ROS 接收两个图像话题 并进行时间同步

利用message_filters进行同步操作,然后在一个回调函数中显示和处理两种图像.

对齐传感信息时间戳有两种方式，一种是时间戳完全对齐 ExactTime Policy ，另一种是时间戳相近 ApproximateTime Policy ，前者更为严格.

#include <ros/ros.h>
#include <image_transport/image_transport.h>
#include<opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include "sensor_msgs/image_encodings.h"     
#include <cv_bridge/cv_bridge.h>
#include <message_filters/subscriber.h>
#include <message_filters/synchronizer.h>
#include <message_filters/sync_policies/exact_time.h>
#include <message_filters/sync_policies/approximate_time.h>//相近对齐
#include <message_filters/time_synchronizer.h>
#include"std_msgs/UInt16MultiArray.h"  
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
 
using namespace cv;
using namespace std;
using namespace sensor_msgs;
using namespace message_filters;

class mySynchronizer{
    
    
public:
     mySynchronizer();
    ~mySynchronizer(){
    
    };

    void callback(const sensor_msgs::ImageConstPtr &RGB_image, const sensor_msgs::ImageConstPtr &depth_image);    
};
void mySynchronizer::callback(const sensor_msgs::ImageConstPtr &RGB_image,const  sensor_msgs::ImageConstPtr &depth_image){
    
        
    try
    {
    
           
      cv_bridge::CvImagePtr image_ptr = cv_bridge::toCvCopy(RGB_image, sensor_msgs::image_encodings::BGR8);
      cv::Mat RGB_image= image_ptr->image;     
 
       cv_bridge::CvImagePtr image_ptr1 = cv_bridge::toCvCopy(depth_image, sensor_msgs::image_encodings::BGR8);
      cv::Mat depth_image= image_ptr1->image; 

      cv::imshow("rgb_camera",RGB_image);
      cv::imshow("depth_camera",depth_image);
      cv::waitKey(10);
    }
    catch(cv_bridge::Exception &e)
    {
    
    
      ROS_ERROR("cv_bridge Exception %s",e.what());
    }
}

mySynchronizer::mySynchronizer()
{
    
    
    ros::NodeHandle nh; 
    
    message_filters::Subscriber<sensor_msgs::Image> image_sub(nh, "/stereo_camera/RGB", 1);
    message_filters::Subscriber<sensor_msgs::Image> render_sub(nh, "/stereo_camera/render", 1); 


    typedef message_filters::sync_policies::ExactTime<sensor_msgs::Image, sensor_msgs::Image> MySyncPolicy;
    message_filters::Synchronizer<MySyncPolicy> sync(MySyncPolicy(10), image_sub, render_sub);
    sync.registerCallback(boost::bind(&mySynchronizer::callback, this, _1, _2));
    ros::spin();
}


int main(int argc, char** argv)
{
    
    
    ros::init(argc, argv, "msg_synchronizer");   
    mySynchronizer wode;  
    return 0;
}