Ensure target class indices are of type long in loss calculations (#4143)

* Ensure target class indices are of type long in loss calculations

* update changelog

Author: eugene123tw

CHANGELOG.md

@@ -132,6 +132,8 @@ All notable changes to this project will be documented in this file.
   (<https://github.com/openvinotoolkit/training_extensions/pull/4131>)
 - Fix tensor type compatibility in dynamic soft label assigner and RTMDet head
   (<https://github.com/openvinotoolkit/training_extensions/pull/4140>)
+- Fix DETR target class indices are of type long in loss calculations
+  (<https://github.com/openvinotoolkit/training_extensions/pull/4143>)
 
 ## \[v2.1.0\]
 

src/otx/algo/detection/losses/rtdetr_loss.py

@@ -77,7 +77,7 @@ def loss_labels_vfl(
         src_logits = outputs["pred_logits"]
         target_classes_o = torch.cat([t["labels"][J] for t, (_, J) in zip(targets, indices)])
         target_classes = torch.full(src_logits.shape[:2], self.num_classes, dtype=torch.int64, device=src_logits.device)
-        target_classes[idx] = target_classes_o
+        target_classes[idx] = target_classes_o.long()
         target = nn.functional.one_hot(target_classes, num_classes=self.num_classes + 1)[..., :-1]
 
         target_score_o = torch.zeros_like(target_classes, dtype=src_logits.dtype)

src/otx/algo/detection/utils/matchers/hungarian_matcher.py

@@ -71,7 +71,7 @@ def forward(
         out_bbox = outputs["pred_boxes"].flatten(0, 1)  # [batch_size * num_queries, 4]
 
         # Also concat the target labels and boxes
-        tgt_ids = torch.cat([v["labels"] for v in targets])
+        tgt_ids = torch.cat([v["labels"] for v in targets]).long()
         tgt_bbox = torch.cat([v["boxes"] for v in targets])
 
         # Compute the classification cost. Contrary to the loss, we don't use the NLL,