add faster rcnn resnet v1 fpn feature extractor to model builder

research/object_detection/builders/model_builder.py

@@ -52,6 +52,7 @@ if tf_version.is_tf2():
   from object_detection.models import faster_rcnn_inception_resnet_v2_keras_feature_extractor as frcnn_inc_res_keras
   from object_detection.models import faster_rcnn_resnet_keras_feature_extractor as frcnn_resnet_keras
   from object_detection.models import ssd_resnet_v1_fpn_keras_feature_extractor as ssd_resnet_v1_fpn_keras
+  from object_detection.models import faster_rcnn_resnet_v1_fpn_keras_feature_extractor as frcnn_resnet_fpn_keras
   from object_detection.models.ssd_mobilenet_v1_fpn_keras_feature_extractor import SSDMobileNetV1FpnKerasFeatureExtractor
   from object_detection.models.ssd_mobilenet_v1_keras_feature_extractor import SSDMobileNetV1KerasFeatureExtractor
   from object_detection.models.ssd_mobilenet_v2_fpn_keras_feature_extractor import SSDMobileNetV2FpnKerasFeatureExtractor
@@ -109,6 +110,12 @@ if tf_version.is_tf2():
           frcnn_resnet_keras.FasterRCNNResnet152KerasFeatureExtractor,
       'faster_rcnn_inception_resnet_v2_keras':
       frcnn_inc_res_keras.FasterRCNNInceptionResnetV2KerasFeatureExtractor,
+      'fasret_rcnn_resnet50_fpn_keras':
+          frcnn_resnet_fpn_keras.FasterRCNNResnet50FPNKerasFeatureExtractor,
+      'fasret_rcnn_resnet101_fpn_keras':
+          frcnn_resnet_fpn_keras.FasterRCNNResnet101FPNKerasFeatureExtractor,
+      'fasret_rcnn_resnet152_fpn_keras':
+          frcnn_resnet_fpn_keras.FasterRCNNResnet152FPNKerasFeatureExtractor,
   }
 
   CENTER_NET_EXTRACTOR_FUNCTION_MAP = {