draft for faster rcnn resnet v1 fpn feature extractor

research/object_detection/models/faster_rcnn_resnet_v1_fpn_keras_feature_extractor.py

@@ -88,8 +88,10 @@ class FasterRCNNResnetV1FPNKerasFeatureExtractor(
         `conv_hyperparams`.
 
     Raises:
-
+      ValueError: If `first_stage_features_stride` is not 8 or 16.
     """
+    if first_stage_features_stride != 8 and first_stage_features_stride != 16:
+      raise ValueError('`first_stage_features_stride` must be 8 or 16.')
     super(FasterRCNNResnetV1FPNKerasFeatureExtractor, self).__init__(
           is_training=is_training,
           first_stage_features_stride=first_stage_features_stride,
@@ -109,39 +111,38 @@ class FasterRCNNResnetV1FPNKerasFeatureExtractor(
     self._resnet_block_names = ['block1', 'block2', 'block3', 'block4']
     self.classification_backbone = None
     self._fpn_features_generator = None
-    self._coarse_feature_layers = []
 
   def build(self,):
     # TODO: Refine doc string
     """Build Resnet V1 FPN architecture."""
-    full_resnet_v1_model = self._resnet_v1_base_model(
-        batchnorm_training=self._train_batch_norm,
-        conv_hyperparams=(self._conv_hyperparams
-                          if self._override_base_feature_extractor_hyperparams
-                          else None),
-        min_depth=self._min_depth,
-        depth_multiplier=self._depth_multiplier,
-        classes=None,
-        weights=None,
-        include_top=False)
-    output_layers = _RESNET_MODEL_OUTPUT_LAYERS[self._resnet_v1_base_model_name]
-    outputs = [full_resnet_v1_model.get_layer(output_layer_name).output
-               for output_layer_name in output_layers]
-    self.classification_backbone = tf.keras.Model(
-        inputs=full_resnet_v1_model.inputs,
-        outputs=outputs)
-    self._depth_fn = lambda d: max(
-        int(d * self._depth_multiplier), self._min_depth)
-    self._base_fpn_max_level = min(self._fpn_max_level, 5)
-    self._num_levels = self._base_fpn_max_level + 1 - self._fpn_min_level
-    self._fpn_features_generator = (
-        feature_map_generators.KerasFpnTopDownFeatureMaps(
-            num_levels=self._num_levels,
-            depth=self._depth_fn(self._additional_layer_depth),
-            is_training=self._is_training,
-            conv_hyperparams=self._conv_hyperparams,
-            freeze_batchnorm=self._freeze_batchnorm,
-            name='FeatureMaps'))
+    # full_resnet_v1_model = self._resnet_v1_base_model(
+    #     batchnorm_training=self._train_batch_norm,
+    #     conv_hyperparams=(self._conv_hyperparams
+    #                       if self._override_base_feature_extractor_hyperparams
+    #                       else None),
+    #     min_depth=self._min_depth,
+    #     depth_multiplier=self._depth_multiplier,
+    #     classes=None,
+    #     weights=None,
+    #     include_top=False)
+    # output_layers = _RESNET_MODEL_OUTPUT_LAYERS[self._resnet_v1_base_model_name]
+    # outputs = [full_resnet_v1_model.get_layer(output_layer_name).output
+    #            for output_layer_name in output_layers]
+    # self.classification_backbone = tf.keras.Model(
+    #     inputs=full_resnet_v1_model.inputs,
+    #     outputs=outputs)
+    # self._depth_fn = lambda d: max(
+    #     int(d * self._depth_multiplier), self._min_depth)
+    # self._base_fpn_max_level = min(self._fpn_max_level, 5)
+    # self._num_levels = self._base_fpn_max_level + 1 - self._fpn_min_level
+    # self._fpn_features_generator = (
+    #     feature_map_generators.KerasFpnTopDownFeatureMaps(
+    #         num_levels=self._num_levels,
+    #         depth=self._depth_fn(self._additional_layer_depth),
+    #         is_training=self._is_training,
+    #         conv_hyperparams=self._conv_hyperparams,
+    #         freeze_batchnorm=self._freeze_batchnorm,
+    #         name='FeatureMaps'))
     # Construct coarse feature layers
     depth = self._depth_fn(self._additional_layer_depth)
     for i in range(self._base_fpn_max_level, self._fpn_max_level):
@@ -188,15 +189,74 @@ class FasterRCNNResnetV1FPNKerasFeatureExtractor(
     else:
       return resized_inputs
   
-  def _extract_proposal_features(self, preprocessed_inputs, scope=None):
-    # TODO: doc string
-    """"""
-    preprocessed_inputs = shape_utils.check_min_image_dim(
-        129, preprocessed_inputs)
+  # def _extract_proposal_features(self, preprocessed_inputs, scope=None):
+  #   # TODO: doc string
+  #   """"""
+  #   preprocessed_inputs = shape_utils.check_min_image_dim(
+  #       129, preprocessed_inputs)
+
+  #   with tf.name_scope(scope):
+  #     with tf.name_scope('ResnetV1FPN'):
+  #       image_features = self.classification_backbone(preprocessed_inputs)
+
+  #       feature_block_list = []
+  #       for level in range(self._fpn_min_level, self._base_fpn_max_level + 1):
+  #         feature_block_list.append('block{}'.format(level - 1))
+  #       feature_block_map = dict(
+  #           list(zip(self._resnet_block_names, image_features)))
+  #       fpn_input_image_features = [
+  #           (feature_block, feature_block_map[feature_block])
+  #           for feature_block in feature_block_list]
+  #       fpn_features = self._fpn_features_generator(fpn_input_image_features)
+
+  #       return fpn_features
+        
+  def get_proposal_feature_extractor_model(self, name=None):
+    """Returns a model that extracts first stage RPN features.
+
+    Extracts features using the first half of the Resnet v1 network.
+
+    Args:
+      name: A scope name to construct all variables within.
 
-    with tf.name_scope(scope):
+    Returns:
+      A Keras model that takes preprocessed_inputs:
+        A [batch, height, width, channels] float32 tensor
+        representing a batch of images.
+    """
+    with tf.name_scope(name):
       with tf.name_scope('ResnetV1FPN'):
-        image_features = self.classification_backbone(preprocessed_inputs)
+        full_resnet_v1_model = self._resnet_v1_base_model(
+            batchnorm_training=self._train_batch_norm,
+            conv_hyperparams=(self._conv_hyperparams
+                              if self._override_base_feature_extractor_hyperparams
+                              else None),
+            min_depth=self._min_depth,
+            depth_multiplier=self._depth_multiplier,
+            classes=None,
+            weights=None,
+            include_top=False)
+        output_layers = _RESNET_MODEL_OUTPUT_LAYERS[self._resnet_v1_base_model_name]
+        outputs = [full_resnet_v1_model.get_layer(output_layer_name).output
+                  for output_layer_name in output_layers]
+        self.classification_backbone = tf.keras.Model(
+            inputs=full_resnet_v1_model.inputs,
+            outputs=outputs)
+        backbone_outputs = self.classification_backbone(full_resnet_v1_model.inputs)
+
+        # construct FPN feature generator
+        self._depth_fn = lambda d: max(
+            int(d * self._depth_multiplier), self._min_depth)
+        self._base_fpn_max_level = min(self._fpn_max_level, 5)
+        self._num_levels = self._base_fpn_max_level + 1 - self._fpn_min_level
+        self._fpn_features_generator = (
+            feature_map_generators.KerasFpnTopDownFeatureMaps(
+                num_levels=self._num_levels,
+                depth=self._depth_fn(self._additional_layer_depth),
+                is_training=self._is_training,
+                conv_hyperparams=self._conv_hyperparams,
+                freeze_batchnorm=self._freeze_batchnorm,
+                name='FeatureMaps'))
         
         feature_block_list = []
         for level in range(self._fpn_min_level, self._base_fpn_max_level + 1):
@@ -208,22 +268,24 @@ class FasterRCNNResnetV1FPNKerasFeatureExtractor(
             for feature_block in feature_block_list]
         fpn_features = self._fpn_features_generator(fpn_input_image_features)
 
-        return fpn_features
-        
+        feature_extractor_model = tf.keras.models.Model(
+            inputs=self.full_resnet_v1_model.inputs, outputs=fpn_features)
+        return feature_extractor_model
 
-  def _extract_box_classifier_features(self, proposal_feature_maps, scope=None):
-    with tf.name_scope(scope):
-      with tf.name_scope('ResnetV1FPN'):
-        feature_maps = []
-        for level in range(self._fpn_min_level, self._base_fpn_max_level + 1):
-          feature_maps.append(proposal_feature_maps['top_down_block{}'.format(level-1)])
-        self.last_feature_map = proposal_feature_maps['top_down_block{}'.format(
-            self._base_fpn_max_level - 1)]
+  # def _extract_box_classifier_features(self, proposal_feature_maps, scope=None):
+  #   with tf.name_scope(scope):
+  #     with tf.name_scope('ResnetV1FPN'):
+  #       feature_maps = []
+  #       for level in range(self._fpn_min_level, self._base_fpn_max_level + 1):
+  #         feature_maps.append(proposal_feature_maps['top_down_block{}'.format(level-1)])
+  #       self.last_feature_map = proposal_feature_maps['top_down_block{}'.format(
+  #           self._base_fpn_max_level - 1)]
 
-        for coarse_feature_layers in self._coarse_feature_layers:
-          for layer in coarse_feature_layers:
-            last_feature_map = layer(last_feature_map)
-          feature_maps.append(self.last_feature_map)
+  #       for coarse_feature_layers in self._coarse_feature_layers:
+  #         for layer in coarse_feature_layers:
+  #           last_feature_map = layer(last_feature_map)
+  #         feature_maps.append(self.last_feature_map)
 
-        return feature_maps
+  #       return feature_maps
 
+  def get_box_classifier_feature_extractor_model(self, name=None):