【问题标题】:Tensorflow object detection API: Custom VGG 16 modelTensorflow 对象检测 API:自定义 VGG 16 模型
【发布时间】:2018-12-01 00:01:10
【问题描述】:

我正在创建一个自定义 VGG 模型作为 Tensorflow 对象检测 API 中 Faster RCNN 模型的特征提取器。如文档https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/defining_your_own_model.md 中所述,特征提取器代码由extract_proposal_featuresextract_classifier_features 组成。我正在使用创建卷积层的 TF slim 代码(因为 Tensorflow 团队使用它)。 TF slim使用返回的VGG 16的模型结构作为参考

      ([('vgg_16/conv1/conv1_1',
         <tf.Tensor 'vgg_16/vgg_16/conv1/conv1_1/Relu:0' shape=(?, 224, 224, 64) dtype=float32>),
        ('vgg_16/conv1/conv1_2',
         <tf.Tensor 'vgg_16/vgg_16/conv1/conv1_2/Relu:0' shape=(?, 224, 224, 64) dtype=float32>),
        ('vgg_16/vgg_16/pool1',
         <tf.Tensor 'vgg_16/vgg_16/pool1/MaxPool:0' shape=(?, 112, 112, 64) dtype=float32>),
        ('vgg_16/conv2/conv2_1',
         <tf.Tensor 'vgg_16/vgg_16/conv2/conv2_1/Relu:0' shape=(?, 112, 112, 128) dtype=float32>),
        ('vgg_16/conv2/conv2_2',
         <tf.Tensor 'vgg_16/vgg_16/conv2/conv2_2/Relu:0' shape=(?, 112, 112, 128) dtype=float32>),
        ('vgg_16/vgg_16/pool2',
         <tf.Tensor 'vgg_16/vgg_16/pool2/MaxPool:0' shape=(?, 56, 56, 128) dtype=float32>),
        ('vgg_16/conv3/conv3_1',
         <tf.Tensor 'vgg_16/vgg_16/conv3/conv3_1/Relu:0' shape=(?, 56, 56, 256) dtype=float32>),
        ('vgg_16/conv3/conv3_2',
         <tf.Tensor 'vgg_16/vgg_16/conv3/conv3_2/Relu:0' shape=(?, 56, 56, 256) dtype=float32>),
        ('vgg_16/conv3/conv3_3',
         <tf.Tensor 'vgg_16/vgg_16/conv3/conv3_3/Relu:0' shape=(?, 56, 56, 256) dtype=float32>),
        ('vgg_16/vgg_16/pool3',
         <tf.Tensor 'vgg_16/vgg_16/pool3/MaxPool:0' shape=(?, 28, 28, 256) dtype=float32>),
        ('vgg_16/conv4/conv4_1',
         <tf.Tensor 'vgg_16/vgg_16/conv4/conv4_1/Relu:0' shape=(?, 28, 28, 512) dtype=float32>),
        ('vgg_16/conv4/conv4_2',
         <tf.Tensor 'vgg_16/vgg_16/conv4/conv4_2/Relu:0' shape=(?, 28, 28, 512) dtype=float32>),
        ('vgg_16/conv4/conv4_3',
         <tf.Tensor 'vgg_16/vgg_16/conv4/conv4_3/Relu:0' shape=(?, 28, 28, 512) dtype=float32>),
        ('vgg_16/vgg_16/pool4',
         <tf.Tensor 'vgg_16/vgg_16/pool4/MaxPool:0' shape=(?, 14, 14, 512) dtype=float32>),
        ('vgg_16/conv5/conv5_1',
         <tf.Tensor 'vgg_16/vgg_16/conv5/conv5_1/Relu:0' shape=(?, 14, 14, 512) dtype=float32>),
        ('vgg_16/conv5/conv5_2',
         <tf.Tensor 'vgg_16/vgg_16/conv5/conv5_2/Relu:0' shape=(?, 14, 14, 512) dtype=float32>),
        ('vgg_16/conv5/conv5_3',
         <tf.Tensor 'vgg_16/vgg_16/conv5/conv5_3/Relu:0' shape=(?, 14, 14, 512) dtype=float32>),
        ('vgg_16/vgg_16/pool5',
         <tf.Tensor 'vgg_16/vgg_16/pool5/MaxPool:0' shape=(?, 7, 7, 512) dtype=float32>),
        ('vgg_16/fc6',
         <tf.Tensor 'vgg_16/vgg_16/fc6/Relu:0' shape=(?, 1, 1, 4096) dtype=float32>),
        ('vgg_16/fc7',
         <tf.Tensor 'vgg_16/vgg_16/fc7/Relu:0' shape=(?, 1, 1, 4096) dtype=float32>)])

我的问题是,extract_proposal_features 方法中需要包含并返回哪些卷积层,extract_classifier_features 中需要包含并返回哪些卷积层。请告诉我。

【问题讨论】:

    标签: python tensorflow tensorflow-slim vgg-net


    【解决方案1】:

    这是寻求 SSD 架构的额外答案,Tensorflow 对象检测 API 1 包含来自 slim 文件夹的 vgg 架构,我们可以直接导入它 from nets import vgg。我刚刚尝试过使用 SSD 架构。我按照 ssd-mobilenet 配置从 2 层“fc7”和“conv4_3”创建各自的模型,如 paper 中所述。然后,将新的SSD-VGG16_feature_extractor.py 保存在models 文件夹中。

    注意为了与paper中的vgg正确匹配,您应该将4096更改为1024,将内核大小[7,7]更改为[3,3]以获得正确的深度特征https://github.com/tensorflow/models/blob/master/research/slim/nets/vgg.py#L206-L209

    import tensorflow.compat.v1 as tf
    import tf_slim as slim
    
    from object_detection.meta_architectures import ssd_meta_arch
    from object_detection.models import feature_map_generators
    from object_detection.utils import ops
    from object_detection.utils import shape_utils
    from nets import vgg
    
    
    class SSDVgg16FeatureExtractor(ssd_meta_arch.SSDFeatureExtractor):
      """SSD Feature Extractor using Vgg16 features."""
    
      def __init__(self,
                   is_training,
                   depth_multiplier,
                   min_depth,
                   pad_to_multiple,
                   conv_hyperparams_fn,
                   reuse_weights=None,
                   use_explicit_padding=False,
                   use_depthwise=False,
                   override_base_feature_extractor_hyperparams=False):
        """Vgg16 Feature Extractor for SSD Models.
        Args:
          is_training: whether the network is in training mode.
          depth_multiplier: float depth multiplier for feature extractor.
          min_depth: minimum feature extractor depth.
          pad_to_multiple: the nearest multiple to zero pad the input height and
            width dimensions to.
          conv_hyperparams_fn: A function to construct tf slim arg_scope for conv2d
            and separable_conv2d ops in the layers that are added on top of the
            base feature extractor.
          reuse_weights: Whether to reuse variables. Default is None.
          use_explicit_padding: Whether to use explicit padding when extracting
            features. Default is False.
          use_depthwise: Whether to use depthwise convolutions. Default is False.
          num_layers: Number of SSD layers.
          override_base_feature_extractor_hyperparams: Whether to override
            hyperparameters of the base feature extractor with the one from
            `conv_hyperparams_fn`.
        Raises:
          ValueError: If `override_base_feature_extractor_hyperparams` is False.
        """
        super(SSDVgg16FeatureExtractor, self).__init__(
            is_training=is_training,
            depth_multiplier=depth_multiplier,
            min_depth=min_depth,
            pad_to_multiple=pad_to_multiple,
            conv_hyperparams_fn=conv_hyperparams_fn,
            reuse_weights=reuse_weights,
            use_explicit_padding=use_explicit_padding,
            use_depthwise=use_depthwise,
            override_base_feature_extractor_hyperparams=
            override_base_feature_extractor_hyperparams)
        if not self._override_base_feature_extractor_hyperparams:
          raise ValueError('SSD Vgg16 feature extractor always uses'
                           'scope returned by `conv_hyperparams_fn` for both the '
                           'base feature extractor and the additional layers '
                           'added since there is no arg_scope defined for the base '
                           'feature extractor.')
    
      def preprocess(self, resized_inputs):
        """SSD preprocessing.
        Maps pixel values to the range [-1, 1].
        Args:
          resized_inputs: a [batch, height, width, channels] float tensor
            representing a batch of images.
        Returns:
          preprocessed_inputs: a [batch, height, width, channels] float tensor
            representing a batch of images.
        """
        return (2.0 / 255.0) * resized_inputs - 1.0
    
      def extract_features(self, preprocessed_inputs):
        """Extract features from preprocessed inputs.
        Args:
          preprocessed_inputs: a [batch, height, width, channels] float tensor
            representing a batch of images.
        Returns:
          feature_maps: a list of tensors where the ith tensor has shape
            [batch, height_i, width_i, depth_i]
        """
        preprocessed_inputs = shape_utils.check_min_image_dim(
            33, preprocessed_inputs)
    
        feature_map_layout = {
            'from_layer': ['FeatureExtractor/vgg_16/conv4/conv4_3', 'FeatureExtractor/vgg_16/fc7', '', '', '', ''],
            'layer_depth': [-1, -1, 512, 256, 256, 128],
            'use_explicit_padding': self._use_explicit_padding,
            'use_depthwise': self._use_depthwise,
        }
        with slim.arg_scope(self._conv_hyperparams_fn()):
          with slim.arg_scope(vgg.vgg_arg_scope()):
            _, image_features = vgg.vgg_16(
                ops.pad_to_multiple(preprocessed_inputs, self._pad_to_multiple),
                num_classes=0)
        print("Available output head: ")
        print([k for k,v in image_features.items()])
        with slim.arg_scope(self._conv_hyperparams_fn()):
          feature_maps = feature_map_generators.multi_resolution_feature_maps(
            feature_map_layout=feature_map_layout,
            depth_multiplier=self._depth_multiplier,
            min_depth=self._min_depth,
            insert_1x1_conv=True,
            image_features=image_features)
    
        return list(feature_maps.values())
    

    然后,你只需要更新SSD_FEATURE_EXTRACTOR_CLASS_MAP中的'ssd_vgg16': SSDVgg16FeatureExtractorbuilder/model_builder.py中的dict即可完成模型。

    我已经测试过,它就像魅力一样工作

    INFO:tensorflow:global_step/sec: 0.195851
    I1223 18:19:21.963316 139974845604416 basic_session_run_hooks.py:692] global_step/sec: 0.195851
    INFO:tensorflow:loss = 3.674446, step = 700 (510.592 sec)
    I1223 18:19:21.964789 139974845604416 basic_session_run_hooks.py:260] loss = 3.674446, step = 700 (510.592 sec)
    

    【讨论】:

      【解决方案2】:

      我已更改 vgg slim 代码以获得正确的张量。

      def vgg_16(inputs,
             num_classes=1000,
             is_training=True,
             dropout_keep_prob=0.5,
             spatial_squeeze=True,
             scope='vgg_16',
             fc_conv_padding='VALID',
             global_pool=False):
      """Oxford Net VGG 16-Layers version D Example.
      
      Note: All the fully_connected layers have been transformed to conv2d layers.
            To use in classification mode, resize input to 224x224.
      
      Args:
        inputs: a tensor of size [batch_size, height, width, channels].
        num_classes: number of predicted classes. If 0 or None, the logits layer is
          omitted and the input features to the logits layer are returned instead.
        is_training: whether or not the model is being trained.
        dropout_keep_prob: the probability that activations are kept in the dropout
          layers during training.
        spatial_squeeze: whether or not should squeeze the spatial dimensions of the
          outputs. Useful to remove unnecessary dimensions for classification.
        scope: Optional scope for the variables.
        fc_conv_padding: the type of padding to use for the fully connected layer
          that is implemented as a convolutional layer. Use 'SAME' padding if you
          are applying the network in a fully convolutional manner and want to
          get a prediction map downsampled by a factor of 32 as an output.
          Otherwise, the output prediction map will be (input / 32) - 6 in case of
          'VALID' padding.
        global_pool: Optional boolean flag. If True, the input to the classification
          layer is avgpooled to size 1x1, for any input size. (This is not part
          of the original VGG architecture.)
      
      Returns:
        net: the output of the logits layer (if num_classes is a non-zero integer),
          or the input to the logits layer (if num_classes is 0 or None).
        end_points: a dict of tensors with intermediate activations.
      """
      with tf.variable_scope(scope, 'vgg_16', [inputs]) as sc:
          end_points_collection = sc.original_name_scope + '_end_points'
          # Collect outputs for conv2d, fully_connected and max_pool2d.
          with slim.arg_scope([slim.conv2d, slim.fully_connected, slim.max_pool2d],
                              outputs_collections=end_points_collection):
              net = slim.repeat(inputs, 2, slim.conv2d, 64, [3, 3], scope='conv1')
              net = slim.max_pool2d(net, [2, 2], scope='pool1')
              net = slim.repeat(net, 2, slim.conv2d, 128, [3, 3], scope='conv2')
              net = slim.max_pool2d(net, [2, 2], scope='pool2')
              net = slim.repeat(net, 3, slim.conv2d, 256, [3, 3], scope='conv3')
              net = slim.max_pool2d(net, [2, 2], scope='pool3')
              net = slim.repeat(net, 3, slim.conv2d, 512, [3, 3], scope='conv4')
              net = slim.max_pool2d(net, [2, 2], scope='pool4')
              net = slim.repeat(net, 3, slim.conv2d, 512, [3, 3], scope='conv5')
              net = slim.max_pool2d(net, [2, 2], scope='pool5')
      
              # Convert end_points_collection into a end_point dict.
              end_points = slim.utils.convert_collection_to_dict(end_points_collection)
      
              end_points['head'] = net
      
              # Use conv2d instead of fully_connected layers.
              net = slim.conv2d(net, 4096, [7, 7], padding=fc_conv_padding, scope='fc6')
              net = slim.dropout(net, dropout_keep_prob, is_training=is_training,
                                 scope='dropout6')
              net = slim.conv2d(net, 4096, [1, 1], scope='fc7')
      
              if global_pool:
                  net = tf.reduce_mean(net, [1, 2], keep_dims=True, name='global_pool')
                  end_points['global_pool'] = net
              if num_classes:
                  net = slim.dropout(net, dropout_keep_prob, is_training=is_training,
                                     scope='dropout7')
                  net = slim.conv2d(net, num_classes, [1, 1],
                                    activation_fn=None,
                                    normalizer_fn=None,
                                    scope='fc8')
                  if spatial_squeeze and num_classes is not None:
                      net = tf.squeeze(net, [1, 2], name='fc8/squeezed')
                  end_points[sc.name + '/fc8'] = net
              return net, end_points
      

      end_points['head'] = net 是用于提取_proposal_features 的张量。

      def _extract_proposal_features(self, preprocessed_inputs, scope):
          """Extracts first stage RPN features.
      
          Args:
            preprocessed_inputs: A [batch, height, width, channels] float32 tensor
              representing a batch of images.
            scope: A scope name.
      
          Returns:
            rpn_feature_map: A tensor with shape [batch, height, width, depth]
          Raises:
            InvalidArgumentError: If the spatial size of `preprocessed_inputs`
              (height or width) is less than 33.
            ValueError: If the created network is missing the required activation.
          """
      
          preprocessed_inputs.get_shape().assert_has_rank(4)
          shape_assert = tf.Assert(
              tf.logical_and(tf.greater_equal(tf.shape(preprocessed_inputs)[1], 33),
                             tf.greater_equal(tf.shape(preprocessed_inputs)[2], 33)),
              ['image size must at least be 33 in both height and width.'])
      
          with tf.control_dependencies([shape_assert]):
              with tf.variable_scope('vgg_16', 'vgg_16', reuse=self._reuse_weights):
                  _, activations = vgg.vgg_16(
                      preprocessed_inputs,
                      scope=scope)
      
          return activations['head']
      

      def _extract_box_classifier_features(self, proposal_feature_maps, scope):
          """Extracts second stage box classifier features.
      
          Args:
            proposal_feature_maps: A 4-D float tensor with shape
              [batch_size * self.max_num_proposals, crop_height, crop_width, depth]
              representing the feature map cropped to each proposal.
            scope: A scope name (unused).
      
          Returns:
            proposal_classifier_features: A 4-D float tensor with shape
              [batch_size * self.max_num_proposals, height, width, depth]
              representing box classifier features for each proposal.
          """
          net = proposal_feature_maps
      
          with tf.variable_scope('vgg_16', reuse=self._reuse_weights):
              with slim.arg_scope(
                      [slim.conv2d],
                      stride=1,
                      padding='VALID'):
                  # Use conv2d instead of fully_connected layers.
                  fc6 = slim.conv2d(net, 4096, [7, 7], padding='VALID', scope='fc6')
                  if self._is_training:
                      fc6 = slim.dropout(fc6, keep_prob=0.5, is_training=True,
                                         scope='dropout6')
                  fc7 = slim.conv2d(fc6, 4096, [1, 1], scope='fc7')
                  if self._is_training:
                      fc7 = slim.dropout(fc7, keep_prob=0.5, is_training=True,
                                         scope='dropout7')
          proposal_classifier_features = fc7
      
          return proposal_classifier_features
      

      我喜欢这样。我不知道这是否正确:)

      这是我的测试代码。

      import numpy as np
      import tensorflow as tf
      
      from models import faster_rcnn_vgg_16_feature_extractor as faster_rcnn_vgg_16
      
      
      class FasterRcnnVgg16FeatureExtractorTest(tf.test.TestCase):
      
      def _build_feature_extractor(self, first_stage_features_stride):
          return faster_rcnn_vgg_16.FasterRCNNVgg16FeatureExtractor(
              is_training=False,
              first_stage_features_stride=first_stage_features_stride,
              weight_decay=0.0005)
      
      def test_extract_proposal_features_returns_expected_size(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=16)
          preprocessed_inputs = tf.random_uniform(
              [4, 224, 224, 3], maxval=255, dtype=tf.float32)
          rpn_feature_map = feature_extractor.extract_proposal_features(
              preprocessed_inputs, scope='TestScope')
          features_shape = tf.shape(rpn_feature_map)
      
          init_op = tf.global_variables_initializer()
          with self.test_session() as sess:
              sess.run(init_op)
              features_shape_out = sess.run(features_shape)
              self.assertAllEqual(features_shape_out, [4, 7, 7, 512])
      
      def test_extract_proposal_features_stride_eight(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=8)
          preprocessed_inputs = tf.random_uniform(
              [4, 224, 224, 3], maxval=255, dtype=tf.float32)
          rpn_feature_map = feature_extractor.extract_proposal_features(
              preprocessed_inputs, scope='TestScope')
          features_shape = tf.shape(rpn_feature_map)
      
          init_op = tf.global_variables_initializer()
          with self.test_session() as sess:
              sess.run(init_op)
              features_shape_out = sess.run(features_shape)
              self.assertAllEqual(features_shape_out, [4, 7, 7, 512])
      
      def test_extract_proposal_features_half_size_input(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=16)
          preprocessed_inputs = tf.random_uniform(
              [1, 112, 112, 3], maxval=255, dtype=tf.float32)
          rpn_feature_map = feature_extractor.extract_proposal_features(
              preprocessed_inputs, scope='TestScope')
          features_shape = tf.shape(rpn_feature_map)
      
          init_op = tf.global_variables_initializer()
          with self.test_session() as sess:
              sess.run(init_op)
              features_shape_out = sess.run(features_shape)
              self.assertAllEqual(features_shape_out, [1, 4, 4, 512])
      
      def test_extract_proposal_features_dies_on_invalid_stride(self):
          with self.assertRaises(ValueError):
              self._build_feature_extractor(first_stage_features_stride=99)
      
      def test_extract_proposal_features_dies_on_very_small_images(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=16)
          preprocessed_inputs = tf.placeholder(tf.float32, (4, None, None, 3))
          rpn_feature_map = feature_extractor.extract_proposal_features(
              preprocessed_inputs, scope='TestScope')
          features_shape = tf.shape(rpn_feature_map)
      
          init_op = tf.global_variables_initializer()
          with self.test_session() as sess:
              sess.run(init_op)
              with self.assertRaises(tf.errors.InvalidArgumentError):
                  sess.run(
                      features_shape,
                      feed_dict={preprocessed_inputs: np.random.rand(4, 32, 32, 3)})
      
      def test_extract_proposal_features_dies_with_incorrect_rank_inputs(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=16)
          preprocessed_inputs = tf.random_uniform(
              [224, 224, 3], maxval=255, dtype=tf.float32)
          with self.assertRaises(ValueError):
              feature_extractor.extract_proposal_features(
                  preprocessed_inputs, scope='TestScope')
      
      def test_extract_box_classifier_features_returns_expected_size(self):
          feature_extractor = self._build_feature_extractor(
              first_stage_features_stride=16)
          proposal_feature_maps = tf.random_uniform(
              [3, 7, 7, 512], maxval=255, dtype=tf.float32)
          proposal_classifier_features = (
              feature_extractor.extract_box_classifier_features(
                  proposal_feature_maps, scope='TestScope'))
          features_shape = tf.shape(proposal_classifier_features)
      
          init_op = tf.global_variables_initializer()
          with self.test_session() as sess:
              sess.run(init_op)
              features_shape_out = sess.run(features_shape)
              self.assertAllEqual(features_shape_out, [3, 1, 1, 4096])
      
      
      if __name__ == '__main__':
            tf.test.main()
      

      【讨论】:

      • 嗨,里奇。我做了同样的事情。但是在_extract_box_classifier_features 方法中,提案分类器 features = fc 7 抛出了一个错误,指出全局池不能在全连接层旁边使用。你有没有遇到这个。所以我实际上替换了代码。
      • 我在 openimages 上训练了模型,没有出现错误。我使用了张量流 1.4.1。预训练的 vgg16 来自 slim vgg_16_2016_08_28.tar.gz。我失去了我的训练评估,所以我不能发布图片。我需要修改 api 中的其他 python 文件以使其工作(否则 api 看不到新模型)。
      • 是的,里奇。谢谢你的cmets。你用了什么元架构师,1.SSD 2.FastRCNN 3. FasterRCNN。我尝试使用 FasterRCNN,但它给了我一个错误。所以我删除了 FCNN,只保留了特征提取器的 CNN 部分。
      • 我使用了 Faster R-CCN​​。我将测试类添加到答案中。
      • 从您的测试课程中,我可以看到我的模式元架构不同。感谢您的分享。 :)
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