EXPORT_ONNX_MODEL_en.md

# PaddleDetection Model Export as ONNX Format Tutorial

PaddleDetection Model support is saved in ONNX format and the list of current test support is as follows
| Model  | OP Version | NOTE |
| :---- | :----- | :--- |
| YOLOv3 |  11   |  Only batch=1 inferring is supported. Model export needs fixed shape |
| PPYOLO | 11 | Only batch=1 inferring is supported. A MatrixNMS will be converted to an NMS with slightly different precision; Model export needs fixed shape |
| PPYOLOv2 | 11 | Only batch=1 inferring is supported. MatrixNMS will be converted to NMS with slightly different precision; Model export needs fixed shape |
| PPYOLO-Tiny | 11 | Only batch=1 inferring is supported. Model export needs fixed shape |
| FCOS | 11 |Only batch=1 inferring is supported |
| PAFNet | 11 |- |
| TTFNet | 11 |-|
| SSD | 11 |Only batch=1 inferring is supported |

The function of saving ONNX is provided by [Paddle2ONNX](https://github.com/PaddlePaddle/Paddle2ONNX). If there is feedback on related problems during conversion, Communicate with engineers in Paddle2ONNX's Github project via [ISSUE](https://github.com/PaddlePaddle/Paddle2ONNX/issues).

## Export Tutorial

### Step 1. Export the Paddle deployment model
Export procedure reference document[Tutorial on PaddleDetection deployment model export](./EXPORT_MODEL_en.md), take YOLOv3 of COCO dataset training as an example
```
cd PaddleDetection
python tools/export_model.py -c configs/yolov3/yolov3_darknet53_270e_coco.yml \
                             -o weights=https://paddledet.bj.bcebos.com/models/yolov3_darknet53_270e_coco.pdparams \
                             TestReader.inputs_def.image_shape=[3,608,608] \
                             --output_dir inference_model
```
The derived models were saved in `inference_model/yolov3_darknet53_270e_coco/`, with the structure as follows
```
yolov3_darknet
  ├── infer_cfg.yml          # Model configuration file information
  ├── model.pdiparams        # Static diagram model parameters
  ├── model.pdiparams.info   # Parameter Information is not required
  └── model.pdmodel          # Static diagram model file
```
> check`TestReader.inputs_def.image_shape`, For YOLO series models, specify this parameter when exporting; otherwise, the conversion fails

### Step 2. Convert the deployment model to ONNX format
Install Paddle2ONNX (version 0.6 or higher)
```
pip install paddle2onnx
```
Use the following command to convert
```
paddle2onnx --model_dir inference_model/yolov3_darknet53_270e_coco \
            --model_filename model.pdmodel \
            --params_filename model.pdiparams \
            --opset_version 11 \
            --save_file yolov3.onnx
```
The transformed model is under the current path`yolov3.onnx`