ROS工程实践2—usb_camera工程

一、创建包

新建一个包名为 usb_cam，其中附加的依赖有std_msgs（消息传递），roscpp（c++），cv_bridge（ros和opencv图像转换），sensor_msgs（传感器消息），image_transport（图像编码传输）

 cd catkin_ws/src
     
 catkin_create_pkg usb_cam std_msgs roscpp cv_bridge sensor_msgs image_transport

二、创建节点

在usb_cam/src文件夹中添加两个cpp，一个发布图像消息img_publisher.cpp，一个接收并查看图像消息img_viewer.cpp

img_publisher.cpp

  

#include 
    #include 
    #include 
    #include 
    #include 
    #include 
     
    int main(int argc, char** argv)
    {
      ros::init(argc, argv, "img_publisher");
      ros::NodeHandle nh;
      image_transport::ImageTransport it(nh);
      image_transport::Publisher pub = it.advertise("camera/image", 1);
     
      cv::VideoCapture cap;
      cv::Mat frame;
      int deviceID=0;
      if(argc>1)
        deviceID=argv[1][0]-'0';
      int apiID=cv::CAP_ANY;
      cap.open(deviceID+apiID);
      if(!cap.isOpened()){
        std::cerr<<"ERROR! Unable to open camera"<

img_viewer.cpp

   

#include 
    #include 
    #include 
    #include 
     
    void imageCallback(const sensor_msgs::ImageConstPtr& msg)
    {
      try
      {
        cv::imshow("view", cv_bridge::toCvShare(msg, "bgr8")->image);
      }
      catch (cv_bridge::Exception& e)
      {
        ROS_ERROR("Could not convert from '%s' to 'bgr8'.", msg->encoding.c_str());
      }
    }
     
    int main(int argc, char **argv)
    {
      ros::init(argc, argv, "img_viewer");
      ros::NodeHandle nh;
      cv::namedWindow("view");
      cv::startWindowThread();
      image_transport::ImageTransport it(nh);
      image_transport::Subscriber sub = it.subscribe("camera/image", 1, imageCallback);
      ros::spin();
      cv::destroyWindow("view");
      return 0;
    }

三、修改CMakeLists.txt及package.xml

打开CMakeLists.txt可以看到ros的依赖库已经添加了，这里只需要再加上OpenCV的依赖并链接相应库就可以了。

find_package(catkin REQUIRED COMPONENTS
      cv_bridge
      image_transport
      roscpp
      sensor_msgs
      std_msgs
    )
    find_package(OpenCV REQUIRED)
     
    include_directories(
      ${catkin_INCLUDE_DIRS}
      ${OpenCV_INCLUDE_DIRS}
    )
     
    add_executable(img_publisher src/img_publisher.cpp)
    add_executable(img_viewer src/img_viewer.cpp)
     
    target_link_libraries(img_publisher ${catkin_LIBRARIES} ${OpenCV_LIBS})
    target_link_libraries(img_viewer ${catkin_LIBRARIES} ${OpenCV_LIBS})

接着修改package.xml文件，在里面添加

opencv2
    opencv2
    opencv2

四、编译运行

  cd ~/catkin_ws
   catkin_make

先启动ros

roscore

开两个终端分别启动节点   

 source ~/catkin_ws/devel/setup.bash
 rosrun usb_cam img_publisher

 source ~/catkin_ws/devel/setup.bash
 rosrun usb_cam img_viewer

完成！