Is that possible to synchronize an average 5 fps topic with 100 fps topic? Did I init subscriber in corret place?

edit

Hi there,

I have a YOLO detector topic which produces Boundingboxes with average rate 2-5.

My another topic has average 100 rate.

Is that possible to synchronize both topics? And how to set the queue size or any other arguments for sync CallBack?

Right now thw ROS_INFO_STREAM inside synCB does not print onto screen, i.e. synCB is not reacted.

In pupildarknet.h I declare a class and initialize message_filters.Subscriber in the class constructor. Did I initialize in wrong place?

#ifndef PUPILDARKNET_H
#define PUPILDARKNET_H

#include <boost/bind.hpp>
#include <ros/ros.h>
#include <std_msgs/Int8.h>
#include <darknet_ros_msgs/BoundingBox.h>
#include <darknet_ros_msgs/BoundingBoxes.h>
#include <sensor_msgs/Image.h>
#include <pupil_ros_plugin/gaze_positions.h>

#include <message_filters/subscriber.h>
#include <message_filters/time_synchronizer.h>
#include <message_filters/sync_policies/approximate_time.h>

#include <image_transport/image_transport.h>
#include <sensor_msgs/image_encodings.h>
#include <sensor_msgs/Image.h>

#include <cv_bridge/cv_bridge.h>

#include <opencv2/core.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/imgproc.hpp>

#include <iostream>
using namespace cv;
using namespace std;

class PupilDarknet {
private:
  ros::NodeHandle nh_;
  ros::Subscriber sub_numDetObj;

  pupil_ros_plugin::gaze_positions in_gaze;
  cv_bridge::CvImagePtr in_cv_ptr;
  darknet_ros_msgs::BoundingBoxes in_bbes;
  std_msgs::Int8 numDetObj;

  bool verbose;
  /// TODO: CHECK DIFF BETWEEN DECLARATION AS PRIVATE MEMBERS AND IN CONSTRUCTOR.
  //  message_filters::Subscriber<pupil_ros_plugin::gaze_positions> sub_gazePose;
  //  message_filters::Subscriber<sensor_msgs::Image> sub_image;
  //  message_filters::Subscriber<darknet_ros_msgs::BoundingBoxes> sub_DarkentBBes;

public:
  PupilDarknet(ros::NodeHandle nh) : nh_(nh)
  {
      numDetObj.data = 0;

      message_filters::Subscriber<sensor_msgs::Image> sub_image(nh_,"/camera/rgb/image_raw",30);
      message_filters::Subscriber<darknet_ros_msgs::BoundingBoxes> sub_DarkentBBes(nh_,"/darknet_ros/bounding_boxes",30);
      message_filters::Subscriber<pupil_ros_plugin::gaze_positions> sub_gazePose(nh_,"/pupil_capture/gaze",30);

      typedef message_filters::sync_policies::ApproximateTime<
          sensor_msgs::Image,
          darknet_ros_msgs::BoundingBoxes,
          pupil_ros_plugin::gaze_positions> syncPolicy;

      message_filters::Synchronizer<syncPolicy> sync(
            syncPolicy(1),
            sub_image,
            sub_DarkentBBes,
            sub_gazePose);

      sync.registerCallback(boost::bind(&PupilDarknet::synCB,this, _1,_2,_3));

      sub_numDetObj = nh_.subscribe("/darknet_ros/found_object", 1, &PupilDarknet::getNumDetObj, this);

  }
  ~PupilDarknet(){}

  void getNumDetObj(std_msgs::Int8 msg);
  void synCB(const sensor_msgs::ImageConstPtr& img,
             const darknet_ros_msgs::BoundingBoxesConstPtr& BBes,
             const pupil_ros_plugin::gaze_positionsConstPtr& gaze);

};

#endif // PUPILDARKNET_H

My cpp file:

void PupilDarknet::synCB(const sensor_msgs::ImageConstPtr& img, const darknet_ros_msgs::BoundingBoxesConstPtr& BBes, const pupil_ros_plugin::gaze_positionsConstPtr& gaze)
{
  ROS_INFO_STREAM("Hello This is pupil_darknet synCB...");
}