在C++ for ROS2中查找ROS2示例

Question

我一直试图在C++中找到一些示例代码，以了解如何将cv_bridge用于ROS2，但是我得到的唯一示例是来自ROS1的示例。考虑到它使用的是sharedPtr而不是默认的。有人能通过分享如何完成cv_bridge教程中提到的类似任务来启发我吗?该教程正在订阅sensor_msgs::msg::Image，并将其转换为可以由openCV函数操作的内容？任何建议都很感谢，我在这封邮件中附上了我的代码。

#include <memory>

#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
#include "sensor_msgs/msg/image.hpp"
#include <image_transport/image_transport.hpp>

#include <memory>
#include "cv_bridge/cv_bridge.h"
#include <opencv2/opencv.hpp>
// #include <sensor_msgs/msg/image_encodings.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>


#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
using std::placeholders::_1;

class MinimalSubscriber : public rclcpp::Node
{
  public:
    MinimalSubscriber()
    : Node("minimal_subscriber")
    {
      subscription_ = this->create_subscription<sensor_msgs::msg::Image>(
      "topic", 10, std::bind(&MinimalSubscriber::topic_callback, this, _1));
    }

  private:
    void topic_callback(const sensor_msgs::msg::Image::SharedPtr msg) const
    {     
   cv_bridge::CvImagePtr cv_ptr;

      cv_ptr = cv_bridge::toCvCopy(msg,'BGR8' );
     if (cv_ptr->image.rows > 60 && cv_ptr->image.cols > 60)
      cv::circle(cv_ptr->image, cv::Point(50, 50), 10, CV_RGB(255,0,0));
   
    }
    rclcpp::Subscription<sensor_msgs::msg::Image>::SharedPtr subscription_;
    
};

int main(int argc, char * argv[])
{
  rclcpp::init(argc, argv);
  rclcpp::spin(std::make_shared<MinimalSubscriber>());
  rclcpp::shutdown();
  return 0;
}

Answer 1

也许答案有点晚，但这似乎是一个常见的问题。

首先，要构建具有正确的OpenCV和CVBridge依赖项的包，需要将它们包含在CMakeList.txt中。

find_package(cv_bridge REQUIRED)
find_package(OpenCV REQUIRED)

add_subdirectory (../lib lib)

include_directories(
  include
  ${OpenCV_INCLUDE_DIRS}
)

并为您安装的每个目标包括：

ament_target_dependencies(node
  "rclcpp"
  "cv_bridge"
)
  
target_link_libraries(node
  ${OpenCV_LIBS}
)

接下来，在头文件中包括库：

#include <cv_bridge/cv_bridge.h>
#include <opencv2/highgui.hpp>

最后使用cv桥(使用一些示例代码)：

cv_bridge::CvImagePtr cv_ptr;

cv_ptr = cv_bridge::toCvCopy(request->depth_image, request->depth_image.encoding);

cv::patchNaNs(cv_ptr->image, 0.0);

// Datatype depends on your camera image encoding!
if (cv_ptr->image.at<float>(row, col) >= 0.001)
{
    depth = cv_ptr->image.at<float>(row, col);
    return true;
}