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Real-time YOLO object detection using reCamera based on Cpp

This document demonstrates how to implement real-time photo capture, YOLO object detection, and result access by HTTP with C++ based on cross-compilation on reCamera terminals. This approach avoids the overheating issues encountered when using Node-RED on reCamera. You can refer to this document to modify the C++ code for customized computer vision applications.

Environment Preparation​

Pre-compilation​

First, you need to refer to the "Develop with C/C++" document to configure the cross-compilation environment on your linux. Note: Reconfigure the path after each boot:

export SG200X_SDK_PATH=$HOME/recamera/sg2002_recamera_emmc/
export PATH=$HOME/recamera/host-tools/gcc/riscv64-linux-musl-x86_64/bin:$PATH

Then,enter the Realtime_detection_http folder under sscma-example-sg200x/solutions/, and compile it.​

cd sscma-example-sg200x/solutions/Realtime_detection_http/
mkdir build && cd build
cmake ..
make

The presence of the green executable file Realtime_detection_http in the build directory indicates successful compilation:

Then open the reCamera terminal, and copy the executable file to the reCamera terminal directory.​

 sudo scp Realtime_detection_http [email protected]:/home/recamera/

ReCamera Preparation​

1.Download the YOLOv11 which has been deployed from On Device Models, then copy the model's .cvimodel file to your reCamera terminal:/home/recamera/. 2.Before executing the code, please access the reCamera workspace to terminate the process (refer to Develop with c/c++) to prevent memory consumption. 3.Then navigate to /etc/init.d/, copy both the S93sscma-supervisor and S91sscma-node folders to /home/recamera/ or another location for backup, and delete the original S93sscma-supervisor and S91sscma-node folders to prevent memory consumption and program occupation.​

cd /etc/init.d/
sudo scp S93sscma-supervisor /home/recamera/
sudo scp S91sscma-node /home/recamera/
sudo rm -r S93sscma-supervisor
sudo rm -r S91sscma-node

Run the program​

Run the program as administrator under the /home/recamera/ on the reCamera terminal​:

sudo ./Realtime_detection_http

Results​

The terminal displays the following, indicating normal program operation:

You can access http://192.168.42.1/modeldetector via web browser or Postman.The reCamera will immediately capture a photo and return objects detected by YOLOv11.​ Browser:

Postman:

The returned information includes the following data:​​

  • Code:1 (Running)
  • Msg: Error messages
  • Initialize_camera_duration:Camera initialization duration is displayed only during the first access.​
  • Initialize_model_duration:Model initialization duration is displayed only during the first access.​
  • Data:
    • ​Score: Detection confidence score (0-1)
    • Target: Name of detected object
    • Box:[x1, y1, x2, y2]​: Detection box coordinates (in pixels representing [left, top, right, bottom] edges)
    • ​Center:[x, y]​: Normalized center position of the detection box (ratio relative to image width/height)
    • ​Size:[w, h]​: Normalized width and height of the detection box (ratio relative to image dimensions)
    • Release_duration: Time taken to clear camera cache (ms)
    • ​Capture_duration: Image acquisition duration (ms)
    • ​Image_preprocessing_duration: Image preparation before inference duration (ms)
    • Detection_duration: Model detection duration (ms) (Including Preprocessing,Inference,Postprocessing)
  • ​Duration: Total program execution time (ms)
  • Timestamp: Unix timestamp

The terminal will display:​

  • Camera initialization parameters​:
    • Resolution: 1920×1080
    • Frame rate: 5 fps
    • Capture channel: Channel 2
  • Captured image size (e.g. Jpeg size: 216149 (pixels))
  • ​Memory usage (MB) during different steps：
    • Pre-capture (Memory usage)
    • Releasing (Memory usageduring)
    • Post-capture (Memory usage_after)
    • After image preprocessing (Memory usage_before_model)
    • After model detection (Memory usage_after_model)
  • Model detection duration (ms)
    • Preprocessing (e.g.pre: 9ms)
    • Inference (e.g.infer: 40ms)
    • Postprocessing (e.g.post:395ms)

On the reCamera terminal, detected images can be automatically saved:​

You can continuously access it with your device to obtain real-time detection results for applications such as intelligent security and surveillance.

You can modify the returned message's format in registerModelDetector() (Realtime_detection_http/src/http.cpp) and model_detector() (Realtime_detection_http/src/model_detector.cpp). You can also use your own deployed model when calling the initialize_model(const std::string& model_path) in registerModelDetector(), and modify the camera initialization settings in initialize_camera()(Realtime_detection_http/src/model_detector.cpp):

After detection, you can press Ctrl+C to terminate the operation.​The program will stop the camera.​

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