Face Analysis Pipeline

Analyze Multiple Faces in a Single Image Frame

This guide demonstrates how to create complex pipelines using object detection and object recognition models from Open Model Zoo. In this example, we use the face-detection-retail-0004 model to detect multiple faces in an image. Next, for each detected face we crop using the model_zoo_intel_object_detection custom node sample. Finally, each cropped image containing a face is sent to the age-gender-recognition-retail-0013 and emotion-recognition-retail-0003 models.

Faces analysis graph

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

Pipeline Configuration Graph

Below is depicted graph implementing faces analysis pipeline execution.

Faces Analysis Pipeline Graph

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.

Prepare the models from OpenVINO Model Zoo

Face detection model

wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/age-gender-recognition-retail-0013/FP32/age-gender-recognition-retail-0013.xml
wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/age-gender-recognition-retail-0013/FP32/age-gender-recognition-retail-0013.bin

Age gender recognition model

wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/face-detection-retail-0004/FP32/face-detection-retail-0004.xml
wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/face-detection-retail-0004/FP32/face-detection-retail-0004.bin

Emotions recognition model

wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/emotions-recognition-retail-0003/FP32/emotions-recognition-retail-0003.xml
wget https://storage.openvinotoolkit.org/repositories/open_model_zoo/2021.3/models_bin/2/emotions-recognition-retail-0003/FP32/emotions-recognition-retail-0003.bin

Building the Custom Node “model_zoo_intel_object_detection” Library

Custom nodes are loaded into OVMS as dynamic libraries implementing OVMS API from custom_node_interface.h. It can use OpenCV libraries included in OVMS or it could use other thirdparty components.

The custom node model_zoo_intel_object_detection can be built inside a docker container via the following procedure:

This command will export the compiled library in ./lib folder. Copy this lib folder to the same location with previously downloaded models.

OVMS Configuration File

The configuration file for running the faces analysis demo is stored in config.json. Copy this file along with the model files.

Final directory structure

├── 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

Deploying OVMS

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

Requesting the Service

Exemplary client faces_analysis_pipeline_client.py can be used to request pipeline deployed in previous step.

From the context of example_client folder install python3 requirements:

pip install -r client_requirements.txt

Now you can create a directory for text images and run the client:

mkdir results
python3 faces_analysis_pipeline_client.py --pipeline_name find_face_images --grpc_port 9000 --image_input_path ./images/people/people1.jpeg --face_images_output_name face_images --face_images_save_path ./results --image_width 600 --image_height 400 --input_image_layout NHWC
Output: name[genders]
    numpy => shape[(10, 1, 2, 1, 1)] data[float32]
Output: name[ages]
    numpy => shape[(10, 1, 1, 1, 1)] data[float32]
Output: name[face_images]
    numpy => shape[(10, 1, 3, 64, 64)] data[float32]
Output: name[confidence_levels]
    numpy => shape[(10, 1, 1)] data[float32]
Output: name[face_coordinates]
    numpy => shape[(10, 1, 4)] data[float32]
Output: name[emotions]
    numpy => shape[(10, 1, 5, 1, 1)] data[float32]

Found 10 faces:
Age: 36 ; Gender: male ; Emotion: happy ; Original image coordinate: [0.5524015  0.3024714  0.5912314  0.39167267]
Age: 24 ; Gender: male ; Emotion: neutral ; Original image coordinate: [0.33651015 0.6238419  0.38452235 0.7109271 ]
Age: 22 ; Gender: male ; Emotion: happy ; Original image coordinate: [0.2273316  0.34603435 0.26951137 0.44243896]
Age: 46 ; Gender: male ; Emotion: happy ; Original image coordinate: [0.44218776 0.29372305 0.48234263 0.3778239 ]
Age: 41 ; Gender: female ; Emotion: happy ; Original image coordinate: [0.51707435 0.5602793  0.56729674 0.65029866]
Age: 26 ; Gender: male ; Emotion: happy ; Original image coordinate: [0.79853094 0.35693872 0.8411772  0.42878723]
Age: 26 ; Gender: female ; Emotion: happy ; Original image coordinate: [0.6506455  0.5917437  0.69963944 0.6924231 ]
Age: 30 ; Gender: male ; Emotion: happy ; Original image coordinate: [0.67255247 0.32400367 0.72031224 0.41411582]
Age: 22 ; Gender: female ; Emotion: happy ; Original image coordinate: [0.13879137 0.3621901  0.18784638 0.45262757]
Age: 22 ; Gender: female ; Emotion: happy ; Original image coordinate: [0.33016038 0.37727407 0.36954236 0.44583443]

With additional parameter --face_images_save_path the client script saves all detected text images to jpeg files into directory path to confirm if the image was analyzed correctly.