ROS 发布和订阅opencv调用的usb摄像头图像
新建目录(有必要的话)
mkdir -p catkin_ws/src
cd catkin_ws
catkin_make新建包 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 src
catkin_create_pkg usb_cam std_msgs roscpp cv_bridge sensor_msgs image_transport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;
} 编辑usb_cam文件夹下的CMakeLists.txt，可以看到前面加的ros的依赖库已经在里面了，这里只需加上opencv的依赖项，然后添加可执行程序并链接相应的库
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})
然后在package.xml中添加
opencv2
opencv2
opencv2 然后就可以进行编译
cd ~/catkin_ws
catkin_make最后进行测试
第一个终端启动
roscore第二个终端发布消息
source ~/catkin_ws/devel/setup.bash
rosrun usb_cam img_publisher第三个终端订阅消息
source ~/catkin_ws/devel/setup.bash
rosrun usb_cam img_viewer完成。
或者使用launch文件同时打开两个节点
在项目目录下新建launch子文件夹，并在其中创立文件openCamera.launch
然后同样的，在启动roscore后，打开新的终端，
source ~/catkin_ws/devel/setup.bash
roslaunch usb_cam openCamera.launch
按ctrl+c可关闭ros服务。如果没反应，可能是终端的快捷键变动过，可以试下ctrl+shift+c或者重置终端设置。