Aruco Markers

(1) Dependencies

• Core OpenCV 3 & Extra modules
  • You can follow the instructions found here

(2) Marker Generation

This is a simple C++ program (not a ROS node).

• To compile, cd aruco_markers/src/ & run the following in the terminal:

  g++ aruco_marker_generation.cpp -o aruco_marker_generation `pkg-config --libs opencv` -std=c++11
  

• To run:

  ./aruco_marker_generation
  

• When the OpenCV image window containing a marker image appears, hit the Enter key to continue to build the next one.

• The images will be saved inside the aruco_markers/default_markers directory.

(3) Find Markers

• Follow the instructions here to retrieve the camera calibration .yaml file.

  • Note: You need to get the camera calibration parameters to get an accurate marker location estimate.

• Put the camera_calibration.yaml file inside the aruco_markers/launch/launch_params/ directory.

• Edit the aruco_markers/launch/find_markers.launch file

  • Edit the default parameters to your needs:

    <!-- Set to true if using image from video device
         Set to false if using image from ROS image topic -->
    <arg name="use_video_device" default="true" />
    <!-- If subscribing to ROS image topic, set above arg use_video_device to false -->
    <arg name="image_topic" default="/camera/color/image_raw" />
    
    <!-- video device number from /dev/videoX (e.g. /dev/video0) -->
    <arg name="video_device_num" default="0" />
    <!-- loop rate ~ frames per second -->
    <arg name="loop_rate" default="60" />
    <!-- size of markers in meters -->
    <arg name="marker_size" default="0.031" />
    

  • Update line 11 to the correct filename (i.e. <rosparam command="load" file="$(find aruco_markers)/launch/launch_params/usb_cam_calibration.yaml" />)

• Compile with catkin_make.

• Run with roslaunch aruco_markers find_markers.launch

  • You will see the detected markers under the /markers topic.

  • The raw image will be under the /camera/image_raw topic and the drawn marker image under the /camera/image_marker topic.