dtype=torch.bool, device=self.device),
+ "dtScores": scores_sorted,
+ "gtIgnore": gt_ignore,
+ "dtIgnore": det_ignore,
+ }
+
  def _evaluate_image(
  self, idx: int, class_id: int, area_range: Tuple[int, int], max_det: int, ious: dict
  ) -> Optional[dict]:
@@ -388,11 +442,24 @@ def _evaluate_image(
  det = self.detection_boxes[idx]
  gt_label_mask = self.groundtruth_labels[idx] == class_id
  det_label_mask = self.detection_labels[idx] == class_id
- if len(gt_label_mask) == 0 or len(det_label_mask) == 0:
+
+ # No Gt and No predictions --> ignore image
+ if len(gt_label_mask) == 0 and len(det_label_mask) == 0:
  return None
+
+ nb_iou_thrs = len(self.iou_thresholds)
+
+ # Some GT but no predictions
+ if len(gt_label_mask) > 0 and len(det_label_mask) == 0:
+ return self.__evaluate_image_gt_no_preds(gt, gt_label_mask, area_range, nb_iou_thrs)
+
+ # Some predictions but no GT
+ if len(gt_label_mask) == 0 and len(det_label_mask) >= 0:
+ return self.__evaluate_image_preds_no_gt(det, idx, det_label_mask, max_det, area_range, nb_iou_thrs)
+
  gt = gt[gt_label_mask]
  det = det[det_label_mask]
- if len(gt) == 0 and len(det) == 0:
+ if gt.numel() == 0 and det.numel() == 0:
  return None
 
  areas = box_area(gt)
@@ -424,10 +491,11 @@ def _evaluate_image(
  for idx_iou, t in enumerate(self.iou_thresholds):
  for idx_det, _ in enumerate(det):
  m = MeanAveragePrecision._find_best_gt_match(t, gt_matches, idx_iou, gt_ignore, ious, idx_det)
- if m != -1:
- det_ignore[idx_iou, idx_det] = gt_ignore[m]
- det_matches[idx_iou, idx_det] = 1
- gt_matches[idx_iou, m] = 1
+ if m == -1:
+ continue
+ det_ignore[idx_iou, idx_det] = gt_ignore[m]
+ det_matches[idx_iou, idx_det] = 1
+ gt_matches[idx_iou, m] = 1
 
  # set unmatched detections outside of area range to ignore
  det_areas = box_area(det)