text: # Copyright 2017 The TensorFlow Authors. All Rights Reserved.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  # ==============================================================================
  
  """A function to build a DetectionModel from configuration."""
  from object_detection.builders import anchor_generator_builder
  from object_detection.builders import box_coder_builder
  from object_detection.builders import box_predictor_builder
  from object_detection.builders import hyperparams_builder
  from object_detection.builders import image_resizer_builder
  from object_detection.builders import losses_builder
  from object_detection.builders import matcher_builder
  from object_detection.builders import post_processing_builder
  from object_detection.builders import region_similarity_calculator_builder as sim_calc
  from object_detection.core import box_predictor
  from object_detection.meta_architectures import faster_rcnn_meta_arch
  from object_detection.meta_architectures import rfcn_meta_arch
  from object_detection.meta_architectures import ssd_meta_arch
  from object_detection.models import faster_rcnn_inception_resnet_v2_feature_extractor as frcnn_inc_res
  from object_detection.models import faster_rcnn_inception_v2_feature_extractor as frcnn_inc_v2
  from object_detection.models import faster_rcnn_nas_feature_extractor as frcnn_nas
  from object_detection.models import faster_rcnn_pnas_feature_extractor as frcnn_pnas
  from object_detection.models import faster_rcnn_resnet_v1_feature_extractor as frcnn_resnet_v1
  from object_detection.models import ssd_resnet_v1_fpn_feature_extractor as ssd_resnet_v1_fpn
  from object_detection.models.embedded_ssd_mobilenet_v1_feature_extractor import EmbeddedSSDMobileNetV1FeatureExtractor
  from object_detection.models.ssd_inception_v2_feature_extractor import SSDInceptionV2FeatureExtractor
  from object_detection.models.ssd_inception_v3_feature_extractor import SSDInceptionV3FeatureExtractor
  from object_detection.models.ssd_mobilenet_v1_feature_extractor import SSDMobileNetV1FeatureExtractor
  from object_detection.models.ssd_mobilenet_v2_feature_extractor import SSDMobileNetV2FeatureExtractor
  from object_detection.protos import model_pb2
  
  # A map of names to SSD feature extractors.
  SSD_FEATURE_EXTRACTOR_CLASS_MAP = {
      'ssd_inception_v2': SSDInceptionV2FeatureExtractor,
      'ssd_inception_v3': SSDInceptionV3FeatureExtractor,
      'ssd_mobilenet_v1': SSDMobileNetV1FeatureExtractor,
      'ssd_mobilenet_v2': SSDMobileNetV2FeatureExtractor,
      'ssd_resnet50_v1_fpn': ssd_resnet_v1_fpn.SSDResnet50V1FpnFeatureExtractor,
      'ssd_resnet101_v1_fpn': ssd_resnet_v1_fpn.SSDResnet101V1FpnFeatureExtractor,
      'ssd_resnet152_v1_fpn': ssd_resnet_v1_fpn.SSDResnet152V1FpnFeatureExtractor,
      'embedded_ssd_mobilenet_v1': EmbeddedSSDMobileNetV1FeatureExtractor,
  }
  
  # A map of names to Faster R-CNN feature extractors.
  FASTER_RCNN_FEATURE_EXTRACTOR_CLASS_MAP = {
      'faster_rcnn_nas':
      frcnn_nas.FasterRCNNNASFeatureExtractor,
      'faster_rcnn_pnas':
      frcnn_pnas.FasterRCNNPNASFeatureExtractor,
      'faster_rcnn_inception_resnet_v2':
      frcnn_inc_res.FasterRCNNInceptionResnetV2FeatureExtractor,
      'faster_rcnn_inception_v2':
      frcnn_inc_v2.FasterRCNNInceptionV2FeatureExtractor,
      'faster_rcnn_resnet50':
      frcnn_resnet_v1.FasterRCNNResnet50FeatureExtractor,
      'faster_rcnn_resnet101':
      frcnn_resnet_v1.FasterRCNNResnet101FeatureExtractor,
      'faster_rcnn_resnet152':
      frcnn_resnet_v1.FasterRCNNResnet152FeatureExtractor,
  }
  
  
  def build(model_config, is_training, add_summaries=True,
            add_background_class=True):
    """Builds a DetectionModel based on the model config.
  
    Args:
      model_config: A model.proto object containing the config for the desired
        DetectionModel.
      is_training: True if this model is being built for training purposes.
      add_summaries: Whether to add tensorflow summaries in the model graph.
      add_background_class: Whether to add an implicit background class to one-hot
        encodings of groundtruth labels. Set to false if using groundtruth labels
        with an explicit background class or using multiclass scores instead of
        truth in the case of distillation. Ignored in the case of faster_rcnn.
    Returns:
      DetectionModel based on the config.
  
    Raises:
      ValueError: On invalid meta architecture or model.
    """
    if not isinstance(model_config, model_pb2.DetectionModel):
      raise ValueError('model_config not of type model_pb2.DetectionModel.')
    meta_architecture = model_config.WhichOneof('model')
    if meta_architecture == 'ssd':
      return _build_ssd_model(model_config.ssd, is_training, add_summaries,
                              add_background_class)
    if meta_architecture == 'faster_rcnn':
      return _build_faster_rcnn_model(model_config.faster_rcnn, is_training,
                                      add_summaries)
    raise ValueError('Unknown meta architecture: {}'.format(meta_architecture))
  
  
  def _build_ssd_feature_extractor(feature_extractor_config, is_training,
                                   reuse_weights=None):
    """Builds a ssd_meta_arch.SSDFeatureExtractor based on config.
  
    Args:
      feature_extractor_config: A SSDFeatureExtractor proto config from ssd.proto.
      is_training: True if this feature extractor is being built for training.
      reuse_weights: if the feature extractor should reuse weights.
  
    Returns:
      ssd_meta_arch.SSDFeatureExtractor based on config.
  
    Raises:
      ValueError: On invalid feature extractor type.
    """
    feature_type = feature_extractor_config.type
    depth_multiplier = feature_extractor_config.depth_multiplier
    min_depth = feature_extractor_config.min_depth
    pad_to_multiple = feature_extractor_config.pad_to_multiple
    use_explicit_padding = feature_extractor_config.use_explicit_padding
    use_depthwise = feature_extractor_config.use_depthwise
    conv_hyperparams = hyperparams_builder.build(
        feature_extractor_config.conv_hyperparams, is_training)
    override_base_feature_extractor_hyperparams = (
        feature_extractor_config.override_base_feature_extractor_hyperparams)
  
    if feature_type not in SSD_FEATURE_EXTRACTOR_CLASS_MAP:
      raise ValueError('Unknown ssd feature_extractor: {}'.format(feature_type))
  
    feature_extractor_class = SSD_FEATURE_EXTRACTOR_CLASS_MAP[feature_type]
    return feature_extractor_class(
        is_training, depth_multiplier, min_depth, pad_to_multiple,
        conv_hyperparams, reuse_weights, use_explicit_padding, use_depthwise,
        override_base_feature_extractor_hyperparams)
  
  
  def _build_ssd_model(ssd_config, is_training, add_summaries,
                       add_background_class=True):
    """Builds an SSD detection model based on the model config.
  
    Args:
      ssd_config: A ssd.proto object containing the config for the desired
        SSDMetaArch.
      is_training: True if this model is being built for training purposes.
      add_summaries: Whether to add tf summaries in the model.
      add_background_class: Whether to add an implicit background class to one-hot
        encodings of groundtruth labels. Set to false if using groundtruth labels
        with an explicit background class or using multiclass scores instead of
        truth in the case of distillation.
    Returns:
      SSDMetaArch based on the config.
  
    Raises:
      ValueError: If ssd_config.type is not recognized (i.e. not registered in
        model_class_map).
    """
    num_classes = ssd_config.num_classes
  
    # Feature extractor
    feature_extractor = _build_ssd_feature_extractor(
        feature_extractor_config=ssd_config.feature_extractor,
        is_training=is_training)
  
    box_coder = box_coder_builder.build(ssd_config.box_coder)
    matcher = matcher_builder.build(ssd_config.matcher)
    region_similarity_calculator = sim_calc.build(
        ssd_config.similarity_calculator)
    encode_background_as_zeros = ssd_config.encode_background_as_zeros
    negative_class_weight = ssd_config.negative_class_weight
    ssd_box_predictor = box_predictor_builder.build(hyperparams_builder.build,
                                                    ssd_config.box_predictor,
                                                    is_training, num_classes)
    anchor_generator = anchor_generator_builder.build(
        ssd_config.anchor_generator)
    image_resizer_fn = image_resizer_builder.build(ssd_config.image_resizer)
    non_max_suppression_fn, score_conversion_fn = post_processing_builder.build(
        ssd_config.post_processing)
    (classification_loss, localization_loss, classification_weight,
     localization_weight, hard_example_miner,
     random_example_sampler) = losses_builder.build(ssd_config.loss)
    normalize_loss_by_num_matches = ssd_config.normalize_loss_by_num_matches
    normalize_loc_loss_by_codesize = ssd_config.normalize_loc_loss_by_codesize
  
    return ssd_meta_arch.SSDMetaArch(
        is_training,
        anchor_generator,
        ssd_box_predictor,
        box_coder,
        feature_extractor,
        matcher,
        region_similarity_calculator,
        encode_background_as_zeros,
        negative_class_weight,
        image_resizer_fn,
        non_max_suppression_fn,
        score_conversion_fn,
        classification_loss,
        localization_loss,
        classification_weight,
        localization_weight,
        normalize_loss_by_num_matches,
        hard_example_miner,
        add_summaries=add_summaries,
        normalize_loc_loss_by_codesize=normalize_loc_loss_by_codesize,
        freeze_batchnorm=ssd_config.freeze_batchnorm,
        inplace_batchnorm_update=ssd_config.inplace_batchnorm_update,
        add_background_class=add_background_class,
        random_example_sampler=random_example_sampler)
  
  
  def _build_faster_rcnn_feature_extractor(
      feature_extractor_config, is_training, reuse_weights=None,
      inplace_batchnorm_update=False):
    """Builds a faster_rcnn_meta_arch.FasterRCNNFeatureExtractor based on config.
  
    Args:
      feature_extractor_config: A FasterRcnnFeatureExtractor proto config from
        faster_rcnn.proto.
      is_training: True if this feature extractor is being built for training.
      reuse_weights: if the feature extractor should reuse weights.
      inplace_batchnorm_update: Whether to update batch_norm inplace during
        training. This is required for batch norm to work correctly on TPUs. When
        this is false, user must add a control dependency on
        tf.GraphKeys.UPDATE_OPS for train/loss op in order to update the batch
        norm moving average parameters.
  
    Returns:
      faster_rcnn_meta_arch.FasterRCNNFeatureExtractor based on config.
  
    Raises:
      ValueError: On invalid feature extractor type.
    """
    if inplace_batchnorm_update:
      raise ValueError('inplace batchnorm updates not supported.')
    feature_type = feature_extractor_config.type
    first_stage_features_stride = (
        feature_extractor_config.first_stage_features_stride)
    batch_norm_trainable = feature_extractor_config.batch_norm_trainable
  
    if feature_type not in FASTER_RCNN_FEATURE_EXTRACTOR_CLASS_MAP:
      raise ValueError('Unknown Faster R-CNN feature_extractor: {}'.format(
          feature_type))
    feature_extractor_class = FASTER_RCNN_FEATURE_EXTRACTOR_CLASS_MAP[
        feature_type]
    return feature_extractor_class(
        is_training, first_stage_features_stride,
        batch_norm_trainable, reuse_weights)
  
  
  def _build_faster_rcnn_model(frcnn_config, is_training, add_summaries):
    """Builds a Faster R-CNN or R-FCN detection model based on the model config.
  
    Builds R-FCN model if the second_stage_box_predictor in the config is of type
    `rfcn_box_predictor` else builds a Faster R-CNN model.
  
    Args:
      frcnn_config: A faster_rcnn.proto object containing the config for the
        desired FasterRCNNMetaArch or RFCNMetaArch.
      is_training: True if this model is being built for training purposes.
      add_summaries: Whether to add tf summaries in the model.
  
    Returns:
      FasterRCNNMetaArch based on the config.
  
    Raises:
      ValueError: If frcnn_config.type is not recognized (i.e. not registered in
        model_class_map).
    """
    num_classes = frcnn_config.num_classes
    image_resizer_fn = image_resizer_builder.build(frcnn_config.image_resizer)
  
    feature_extractor = _build_faster_rcnn_feature_extractor(
        frcnn_config.feature_extractor, is_training,
        frcnn_config.inplace_batchnorm_update)
  
    number_of_stages = frcnn_config.number_of_stages
    first_stage_anchor_generator = anchor_generator_builder.build(
        frcnn_config.first_stage_anchor_generator)
  
    first_stage_atrous_rate = frcnn_config.first_stage_atrous_rate
    first_stage_box_predictor_arg_scope_fn = hyperparams_builder.build(
        frcnn_config.first_stage_box_predictor_conv_hyperparams, is_training)
    first_stage_box_predictor_kernel_size = (
        frcnn_config.first_stage_box_predictor_kernel_size)
    first_stage_box_predictor_depth = frcnn_config.first_stage_box_predictor_depth
    first_stage_minibatch_size = frcnn_config.first_stage_minibatch_size
    first_stage_positive_balance_fraction = (
        frcnn_config.first_stage_positive_balance_fraction)
    first_stage_nms_score_threshold = frcnn_config.first_stage_nms_score_threshold
    first_stage_nms_iou_threshold = frcnn_config.first_stage_nms_iou_threshold
    first_stage_max_proposals = frcnn_config.first_stage_max_proposals
    first_stage_loc_loss_weight = (
        frcnn_config.first_stage_localization_loss_weight)
    first_stage_obj_loss_weight = frcnn_config.first_stage_objectness_loss_weight
  
    initial_crop_size = frcnn_config.initial_crop_size
    maxpool_kernel_size = frcnn_config.maxpool_kernel_size
    maxpool_stride = frcnn_config.maxpool_stride
  
    second_stage_box_predictor = box_predictor_builder.build(
        hyperparams_builder.build,
        frcnn_config.second_stage_box_predictor,
        is_training=is_training,
        num_classes=num_classes)
    second_stage_batch_size = frcnn_config.second_stage_batch_size
    second_stage_balance_fraction = frcnn_config.second_stage_balance_fraction
    (second_stage_non_max_suppression_fn, second_stage_score_conversion_fn
    ) = post_processing_builder.build(frcnn_config.second_stage_post_processing)
    second_stage_localization_loss_weight = (
        frcnn_config.second_stage_localization_loss_weight)
    second_stage_classification_loss = (
        losses_builder.build_faster_rcnn_classification_loss(
            frcnn_config.second_stage_classification_loss))
    second_stage_classification_loss_weight = (
        frcnn_config.second_stage_classification_loss_weight)
    second_stage_mask_prediction_loss_weight = (
        frcnn_config.second_stage_mask_prediction_loss_weight)
  
    hard_example_miner = None
    if frcnn_config.HasField('hard_example_miner'):
      hard_example_miner = losses_builder.build_hard_example_miner(
          frcnn_config.hard_example_miner,
          second_stage_classification_loss_weight,
          second_stage_localization_loss_weight)
  
    common_kwargs = {
        'is_training': is_training,
        'num_classes': num_classes,
        'image_resizer_fn': image_resizer_fn,
        'feature_extractor': feature_extractor,
        'number_of_stages': number_of_stages,
        'first_stage_anchor_generator': first_stage_anchor_generator,
        'first_stage_atrous_rate': first_stage_atrous_rate,
        'first_stage_box_predictor_arg_scope_fn':
        first_stage_box_predictor_arg_scope_fn,
        'first_stage_box_predictor_kernel_size':
        first_stage_box_predictor_kernel_size,
        'first_stage_box_predictor_depth': first_stage_box_predictor_depth,
        'first_stage_minibatch_size': first_stage_minibatch_size,
        'first_stage_positive_balance_fraction': first_stage_positive_balance_fraction,
        'first_stage_nms_score_threshold': first_stage_nms_score_threshold,
        'first_stage_nms_iou_threshold': first_stage_nms_iou_threshold,
        'first_stage_max_proposals': first_stage_max_proposals,
        'first_stage_localization_loss_weight': first_stage_loc_loss_weight,
        'first_stage_objectness_loss_weight': first_stage_obj_loss_weight,
        'second_stage_batch_size': second_stage_batch_size,
        'second_stage_balance_fraction': second_stage_balance_fraction,
        'second_stage_non_max_suppression_fn': second_stage_non_max_suppression_fn,
        'second_stage_score_conversion_fn': second_stage_score_conversion_fn,
        'second_stage_localization_loss_weight': second_stage_localization_loss_weight,
        'second_stage_classification_loss': second_stage_classification_loss,
        'second_stage_classification_loss_weight': second_stage_classification_loss_weight,
        'hard_example_miner': hard_example_miner,
        'add_summaries': add_summaries}
  
    if isinstance(second_stage_box_predictor, box_predictor.RfcnBoxPredictor):
      return rfcn_meta_arch.RFCNMetaArch(
          second_stage_rfcn_box_predictor=second_stage_box_predictor,
          **common_kwargs)
    else:
      return faster_rcnn_meta_arch.FasterRCNNMetaArch(
          initial_crop_size=initial_crop_size,
          maxpool_kernel_size=maxpool_kernel_size,
          maxpool_stride=maxpool_stride,
          second_stage_mask_rcnn_box_predictor=second_stage_box_predictor,
          second_stage_mask_prediction_loss_weight=(
              second_stage_mask_prediction_loss_weight),
          **common_kwargs)
  