Notes on Caffe layers

最新推荐文章于 2020-06-03 11:46:06 发布

原创最新推荐文章于 2020-06-03 11:46:06 发布 · 800 阅读

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本文详细介绍了Caffe中如何加载层的过程，包括通过LayerParameter从注册表中创建层的具体实现，以及层如何声明其类型和输入输出Blob的数量。此外还讲解了层设置过程中对Blob数量进行检查的方法。

How caffe load a layer

The main codes are in caffe::Net::Init()

const LayerParameter& layer_param = param.layer(layer_id);
...
layers_.push_back(LayerRegistry<Dtype>::CreateLayer(layer_param));

Then the layer is created by look up from the registry table:

  // Get a layer using a LayerParameter.
  static shared_ptr<Layer<Dtype> > CreateLayer(const LayerParameter& param) {
    if (Caffe::root_solver()) {
      LOG(INFO) << "Creating layer " << param.name();
    }
    const string& type = param.type();
    CreatorRegistry& registry = Registry();
    CHECK_EQ(registry.count(type), 1) << "Unknown layer type: " << type
        << " (known types: " << LayerTypeListString() << ")";
    return registry[type](param);
  }

Still not understand

relative with parallelism.

    if (share_from_root) {
      LOG(INFO) << "Sharing layer " << layer_param.name() << " from root net";
      layers_.push_back(root_net_->layers_[layer_id]);
      layers_[layer_id]->SetShared(true);
    }

Several *Blobs() function

Relative PR:

Layers declare their types and number of bottom/top blobs #479

Called from caffe::Layer::SetUp():

  void SetUp(const vector<Blob<Dtype>*>& bottom,
      const vector<Blob<Dtype>*>& top) {
    InitMutex();
    CheckBlobCounts(bottom, top); // virtual
    LayerSetUp(bottom, top); // virtual
    Reshape(bottom, top); // virtual
    SetLossWeights(top);
  }

by CheckBlobCounts(bottom, top), which is a virtual function may be overrided in the inherited layer class. Following is the function of the base layer, caffe::Layer::CheckBlobCounts():

  /**
   * Called by the parent Layer's SetUp to check that the number of bottom
   * and top Blobs provided as input match the expected numbers specified by
   * the {ExactNum,Min,Max}{Bottom,Top}Blobs() functions.
   */
  virtual void CheckBlobCounts(const vector<Blob<Dtype>*>& bottom,
                               const vector<Blob<Dtype>*>& top) {
    if (ExactNumBottomBlobs() >= 0) {
      CHECK_EQ(ExactNumBottomBlobs(), bottom.size())
          << type() << " Layer takes " << ExactNumBottomBlobs()
          << " bottom blob(s) as input.";
    }
    if (MinBottomBlobs() >= 0) {
      CHECK_LE(MinBottomBlobs(), bottom.size())
          << type() << " Layer takes at least " << MinBottomBlobs()
          << " bottom blob(s) as input.";
    }
    if (MaxBottomBlobs() >= 0) {
      CHECK_GE(MaxBottomBlobs(), bottom.size())
          << type() << " Layer takes at most " << MaxBottomBlobs()
          << " bottom blob(s) as input.";
    }
    if (ExactNumTopBlobs() >= 0) {
      CHECK_EQ(ExactNumTopBlobs(), top.size())
          << type() << " Layer produces " << ExactNumTopBlobs()
          << " top blob(s) as output.";
    }
    if (MinTopBlobs() >= 0) {
      CHECK_LE(MinTopBlobs(), top.size())
          << type() << " Layer produces at least " << MinTopBlobs()
          << " top blob(s) as output.";
    }
    if (MaxTopBlobs() >= 0) {
      CHECK_GE(MaxTopBlobs(), top.size())
          << type() << " Layer produces at most " << MaxTopBlobs()
          << " top blob(s) as output.";
    }
    if (EqualNumBottomTopBlobs()) {
      CHECK_EQ(bottom.size(), top.size())
          << type() << " Layer produces one top blob as output for each "
          << "bottom blob input.";
    }
  }