This is a ROS 2 wrapper around darknet, an open source neural network framework.

This node can run object detectors like YOLO v3 or YOLO v7 on images and video streams.

• ~/images (type sensor_msgs/msg/Image) - Input mages to feed to the detector

• ~/detections (type vision_msgs/msg/Detection2DArray) - Objects detected in an image (if any)

• network.config - a path to a file describing a darknet detector network
• network.weights - a path to a file with weights for the given network
• network.class_names - a path to a file with names of classes the network can detect (1 per line)
• detection.threshold - Minimum probability of a detection to be published
• detection.nms_threshold - Non-maximal Suppression threshold - controls filtering of overlapping boxes

This package depends on darknet. If you can't use CUDA but want to use your CPU instead make sure to build it with the flag -DENABLE_CUDA=OFF and potentially also disabling multi-threading with -DCMAKE_DISABLE_FIND_PACKAGE_OpenMP=TRUE.

Compiling this package with

$ colcon build --cmake-args -DDOWNLOAD_YOLO_CONFIG=ON

will automatically download the pretrained YOLO v3, v4 and v7 configuration files.

You can then launch the detector node with

$ ros2 launch openrobotics_darknet_ros detector_launch.py rgb_image:=/topic

optionally supplying a desired parameter file detector_parameters:=path/to/detector_node_params.yaml.

You can also train YOLO to detect custom objects like described here and create the following as detector_node_params.yaml:

/**:
  ros__parameters:
    network:
      config: "./your-yolo-config.cfg"
      weights: "./your-yolo-weights.weights"
      class_names: "./your-cocos.names"
    detection:
      threshold: 0.25
      nms_threshold: 0.45

Finally you can run the detector node with

$ ros2 run openrobotics_darknet_ros detector_node --ros-args --params-file path/to/detector_node_params.yaml

and publish images on ~/images to get the node to detect objects. You can also manually remap an external topic to the ~/images topic with:

$ ros2 run openrobotics_darknet_ros detector_node --ros-args --params-file path/to/detector_node_params.yaml -r '~/images:=/your/camera/topic'