Add forward_intermediates API to Hiera for features_only=True support

Author: rwightman

tests/test_models.py

@@ -49,15 +49,15 @@
 
 # models with forward_intermediates() and support for FeatureGetterNet features_only wrapper
 FEAT_INTER_FILTERS = [
-    'vit_*', 'twins_*', 'deit*', 'beit*', 'mvitv2*', 'eva*', 'samvit_*', 'flexivit*'
+    'vit_*', 'twins_*', 'deit*', 'beit*', 'mvitv2*', 'eva*', 'samvit_*', 'flexivit*', 'hiera_*'
 ]
 
 # transformer models don't support many of the spatial / feature based model functionalities
 NON_STD_FILTERS = [
     'vit_*', 'tnt_*', 'pit_*', 'coat_*', 'cait_*', '*mixer_*', 'gmlp_*', 'resmlp_*', 'twins_*',
     'convit_*', 'levit*', 'visformer*', 'deit*', 'xcit_*', 'crossvit_*', 'beit*',
     'poolformer_*', 'volo_*', 'sequencer2d_*', 'mvitv2*', 'gcvit*', 'efficientformer*',
-    'eva_*', 'flexivit*', 'eva02*', 'samvit_*', 'efficientvit_m*', 'tiny_vit_*'
+    'eva_*', 'flexivit*', 'eva02*', 'samvit_*', 'efficientvit_m*', 'tiny_vit_*', 'hiera_*'
 ]
 NUM_NON_STD = len(NON_STD_FILTERS)
 

timm/models/hiera.py

@@ -37,6 +37,7 @@
 
 from ._registry import generate_default_cfgs, register_model
 from ._builder import build_model_with_cfg
+from ._features import feature_take_indices
 
 
 def conv_nd(n: int) -> Type[nn.Module]:
@@ -517,7 +518,7 @@ def __init__(
         # Transformer blocks
         cur_stage = 0
         self.blocks = nn.ModuleList()
-
+        self.feature_info = []
         for i in range(depth):
             dim_out = embed_dim
             # Mask unit or global attention.
@@ -543,8 +544,10 @@ def __init__(
                 window_size=flat_mu_size,
                 use_mask_unit_attn=use_mask_unit_attn,
             )
-
             embed_dim = dim_out
+            if i in self.stage_ends:
+                self.feature_info += [
+                    dict(num_chs=dim_out, reduction=2**(cur_stage+2), module=f'blocks.{self.stage_ends[cur_stage]}')]
             self.blocks.append(block)
 
         self.norm = norm_layer(embed_dim)
@@ -616,6 +619,57 @@ def _pos_embed(self, x) -> torch.Tensor:
         x = x + pos_embed
         return x
 
+    def forward_intermediates(
+            self,
+            x: torch.Tensor,
+            indices: Optional[Union[int, List[int], Tuple[int]]] = None,
+            norm: bool = False,
+            stop_early: bool = True,
+            output_fmt: str = 'NCHW',
+            intermediates_only: bool = False,
+    ) -> Union[List[torch.Tensor], Tuple[torch.Tensor, List[torch.Tensor]]]:
+        """ Forward features that returns intermediates.
+
+        Args:
+            x: Input image tensor
+            indices: Take last n blocks if int, all if None, select matching indices if sequence
+            norm: Apply norm layer to all intermediates
+            stop_early: Stop iterating over blocks when last desired intermediate hit
+            output_fmt: Shape of intermediate feature outputs
+            intermediates_only: Only return intermediate features
+        Returns:
+
+        """
+        assert not norm, 'normalization of features not supported'
+        assert output_fmt in ('NCHW',), 'Output format must be one of NCHW.'
+        take_indices, max_index = feature_take_indices(len(self.stage_ends), indices)
+
+        # FIXME using existing return_intermediates support in model, doesn't have early stopping.
+        x, intermediates = self.forward_features(x, return_intermediates=True)
+        intermediates = [y.permute(0, 3, 1, 2) for i, y in enumerate(intermediates) if i in take_indices]
+        if intermediates_only:
+            return intermediates
+
+        return x, intermediates
+
+    def prune_intermediate_layers(
+            self,
+            n: Union[int, List[int], Tuple[int]] = 1,
+            prune_norm: bool = False,
+            prune_head: bool = True,
+    ):
+        """ Prune layers not required for specified intermediates.
+        """
+        take_indices, max_index = feature_take_indices(len(self.stage_ends), n)
+        max_index = self.stage_ends[max_index]
+        self.blocks = self.blocks[:max_index + 1]  # truncate blocks
+        if prune_head:
+            # norm part of head for this model, equivalent to fc_norm in other vit.
+            self.norm = nn.Identity()
+            self.head = nn.Identity()
+        return take_indices
+
+
     def forward_features(
             self,
             x: torch.Tensor,