Ros2 Perception

ROS 2 Perception & Computer Vision Instructions (Ubuntu 24.04 LTS & ROS 2 Jazzy)

1. Documentation Entry Points

Any Jazzy package's API docs live at https://docs.ros.org/en/jazzy/p/<package>/ — build the URL from the package name rather than looking one up.

Packages in this domain: image_transport (transport plugins, compressed), cv_bridge (OpenCV conversion), vision_msgs (2D/3D detections), depth_image_proc (depth→cloud, registration), pointcloud_to_laserscan, laser_geometry (scan projection), pcl_ros (PCL bridge).

Verify message field names against the installation itself: ros2 interface show sensor_msgs/msg/Image.

2. Key Concepts & Patterns

cv_bridge OpenCV Conversion (C++)

#include <rclcpp/rclcpp.hpp>
#include <sensor_msgs/msg/image.hpp>
#include <sensor_msgs/image_encodings.hpp>
#include <cv_bridge/cv_bridge.hpp>
#include <opencv2/imgproc/imgproc.hpp>

void process_image(const sensor_msgs::msg::Image::ConstSharedPtr & msg) {
  cv_bridge::CvImagePtr cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::BGR8);
  cv::circle(cv_ptr->image, cv::Point(50, 50), 10, CV_RGB(255, 0, 0), 2);
  sensor_msgs::msg::Image::SharedPtr out_msg = cv_ptr->toImageMsg();
}

3. Symptom -> Root Cause -> Action