This document demonstrates how to create complex pipelines using object detection and object recognition models from OpenVINO Model Zoo. As an example, we will use face-detection-retail-0004 to detect multiple faces on the image. Then, for each detected face we will crop it using model_zoo_intel_object_detection example custom node. Finally, each image face image will be forwarded to age-gender-recognition-retail-0013 and emotion-recognition-retail-0003 models.

Using such a pipeline, a single request to OVMS can perform a complex set of operations to determine all faces and their properties.

For simpler use case with single face analysis see single_face_analysis_pipeline demo.

Below is depicted graph implementing faces analysis pipeline execution.

It includes the following Nodes:

• Model face-detection - deep learning model which takes user image as input. Its outputs contain information about face coordinates and confidence levels.
• Custom node model_zoo_intel_object_detection - it includes C++ implementation of common object detection models results processing. By analysing the output it produces cropped face images based on the configurable score level threshold. Custom node also resizes them to the target resolution and combines into a single output of a dynamic batch size. The output batch size is determined by the number of detected boxes according to the configured criteria. All operations on the images employ OpenCV libraries which are preinstalled in the OVMS. Learn more about the model_zoo_intel_object_detection custom node.
• demultiplexer - outputs from the custom node model_zoo_intel_object_detection have variable batch size. In order to match it with the sequential recognition models, data is split into individuial images with each batch size equal to 1. Such smaller requests can be submitted for inference in parallel to the next Model Nodes. Learn more about the demultiplexing.
• Model age-gender-recognition - this model recognizes age and gender on given face image
• Model emotion-recognition - this model outputs emotion probability for emotions: neutral, happy, sad, surprised and angry
• Response - the output of the whole pipeline combines the recognized face images with their metadata: coordinates, age, gender, emotions and detection confidence level.

To successfully deploy face analysis pipeline you need to have a workspace that contains:

• face-detection-retail-0004, age-gender-recognition-retail-0013 and emotion-recognition-retail-0003 models
• Custom node for image processing
• Configuration file

Clone the repository and enter multi_faces_analysis_pipeline directory

git clone https://github.com/openvinotoolkit/model_server.git
cd model_server/demos/multi_faces_analysis_pipeline/python

You can prepare the workspace that contains all the above by just running

make

Once the make procedure is finished, you should have workspace directory ready with the following content.

workspace
├── age-gender-recognition-retail-0013
│   └── 1
│       ├── age-gender-recognition-retail-0013.bin
│       └── age-gender-recognition-retail-0013.xml
├── config.json
├── emotion-recognition-retail-0003
│   └── 1
│       ├── emotions-recognition-retail-0003.bin
│       └── emotions-recognition-retail-0003.xml
├── face-detection-retail-0004
│   └── 1
│       ├── face-detection-retail-0004.bin
│       └── face-detection-retail-0004.xml
└── lib
    └── libcustom_node_model_zoo_intel_object_detection.so

Deploy OVMS with faces analysis pipeline using the following command:

docker run -p 9000:9000 -d -v ${PWD}/workspace:/workspace openvino/model_server --config_path /workspace/config.json --port 9000

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