handle Timm pretrained backbones

Author: ai-fast-track

icevision/models/mmdet/common/utils.py

@@ -60,20 +60,30 @@ def build_model(
         cfg.model.roi_head.bbox_head.num_classes = num_classes - 1
         cfg.model.roi_head.mask_head.num_classes = num_classes - 1
 
-    if pretrained == True:
-        cfg.model.pretrained = True
+    # When using Timm backbone, loading the pretained weights are done icevision and not by mmdet code
+    # Check out here below
+    # Set cfg.model.pretrained to avoid mmdet loading them
+    if pretrained == True and (
+        isinstance(backbone, MMDetTimmBackboneConfig) and backbone.pretrained == True
+    ):
+        cfg.model.pretrained = None  # Timm pretrained backbones
     elif (pretrained == False) or (weights_path is not None):
         cfg.model.pretrained = None
 
     _model = build_detector(cfg.model, cfg.get("train_cfg"), cfg.get("test_cfg"))
     _model.init_weights()
 
+    # Load pretrained weights either:
+    # - by loading the whole pretrained model (COCO in general)
+    # - or only the pretrained backbone like Timm ones
     if pretrained:
         if weights_path is not None:
             print(
                 f"loading pretrained weights from user-provided url: {backbone.weights_url}"
             )
             load_checkpoint(_model, str(weights_path))
+        # We handle loading Timm (backbone) pretrained weights here
+        # the weights_url are stored in the backbone dict
         elif _model.backbone.weights_url is not None:
             weights_url = _model.backbone.weights_url
             print(f"loading default pretrained weights: {weights_url}")