stereo_processor.h

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#ifndef STEREO_PROCESSOR_H_
#define STEREO_PROCESSOR_H_

#include <ros/ros.h>
#include <sensor_msgs/Image.h>
#include <sensor_msgs/CameraInfo.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>
#include <image_transport/subscriber_filter.h>

namespace viso2_ros
{

class StereoProcessor
{

private:

  // subscriber
  image_transport::SubscriberFilter left_sub_, right_sub_;
  message_filters::Subscriber<sensor_msgs::CameraInfo> left_info_sub_, right_info_sub_;
  typedef message_filters::sync_policies::ExactTime<sensor_msgs::Image, sensor_msgs::Image, sensor_msgs::CameraInfo, sensor_msgs::CameraInfo> ExactPolicy;
  typedef message_filters::sync_policies::ApproximateTime<sensor_msgs::Image, sensor_msgs::Image, sensor_msgs::CameraInfo, sensor_msgs::CameraInfo> ApproximatePolicy;
  typedef message_filters::Synchronizer<ExactPolicy> ExactSync;
  typedef message_filters::Synchronizer<ApproximatePolicy> ApproximateSync;
  boost::shared_ptr<ExactSync> exact_sync_;
  boost::shared_ptr<ApproximateSync> approximate_sync_;
  int queue_size_;

  // for sync checking
  ros::WallTimer check_synced_timer_;
  int left_received_, right_received_, left_info_received_, right_info_received_, all_received_;

  // for sync checking
  static void increment(int* value)
  {
    ++(*value);
  }

  void dataCb(const sensor_msgs::ImageConstPtr& l_image_msg,
              const sensor_msgs::ImageConstPtr& r_image_msg,
              const sensor_msgs::CameraInfoConstPtr& l_info_msg,
              const sensor_msgs::CameraInfoConstPtr& r_info_msg)
  {
 
    // For sync error checking
    ++all_received_; 

    // call implementation
    imageCallback(l_image_msg, r_image_msg, l_info_msg, r_info_msg);
  }

  void checkInputsSynchronized()
  {
    int threshold = 3 * all_received_;
    if (left_received_ >= threshold || right_received_ >= threshold || 
        left_info_received_ >= threshold || right_info_received_ >= threshold) {
      ROS_WARN("[stereo_processor] Low number of synchronized left/right/left_info/right_info tuples received.\n"
               "Left images received:       %d (topic '%s')\n"
               "Right images received:      %d (topic '%s')\n"
               "Left camera info received:  %d (topic '%s')\n"
               "Right camera info received: %d (topic '%s')\n"
               "Synchronized tuples: %d\n"
               "Possible issues:\n"
               "\t* stereo_image_proc is not running.\n"
               "\t  Does `rosnode info %s` show any connections?\n"
               "\t* The cameras are not synchronized.\n"
               "\t  Try restarting the node with parameter _approximate_sync:=True\n"
               "\t* The network is too slow. One or more images are dropped from each tuple.\n"
               "\t  Try restarting the node, increasing parameter 'queue_size' (currently %d)",
               left_received_, left_sub_.getTopic().c_str(),
               right_received_, right_sub_.getTopic().c_str(),
               left_info_received_, left_info_sub_.getTopic().c_str(),
               right_info_received_, right_info_sub_.getTopic().c_str(),
               all_received_, ros::this_node::getName().c_str(), queue_size_);
    }
  }


protected:

  StereoProcessor(const std::string& transport) :
    left_received_(0), right_received_(0), left_info_received_(0), right_info_received_(0), all_received_(0)
  {
    // Read local parameters
    ros::NodeHandle local_nh("~");

    // Resolve topic names
    ros::NodeHandle nh;
    std::string stereo_ns = nh.resolveName("stereo");
    std::string left_topic = ros::names::clean(stereo_ns + "/left/" + nh.resolveName("image"));
    std::string right_topic = ros::names::clean(stereo_ns + "/right/" + nh.resolveName("image"));

    std::string left_info_topic = stereo_ns + "/left/camera_info";
    std::string right_info_topic = stereo_ns + "/right/camera_info";

    // Subscribe to four input topics.
    ROS_INFO("Subscribing to:\n\t* %s\n\t* %s\n\t* %s\n\t* %s", 
        left_topic.c_str(), right_topic.c_str(),
        left_info_topic.c_str(), right_info_topic.c_str());

    image_transport::ImageTransport it(nh);
    left_sub_.subscribe(it, left_topic, 1, transport);
    right_sub_.subscribe(it, right_topic, 1, transport);
    left_info_sub_.subscribe(nh, left_info_topic, 1);
    right_info_sub_.subscribe(nh, right_info_topic, 1);

    // Complain every 15s if the topics appear unsynchronized
    left_sub_.registerCallback(boost::bind(StereoProcessor::increment, &left_received_));
    right_sub_.registerCallback(boost::bind(StereoProcessor::increment, &right_received_));
    left_info_sub_.registerCallback(boost::bind(StereoProcessor::increment, &left_info_received_));
    right_info_sub_.registerCallback(boost::bind(StereoProcessor::increment, &right_info_received_));
    check_synced_timer_ = nh.createWallTimer(ros::WallDuration(15.0),
                                             boost::bind(&StereoProcessor::checkInputsSynchronized, this));

    // Synchronize input topics. Optionally do approximate synchronization.
    local_nh.param("queue_size", queue_size_, 5);
    bool approx;
    local_nh.param("approximate_sync", approx, false);
    if (approx)
    {
      approximate_sync_.reset(new ApproximateSync(ApproximatePolicy(queue_size_),
                                                  left_sub_, right_sub_, left_info_sub_, right_info_sub_) );
      approximate_sync_->registerCallback(boost::bind(&StereoProcessor::dataCb, this, _1, _2, _3, _4));
    }
    else
    {
      exact_sync_.reset(new ExactSync(ExactPolicy(queue_size_),
                                      left_sub_, right_sub_, left_info_sub_, right_info_sub_) );
      exact_sync_->registerCallback(boost::bind(&StereoProcessor::dataCb, this, _1, _2, _3, _4));
    }
  }

  virtual void imageCallback(const sensor_msgs::ImageConstPtr& l_image_msg,
                             const sensor_msgs::ImageConstPtr& r_image_msg,
                             const sensor_msgs::CameraInfoConstPtr& l_info_msg,
                             const sensor_msgs::CameraInfoConstPtr& r_info_msg) = 0;

};

} // end of namespace

#endif