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OpenCV Migration

OpenCV Gazebo ROS 1 to ROS 2 Migration

Feb 28, 2026 · 4 min read
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ROS 1 to ROS 2 Migration: OpenCV with Gazebo

This is a documentation of the successful migration of the pkg_cv_ros_tutorial_by_dhanuzch repository from ROS 1 to ROS 2 (Foxy and newer), following the official ROS 2 Migration Guide.

This repository was originally a ROS 1 package used in the “Using OpenCV with Gazebo in ROS” tutorial series by @dhanuzch. It has now been ported and is available at:
GitHub Repository: pkg_cv_ros_tutorial_by_dhanuzch

The migration includes updating package manifests, the build system (ament_cmake), Python source code for nodes, and transitioning ROS 1 XML launch files to ROS 2 Python launch files.

Proposed Changes

Phase 1: Package Manifest and Build System

Ensure the package’s foundation is fully ROS 2 compliant. Update dependencies and build configurations to use ament_cmake.

package.xml

  • Changed <package format="2"> to at least format 3 for ROS 2 compatibility.
  • Replaced <buildtool_depend>catkin</buildtool_depend> with <buildtool_depend>ament_cmake</buildtool_depend>.
  • Replaced occurrences of rospy with rclpy.
  • Added sensor_msgs and cv_bridge as <exec_depend>.
  • Added <export><build_type>ament_cmake</build_type></export>.

CMakeLists.txt

  • Updated cmake_minimum_required to VERSION 3.8.
  • Replaced find_package(catkin ...) with find_package(ament_cmake REQUIRED).
  • Used install(PROGRAMS ...) to install the Python scripts into lib/${PROJECT_NAME} so they can be executed natively.
  • Replaced catkin_package() with ament_package().

Phase 2: Python Node Migration

Migrate the ROS 1 specific Python code (rospy) to the ROS 2 API (rclpy).

scripts/camera_read.py & scripts/decode_qr.py

  • Changed import rospy to import rclpy and included from rclpy.node import Node.
  • Ensured script node classes inherit natively from Node and updated constructors via super().__init__().
  • Replaced rospy.Subscriber with self.create_subscription().
  • Built modern logging (self.get_logger().info()).
  • Updated main() execution blocks to leverage rclpy.spin().

Phase 3: Launch Files and Testing

Recreate the environment execution flow using ROS 2 Python launch files and conduct final system integration and testing.

launch/1_world_and_script.launch.py

  • Created a modern ROS 2 Python launch script importing logic to extend GAZEBO_MODEL_PATH.
  • Added Node execution actions sequentially alongside simulation boots.

launch/2_world_and_script.launch.py

  • Converted the legacy target to spawn the QR-decoding process seamlessly via concurrent ExecuteProcess dependencies!

Verification Plan

Automated/Compilation Tests

  1. Run colcon build --symlink-install from the workspace root.
  2. Ensure the package compiles cleanly without CMake or ament errors.
  3. Verify that source install/setup.bash makes the package correctly visible to ros2 pkg list.

System Integration & Manual Verification

To manually test:

  • Initiate the simulation using ros2 launch pkg_cv_ros_tutorial_by_dhanuzch 1_world_and_script.launch.py.
  • Confirm that the cv2.imshow window appears and natively resolves drone camera outputs.
  • Test 2_world_and_script.launch.py to confirm QR decoding highlights!