6f0aaf2bb5
* First draft of nGraph documentation * updated according to review comments * Updated * Reviewed the nGraph Transformation section, added missing images * Update nGraph_dg.md * Delete python_api.md Removed since there is already the nGraph_Python_API.md document with a comprehensive overview. * Fixed links to images Co-authored-by: Andrey Zaytsev <andrey.zaytsev@intel.com> Co-authored-by: CCR\avladimi <anastasiya.ageeva@intel.com>
47 lines
2.9 KiB
Markdown
47 lines
2.9 KiB
Markdown
# Introduction to the nGraph {#openvino_docs_nGraph_DG_Introduction}
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The Inference Engine integrates the nGraph to represent a model in run time underneath of the conventional
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`CNNNetwork` API, which is an instance of `ngraph::Function`.
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Besides the representation update, nGraph supports new features:
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1. nGraph contains several [sets of operations which are called `opset1`, `opset2` and etc.](../ops/opset.md).
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Operations from these operation sets are generated by the Model Optimizer and are accepted in the Inference Engine.
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2. Operation version is attached to each operation rather than to the entire IR file format.
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IR is still versioned but has a different meaning. For details, see [Deep Learning Network Intermediate Representation and Operation Sets in OpenVINO™](../MO_DG/IR_and_opsets.md).
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3. Creating models in run-time without loading IR from an xml/binary file. You can enable it by creating
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`ngraph::Function` passing it to `CNNNetwork`.
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4. Run-time reshape capability and constant folding are implemented through the nGraph code for more operations compared to previous releases.
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As a result, more models can be reshaped. For details, see the [dedicated guide about the reshape capability](../IE_DG/ShapeInference.md).
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5. Loading [model from ONNX format](../IE_DG/ONNX_Support.md) without converting it to the Inference Engine IR.
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6. nGraph representation supports dynamic shapes. You can use `CNNNetwork::reshape()` method in order to specialize input shapes.
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The complete picture of existed flow is presented below.
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## Read the Intermediate Representation to `CNNNetwork`
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The IR version 10 automatically triggers the nGraph flow inside the Inference Engine.
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When such IR is read in an application, the Inference Engine IR reader produces `CNNNetwork` that encapsulates the `ngraph::Function` instance underneath.
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Interpretation of the IR version 10 differs from the old IR version.
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Besides having a different operations set, the IR version 10 ignores the shapes and data types assigned to the ports in an XML file.
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Both shapes and types are reinferred while loading to the Inference Engine using the nGraph shape and type propagation function that is a part of each nGraph operation.
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## Build a Model in the Application
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Alternative method to feed the Inference Engine with a model is to create the model in the run time.
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It is achieved by creation of the `ngraph::Function` construction using nGraph operation classes and optionally user-defined operations.
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For details, see [Add Custom nGraph Operations](../IE_DG/Extensibility_DG/AddingNGraphOps.md) and [examples](build_function.md).
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At this stage, the code is completely independent of the rest of the Inference Engine code and can be built separately.
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After you construct an instance of `ngraph::Function`, you can use it to create `CNNNetwork` by passing it to the new constructor for this class.
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## See Also
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- [Available Operations Sets](../ops/opset.md)
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