1 硬件
摄像头:1个;
USB数据线:1个;
1.1 准备
这里需要使用usb-cam软件包:
$ cd ~/catkin_ws/src
$ git clone https://github.com/bosch-ros-pkg/usb_cam.git
$ cd ~/catkin_ws
$ catkin_make
注意:下面的程序运行前,需要启动usb_cam节点。
roslaunch usb_cam usb_cam-test.launch
运行上面的节点,这时该节点会不断的发布/usb_cam/image_raw话题。
下面的程序将使用这个话题数据。
2 程序
这个程序是对上篇教程的补充。。。对比下,可以更好的分析出一些有意思的东西。
#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include <cv_bridge/cv_bridge.h>
#include <sensor_msgs/image_encodings.h>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
static const std::string OPENCV_WINDOW = "Raw Image window";
static const std::string OPENCV_WINDOW_1 = "Edge Detection";
class Edge_Detector
{
ros::NodeHandle nh_;
image_transport::ImageTransport it_;
image_transport::Subscriber image_sub_;
image_transport::Publisher image_pub_;
public:
Edge_Detector()
: it_(nh_)
{
// Subscribe to input video feed and publish output video feed
image_sub_ = it_.subscribe("/usb_cam/image_raw", 1,
&Edge_Detector::imageCb, this);
image_pub_ = it_.advertise("/edge_detector/raw_image", 1);
cv::namedWindow(OPENCV_WINDOW);
}
~Edge_Detector()
{
cv::destroyWindow(OPENCV_WINDOW);
}
//回调函数
void imageCb(const sensor_msgs::ImageConstPtr& msg)
{
cv_bridge::CvImagePtr cv_ptr;
namespace enc = sensor_msgs::image_encodings;
try
{
cv_ptr = cv_bridge::toCvCopy(msg, sensor_msgs::image_encodings::BGR8);
}
catch (cv_bridge::Exception& e)
{
ROS_ERROR("cv_bridge exception: %s", e.what());
return;
}
// Draw an example circle on the video stream
if (cv_ptr->image.rows > 400 && cv_ptr->image.cols > 600){
detect_edges(cv_ptr->image);
image_pub_.publish(cv_ptr->toImageMsg());
}
}
//OpenCV的边缘检测程序
void detect_edges(cv::Mat img)
{
cv::Mat src, src_gray;
cv::Mat dst, detected_edges;
int edgeThresh = 1;
int lowThreshold = 200;
int highThreshold =300;
int kernel_size = 5;
img.copyTo(src);
cv::cvtColor( img, src_gray, CV_BGR2GRAY );
cv::blur( src_gray, detected_edges, cv::Size(5,5) );
cv::Canny( detected_edges, detected_edges, lowThreshold, highThreshold, kernel_size );
dst = cv::Scalar::all(0);
img.copyTo( dst, detected_edges);
dst.copyTo(img);
cv::imshow(OPENCV_WINDOW, src);
cv::imshow(OPENCV_WINDOW_1, dst);
cv::waitKey(3);
}
};
int main(int argc, char** argv)
{
ros::init(argc, argv, "Edge_Detector");
Edge_Detector ic;
ros::spin();
return 0;
}
2.1 CMakeLists.txt文件
这个很重要,以后再写程序可以直接参考这个文件:
如果有不懂的可以参考ROS学习笔记15(ROS/CMakeLists.txt文件):
https://blog.csdn.net/qq_27806947/article/details/82709620
cmake_minimum_required(VERSION 2.8.3)
project(cv_bridge_tutorial_pkg)
find_package(catkin REQUIRED COMPONENTS
cv_bridge
image_transport
roscpp
sensor_msgs
std_msgs
)
find_package( OpenCV REQUIRED )
catkin_package()
include_directories(
${catkin_INCLUDE_DIRS}
${OpenCV_INCLUDE_DIRS}
)
add_executable(sample_cv_bridge_node src/sample_cv_bridge_node.cpp)
target_link_libraries(sample_cv_bridge_node
${catkin_LIBRARIES}
${OpenCV_LIBRARIES}
)
include_directories(${catkin_INCLUDE_DIRS} ${OpenCV_INCLUDE_DIRS})
2.3 package.xml文件
不懂得也可以参考《ROS学习笔记6(package.xml》
https://blog.csdn.net/qq_27806947/article/details/82084707
<?xml version="1.0"?>
<package>
<name>cv_bridge_tutorial_pkg</name>
<version>0.0.0</version>
<description>The cv_bridge_tutorial_pkg package</description>
<!-- One maintainer tag required, multiple allowed, one person per tag -->
<!-- Example: -->
<!-- <maintainer email="[email protected]">Jane Doe</maintainer> -->
<maintainer email="[email protected]">lentin</maintainer>
<!-- One license tag required, multiple allowed, one license per tag -->
<!-- Commonly used license strings: -->
<!-- BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
<license>TODO</license>
<!-- Url tags are optional, but mutiple are allowed, one per tag -->
<!-- Optional attribute type can be: website, bugtracker, or repository -->
<!-- Example: -->
<!-- <url type="website">http://wiki.ros.org/cv_bridge_tutorial_pkg</url> -->
<!-- Author tags are optional, mutiple are allowed, one per tag -->
<!-- Authors do not have to be maintianers, but could be -->
<!-- Example: -->
<!-- <author email="[email protected]">Jane Doe</author> -->
<!-- The *_depend tags are used to specify dependencies -->
<!-- Dependencies can be catkin packages or system dependencies -->
<!-- Examples: -->
<!-- Use build_depend for packages you need at compile time: -->
<!-- <build_depend>message_generation</build_depend> -->
<!-- Use buildtool_depend for build tool packages: -->
<!-- <buildtool_depend>catkin</buildtool_depend> -->
<!-- Use run_depend for packages you need at runtime: -->
<!-- <run_depend>message_runtime</run_depend> -->
<!-- Use test_depend for packages you need only for testing: -->
<!-- <test_depend>gtest</test_depend> -->
<buildtool_depend>catkin</buildtool_depend>
<build_depend>cv_bridge</build_depend>
<build_depend>image_transport</build_depend>
<build_depend>roscpp</build_depend>
<build_depend>sensor_msgs</build_depend>
<build_depend>std_msgs</build_depend>
<run_depend>cv_bridge</run_depend>
<run_depend>image_transport</run_depend>
<run_depend>roscpp</run_depend>
<run_depend>sensor_msgs</run_depend>
<run_depend>std_msgs</run_depend>
<!-- The export tag contains other, unspecified, tags -->
<export>
<!-- Other tools can request additional information be placed here -->
</export>
</package>
3 运行
首先运行:roscore
然后:roslaunch usb_cam usb_cam-test.launch
最后:rosrun cv_bridge_tutorial_pkg sample_cv_bridge_node
结果如图所示: