大家好，又见面了，我是你们的朋友全栈君。
目录
三、修改CMakeLists.txt及package.xml
前言
ros教程：OpenCV调用usb摄像头
创建功能包教程在ROS教程（三）：创建程序包及节点（图文）已讲解，本文便不再细讲。
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 <ros/ros.h>
#include <image_transport/image_transport.h>
#include <opencv2/highgui.hpp>
#include <opencv2/calib3d.hpp>
#include <cv_bridge/cv_bridge.h>
#include <iostream>
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"<<std::endl;
return -1;
}
ros::Rate loop_rate(30);
while (nh.ok()) {
cap.read(frame);
if(!frame.empty()){
sensor_msgs::ImagePtr msg = cv_bridge::CvImage(std_msgs::Header(), "bgr8", frame).toImageMsg();
pub.publish(msg);
}
ros::spinOnce();
loop_rate.sleep();
}
return 0;
}img_viewer.cpp
#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <opencv2/highgui/highgui.hpp>
#include <cv_bridge/cv_bridge.h>
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
<build_depend>opencv2</build_depend>
<build_export_depend>opencv2</build_export_depend>
<exec_depend>opencv2</exec_depend>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！
总结（最重要的）
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