slam_karto_g2o.cpp

/*
 * slam_karto
 * Copyright (c) 2008, Willow Garage, Inc.
 *
 * THE WORK (AS DEFINED BELOW) IS PROVIDED UNDER THE TERMS OF THIS CREATIVE
 * COMMONS PUBLIC LICENSE ("CCPL" OR "LICENSE"). THE WORK IS PROTECTED BY
 * COPYRIGHT AND/OR OTHER APPLICABLE LAW. ANY USE OF THE WORK OTHER THAN AS
 * AUTHORIZED UNDER THIS LICENSE OR COPYRIGHT LAW IS PROHIBITED.
 *
 * BY EXERCISING ANY RIGHTS TO THE WORK PROVIDED HERE, YOU ACCEPT AND AGREE TO
 * BE BOUND BY THE TERMS OF THIS LICENSE. THE LICENSOR GRANTS YOU THE RIGHTS
 * CONTAINED HERE IN CONSIDERATION OF YOUR ACCEPTANCE OF SUCH TERMS AND
 * CONDITIONS.
 *
 */

/* Author: Brian Gerkey */

/*********************************************************************
*
*  Copyright (c) 2017, Saurav Agarwal 
*  All rights reserved.
*
*********************************************************************/

#include "ros/ros.h"
#include "ros/console.h"
#include "message_filters/subscriber.h"
#include "tf/transform_broadcaster.h"
#include "tf/transform_listener.h"
#include "tf/message_filter.h"
#include "visualization_msgs/MarkerArray.h"

#include "nav_msgs/MapMetaData.h"
#include "sensor_msgs/LaserScan.h"
#include "nav_msgs/GetMap.h"

#include "open_karto/Mapper.h"

#include "G2OSolver.h"

#include <boost/thread.hpp>

#include <string>
#include <map>
#include <vector>

// compute linear index for given map coords
#define MAP_IDX(sx, i, j) ((sx) * (j) + (i))

class SlamKarto
{
  public:
    SlamKarto();
    ~SlamKarto();

    void laserCallback(const sensor_msgs::LaserScan::ConstPtr& scan);
    bool mapCallback(nav_msgs::GetMap::Request  &req,
                     nav_msgs::GetMap::Response &res);

  private:
    bool getOdomPose(karto::Pose2& karto_pose, const ros::Time& t);
    karto::LaserRangeFinder* getLaser(const sensor_msgs::LaserScan::ConstPtr& scan);
    bool addScan(karto::LaserRangeFinder* laser,
                 const sensor_msgs::LaserScan::ConstPtr& scan,
                 karto::Pose2& karto_pose);
    bool updateMap();
    void publishTransform();
    void publishLoop(double transform_publish_period);
    void publishGraphVisualization();

    // ROS handles
    ros::NodeHandle node_;
    tf::TransformListener tf_;
    tf::TransformBroadcaster* tfB_;
    message_filters::Subscriber<sensor_msgs::LaserScan>* scan_filter_sub_;
    tf::MessageFilter<sensor_msgs::LaserScan>* scan_filter_;
    ros::Publisher sst_;
    ros::Publisher marker_publisher_;
    ros::Publisher sstm_;
    ros::ServiceServer ss_;

    // The map that will be published / send to service callers
    nav_msgs::GetMap::Response map_;

    // Storage for ROS parameters
    std::string odom_frame_;
    std::string map_frame_;
    std::string base_frame_;
    int throttle_scans_;
    ros::Duration map_update_interval_;
    double resolution_;
    boost::mutex map_mutex_;
    boost::mutex map_to_odom_mutex_;

    // Karto bookkeeping
    karto::Mapper* mapper_;
    karto::Dataset* dataset_;
    G2OSolver* solver_;
    std::map<std::string, karto::LaserRangeFinder*> lasers_;
    std::map<std::string, bool> lasers_inverted_;

    // Internal state
    bool got_map_;
    int laser_count_;
    boost::thread* transform_thread_;
    tf::Transform map_to_odom_;
    unsigned marker_count_;
    bool inverted_laser_;
    bool use_robust_kernel_;
};

SlamKarto::SlamKarto() :
        got_map_(false),
        laser_count_(0),
        transform_thread_(NULL),
        marker_count_(0)
{
  map_to_odom_.setIdentity();
  
  // Retrieve parameters
  ros::NodeHandle private_nh_("~");

  if(!private_nh_.getParam("use_robust_kernel", use_robust_kernel_))
  {
    use_robust_kernel_ = false;
  }

  if(!private_nh_.getParam("odom_frame", odom_frame_))
    odom_frame_ = "odom";
  if(!private_nh_.getParam("map_frame", map_frame_))
    map_frame_ = "map";
  if(!private_nh_.getParam("base_frame", base_frame_))
    base_frame_ = "base_link";
  if(!private_nh_.getParam("throttle_scans", throttle_scans_))
    throttle_scans_ = 1;
  double tmp;
  if(!private_nh_.getParam("map_update_interval", tmp))
    tmp = 5.0;
  map_update_interval_.fromSec(tmp);
  if(!private_nh_.getParam("resolution", resolution_))
  {
    // Compatibility with slam_gmapping, which uses "delta" to mean
    // resolution
    if(!private_nh_.getParam("delta", resolution_))
      resolution_ = 0.05;
  }
  double transform_publish_period;
  private_nh_.param("transform_publish_period", transform_publish_period, 0.05);

  // Set up advertisements and subscriptions
  tfB_ = new tf::TransformBroadcaster();
  sst_ = node_.advertise<nav_msgs::OccupancyGrid>("map", 1, true);
  sstm_ = node_.advertise<nav_msgs::MapMetaData>("map_metadata", 1, true);
  ss_ = node_.advertiseService("dynamic_map", &SlamKarto::mapCallback, this);
  scan_filter_sub_ = new message_filters::Subscriber<sensor_msgs::LaserScan>(node_, "scan", 5);
  scan_filter_ = new tf::MessageFilter<sensor_msgs::LaserScan>(*scan_filter_sub_, tf_, odom_frame_, 5);
  scan_filter_->registerCallback(boost::bind(&SlamKarto::laserCallback, this, _1));
  marker_publisher_ = node_.advertise<visualization_msgs::MarkerArray>("visualization_marker_array",1);

  // Create a thread to periodically publish the latest map->odom
  // transform; it needs to go out regularly, uninterrupted by potentially
  // long periods of computation in our main loop.
  transform_thread_ = new boost::thread(boost::bind(&SlamKarto::publishLoop, this, transform_publish_period));

  // Initialize Karto structures
  mapper_ = new karto::Mapper();
  dataset_ = new karto::Dataset();

  // Setting General Parameters from the Parameter Server
  bool use_scan_matching = true;
  if(private_nh_.getParam("use_scan_matching", use_scan_matching))
    mapper_->setParamUseScanMatching(use_scan_matching);
  
  bool use_scan_barycenter;
  if(private_nh_.getParam("use_scan_barycenter", use_scan_barycenter))
    mapper_->setParamUseScanBarycenter(use_scan_barycenter);

  double minimum_travel_distance;
  if(private_nh_.getParam("minimum_travel_distance", minimum_travel_distance))
    mapper_->setParamMinimumTravelDistance(minimum_travel_distance);

  double minimum_travel_heading;
  if(private_nh_.getParam("minimum_travel_heading", minimum_travel_heading))
    mapper_->setParamMinimumTravelHeading(minimum_travel_heading);

  int scan_buffer_size;
  if(private_nh_.getParam("scan_buffer_size", scan_buffer_size))
    mapper_->setParamScanBufferSize(scan_buffer_size);

  double scan_buffer_maximum_scan_distance;
  if(private_nh_.getParam("scan_buffer_maximum_scan_distance", scan_buffer_maximum_scan_distance))
    mapper_->setParamScanBufferMaximumScanDistance(scan_buffer_maximum_scan_distance);

  double link_match_minimum_response_fine;
  if(private_nh_.getParam("link_match_minimum_response_fine", link_match_minimum_response_fine))
    mapper_->setParamLinkMatchMinimumResponseFine(link_match_minimum_response_fine);

  double link_scan_maximum_distance;
  if(private_nh_.getParam("link_scan_maximum_distance", link_scan_maximum_distance))
    mapper_->setParamLinkScanMaximumDistance(link_scan_maximum_distance);

  double loop_search_maximum_distance;
  if(private_nh_.getParam("loop_search_maximum_distance", loop_search_maximum_distance))
    mapper_->setParamLoopSearchMaximumDistance(loop_search_maximum_distance);

  bool do_loop_closing;
  if(private_nh_.getParam("do_loop_closing", do_loop_closing))
    mapper_->setParamDoLoopClosing(do_loop_closing);

  int loop_match_minimum_chain_size;
  if(private_nh_.getParam("loop_match_minimum_chain_size", loop_match_minimum_chain_size))
    mapper_->setParamLoopMatchMinimumChainSize(loop_match_minimum_chain_size);

  double loop_match_maximum_variance_coarse;
  if(private_nh_.getParam("loop_match_maximum_variance_coarse", loop_match_maximum_variance_coarse))
    mapper_->setParamLoopMatchMaximumVarianceCoarse(loop_match_maximum_variance_coarse);

  double loop_match_minimum_response_coarse;
  if(private_nh_.getParam("loop_match_minimum_response_coarse", loop_match_minimum_response_coarse))
    mapper_->setParamLoopMatchMinimumResponseCoarse(loop_match_minimum_response_coarse);

  double loop_match_minimum_response_fine;
  if(private_nh_.getParam("loop_match_minimum_response_fine", loop_match_minimum_response_fine))
    mapper_->setParamLoopMatchMinimumResponseFine(loop_match_minimum_response_fine);

  // Setting Correlation Parameters from the Parameter Server

  double correlation_search_space_dimension;
  if(private_nh_.getParam("correlation_search_space_dimension", correlation_search_space_dimension))
    mapper_->setParamCorrelationSearchSpaceDimension(correlation_search_space_dimension);

  double correlation_search_space_resolution;
  if(private_nh_.getParam("correlation_search_space_resolution", correlation_search_space_resolution))
    mapper_->setParamCorrelationSearchSpaceResolution(correlation_search_space_resolution);

  double correlation_search_space_smear_deviation;
  if(private_nh_.getParam("correlation_search_space_smear_deviation", correlation_search_space_smear_deviation))
    mapper_->setParamCorrelationSearchSpaceSmearDeviation(correlation_search_space_smear_deviation);

  // Setting Correlation Parameters, Loop Closure Parameters from the Parameter Server

  double loop_search_space_dimension;
  if(private_nh_.getParam("loop_search_space_dimension", loop_search_space_dimension))
    mapper_->setParamLoopSearchSpaceDimension(loop_search_space_dimension);

  double loop_search_space_resolution;
  if(private_nh_.getParam("loop_search_space_resolution", loop_search_space_resolution))
    mapper_->setParamLoopSearchSpaceResolution(loop_search_space_resolution);

  double loop_search_space_smear_deviation;
  if(private_nh_.getParam("loop_search_space_smear_deviation", loop_search_space_smear_deviation))
    mapper_->setParamLoopSearchSpaceSmearDeviation(loop_search_space_smear_deviation);

  // Setting Scan Matcher Parameters from the Parameter Server

  double distance_variance_penalty;
  if(private_nh_.getParam("distance_variance_penalty", distance_variance_penalty))
    mapper_->setParamDistanceVariancePenalty(distance_variance_penalty);

  double angle_variance_penalty;
  if(private_nh_.getParam("angle_variance_penalty", angle_variance_penalty))
    mapper_->setParamAngleVariancePenalty(angle_variance_penalty);

  double fine_search_angle_offset;
  if(private_nh_.getParam("fine_search_angle_offset", fine_search_angle_offset))
    mapper_->setParamFineSearchAngleOffset(fine_search_angle_offset);

  double coarse_search_angle_offset;
  if(private_nh_.getParam("coarse_search_angle_offset", coarse_search_angle_offset))
    mapper_->setParamCoarseSearchAngleOffset(coarse_search_angle_offset);

  double coarse_angle_resolution;
  if(private_nh_.getParam("coarse_angle_resolution", coarse_angle_resolution))
    mapper_->setParamCoarseAngleResolution(coarse_angle_resolution);

  double minimum_angle_penalty;
  if(private_nh_.getParam("minimum_angle_penalty", minimum_angle_penalty))
    mapper_->setParamMinimumAnglePenalty(minimum_angle_penalty);

  double minimum_distance_penalty;
  if(private_nh_.getParam("minimum_distance_penalty", minimum_distance_penalty))
    mapper_->setParamMinimumDistancePenalty(minimum_distance_penalty);

  bool use_response_expansion;
  if(private_nh_.getParam("use_response_expansion", use_response_expansion))
    mapper_->setParamUseResponseExpansion(use_response_expansion);

  // Set solver to be used in loop closure
  solver_ = new G2OSolver();

  solver_->useRobustKernel(use_robust_kernel_);
  
  mapper_->SetScanSolver(solver_);
}

SlamKarto::~SlamKarto()
{
  if(transform_thread_)
  {
    transform_thread_->join();
    delete transform_thread_;
  }
  if (scan_filter_)
    delete scan_filter_;
  if (scan_filter_sub_)
    delete scan_filter_sub_;
  if (solver_)
    delete solver_;
  if (mapper_)
    delete mapper_;
  if (dataset_)
    delete dataset_;
  // TODO: delete the pointers in the lasers_ map; not sure whether or not
  // I'm supposed to do that.
}

void
SlamKarto::publishLoop(double transform_publish_period)
{
  if(transform_publish_period == 0)
    return;

  ros::Rate r(1.0 / transform_publish_period);
  while(ros::ok())
  {
    publishTransform();
    r.sleep();
  }
}

void
SlamKarto::publishTransform()
{
  boost::mutex::scoped_lock lock(map_to_odom_mutex_);
  ros::Time tf_expiration = ros::Time::now() + ros::Duration(0.05);
  tfB_->sendTransform(tf::StampedTransform (map_to_odom_, ros::Time::now(), map_frame_, odom_frame_));
}

karto::LaserRangeFinder*
SlamKarto::getLaser(const sensor_msgs::LaserScan::ConstPtr& scan)
{
  // Check whether we know about this laser yet
  if(lasers_.find(scan->header.frame_id) == lasers_.end())
  {
    // New laser; need to create a Karto device for it.

    // Get the laser's pose, relative to base.
    tf::Stamped<tf::Pose> ident;
    tf::Stamped<tf::Transform> laser_pose;
    ident.setIdentity();
    ident.frame_id_ = scan->header.frame_id;
    ident.stamp_ = scan->header.stamp;
    try
    {
      tf_.transformPose(base_frame_, ident, laser_pose);
    }
    catch(tf::TransformException e)
    {
      ROS_WARN("Failed to compute laser pose, aborting initialization (%s)",
	       e.what());
      return NULL;
    }

    double yaw = tf::getYaw(laser_pose.getRotation());

    ROS_INFO("laser %s's pose wrt base: %.3f %.3f %.3f",
	     scan->header.frame_id.c_str(),
	     laser_pose.getOrigin().x(),
	     laser_pose.getOrigin().y(),
	     yaw);
    // To account for lasers that are mounted upside-down,
    // we create a point 1m above the laser and transform it into the laser frame
    // if the point's z-value is <=0, it is upside-down

    tf::Vector3 v;
    v.setValue(0, 0, 1 + laser_pose.getOrigin().z());
    tf::Stamped<tf::Vector3> up(v, scan->header.stamp, base_frame_);

    try
    {
      tf_.transformPoint(scan->header.frame_id, up, up);
      ROS_DEBUG("Z-Axis in sensor frame: %.3f", up.z());
    }
    catch (tf::TransformException& e)
    {
      ROS_WARN("Unable to determine orientation of laser: %s", e.what());
      return NULL;
    }

    bool inverse = lasers_inverted_[scan->header.frame_id] = up.z() <= 0;
    if (inverse)
      ROS_INFO("laser is mounted upside-down");


    // Create a laser range finder device and copy in data from the first
    // scan
    std::string name = scan->header.frame_id;
    karto::LaserRangeFinder* laser = 
      karto::LaserRangeFinder::CreateLaserRangeFinder(karto::LaserRangeFinder_Custom, karto::Name(name));
    laser->SetOffsetPose(karto::Pose2(laser_pose.getOrigin().x(),
				      laser_pose.getOrigin().y(),
				      yaw));
    laser->SetMinimumRange(scan->range_min);
    laser->SetMaximumRange(scan->range_max);
    laser->SetMinimumAngle(scan->angle_min);
    laser->SetMaximumAngle(scan->angle_max);
    laser->SetAngularResolution(scan->angle_increment);
    // TODO: expose this, and many other parameters
    //laser_->SetRangeThreshold(12.0);

    // Store this laser device for later
    lasers_[scan->header.frame_id] = laser;

    // Add it to the dataset, which seems to be necessary
    dataset_->Add(laser);
  }

  return lasers_[scan->header.frame_id];
}

bool
SlamKarto::getOdomPose(karto::Pose2& karto_pose, const ros::Time& t)
{
  // Get the robot's pose
  tf::Stamped<tf::Pose> ident (tf::Transform(tf::createQuaternionFromRPY(0,0,0),
                                           tf::Vector3(0,0,0)), t, base_frame_);
  tf::Stamped<tf::Transform> odom_pose;
  try
  {
    tf_.transformPose(odom_frame_, ident, odom_pose);
  }
  catch(tf::TransformException e)
  {
    ROS_WARN("Failed to compute odom pose, skipping scan (%s)", e.what());
    return false;
  }
  double yaw = tf::getYaw(odom_pose.getRotation());

  karto_pose = 
          karto::Pose2(odom_pose.getOrigin().x(),
                       odom_pose.getOrigin().y(),
                       yaw);
  return true;
}

void
SlamKarto::publishGraphVisualization()
{
  std::vector<Eigen::Vector2d> graph_nodes;
  
  std::vector<std::pair<Eigen::Vector2d,Eigen::Vector2d> > graph_edges;

  solver_->getGraph(graph_nodes, graph_edges);

  visualization_msgs::MarkerArray marray;

  visualization_msgs::Marker m;
  m.header.frame_id = "map";
  m.header.stamp = ros::Time::now();
  m.id = 0;
  m.ns = "karto";
  m.type = visualization_msgs::Marker::SPHERE;
  m.pose.position.x = 0.0;
  m.pose.position.y = 0.0;
  m.pose.position.z = 0.0;
  m.scale.x = 0.1;
  m.scale.y = 0.1;
  m.scale.z = 0.1;
  m.color.r = 1.0;
  m.color.g = 0;
  m.color.b = 0.0;
  m.color.a = 1.0;
  m.lifetime = ros::Duration(0);

  visualization_msgs::Marker edge;
  edge.header.frame_id = "map";
  edge.header.stamp = ros::Time::now();
  edge.action = visualization_msgs::Marker::ADD;
  edge.ns = "karto";
  edge.id = 0;
  edge.type = visualization_msgs::Marker::LINE_STRIP;
  edge.scale.x = 0.1;
  edge.scale.y = 0.1;
  edge.scale.z = 0.1;
  edge.color.a = 1.0;
  edge.color.r = 0.0;
  edge.color.g = 0.0;
  edge.color.b = 1.0;

  m.action = visualization_msgs::Marker::ADD;
  
  uint id = 0;
  
  for (uint i=0; i < graph_nodes.size(); i++) 
  {
    m.id = id;
    m.pose.position.x = graph_nodes[i](0);
    m.pose.position.y = graph_nodes[i](1);
    marray.markers.push_back(visualization_msgs::Marker(m));
    id++;
  }

  for (uint i=0; i < graph_edges.size(); i++) 
  {

    geometry_msgs::Point p;
    
    p.x = graph_edges[i].first(0);
    
    p.y = graph_edges[i].first(1);
    
    edge.points.push_back(p);
    
    p.x = graph_edges[i].second(0);
    
    p.y = graph_edges[i].second(1);
    
    edge.points.push_back(p);
    
    edge.id = id;

    marray.markers.push_back(visualization_msgs::Marker(edge));

    id++;
  }

  m.action = visualization_msgs::Marker::DELETE;
  
  for (; id < marker_count_; id++) 
  {
    m.id = id;
    marray.markers.push_back(visualization_msgs::Marker(m));
  }

  marker_count_ = marray.markers.size();

  marker_publisher_.publish(marray);

}

void
SlamKarto::laserCallback(const sensor_msgs::LaserScan::ConstPtr& scan)
{
  laser_count_++;
  if ((laser_count_ % throttle_scans_) != 0)
    return;

  static ros::Time last_map_update(0,0);

  // Check whether we know about this laser yet
  karto::LaserRangeFinder* laser = getLaser(scan);

  if(!laser)
  {
    ROS_WARN("Failed to create laser device for %s; discarding scan",
	     scan->header.frame_id.c_str());
    return;
  }

  karto::Pose2 odom_pose;
  if(addScan(laser, scan, odom_pose))
  {
    ROS_DEBUG("added scan at pose: %.3f %.3f %.3f", 
              odom_pose.GetX(),
              odom_pose.GetY(),
              odom_pose.GetHeading());

    publishGraphVisualization();

    if(!got_map_ || 
       (scan->header.stamp - last_map_update) > map_update_interval_)
    {
      if(updateMap())
      {
        last_map_update = scan->header.stamp;
        got_map_ = true;
        ROS_DEBUG("Updated the map");
      }
    }
  }
}

bool
SlamKarto::updateMap()
{
  boost::mutex::scoped_lock lock(map_mutex_);

  karto::OccupancyGrid* occ_grid = 
          karto::OccupancyGrid::CreateFromScans(mapper_->GetAllProcessedScans(), resolution_);

  if(!occ_grid)
    return false;

  if(!got_map_) {
    map_.map.info.resolution = resolution_;
    map_.map.info.origin.position.x = 0.0;
    map_.map.info.origin.position.y = 0.0;
    map_.map.info.origin.position.z = 0.0;
    map_.map.info.origin.orientation.x = 0.0;
    map_.map.info.origin.orientation.y = 0.0;
    map_.map.info.origin.orientation.z = 0.0;
    map_.map.info.origin.orientation.w = 1.0;
  } 

  // Translate to ROS format
  kt_int32s width = occ_grid->GetWidth();
  kt_int32s height = occ_grid->GetHeight();
  karto::Vector2<kt_double> offset = occ_grid->GetCoordinateConverter()->GetOffset();

  if(map_.map.info.width != (unsigned int) width || 
     map_.map.info.height != (unsigned int) height ||
     map_.map.info.origin.position.x != offset.GetX() ||
     map_.map.info.origin.position.y != offset.GetY())
  {
    map_.map.info.origin.position.x = offset.GetX();
    map_.map.info.origin.position.y = offset.GetY();
    map_.map.info.width = width;
    map_.map.info.height = height;
    map_.map.data.resize(map_.map.info.width * map_.map.info.height);
  }

  for (kt_int32s y=0; y<height; y++)
  {
    for (kt_int32s x=0; x<width; x++) 
    {
      // Getting the value at position x,y
      kt_int8u value = occ_grid->GetValue(karto::Vector2<kt_int32s>(x, y));

      switch (value)
      {
        case karto::GridStates_Unknown:
          map_.map.data[MAP_IDX(map_.map.info.width, x, y)] = -1;
          break;
        case karto::GridStates_Occupied:
          map_.map.data[MAP_IDX(map_.map.info.width, x, y)] = 100;
          break;
        case karto::GridStates_Free:
          map_.map.data[MAP_IDX(map_.map.info.width, x, y)] = 0;
          break;
        default:
          ROS_WARN("Encountered unknown cell value at %d, %d", x, y);
          break;
      }
    }
  }
  
  // Set the header information on the map
  map_.map.header.stamp = ros::Time::now();
  map_.map.header.frame_id = map_frame_;

  sst_.publish(map_.map);
  sstm_.publish(map_.map.info);

  delete occ_grid;

  return true;
}

bool
SlamKarto::addScan(karto::LaserRangeFinder* laser,
		   const sensor_msgs::LaserScan::ConstPtr& scan, 
                   karto::Pose2& karto_pose)
{
  if(!getOdomPose(karto_pose, scan->header.stamp))
     return false;
  
  // Create a vector of doubles for karto
  std::vector<kt_double> readings;

  if (lasers_inverted_[scan->header.frame_id]) {
    for(std::vector<float>::const_reverse_iterator it = scan->ranges.rbegin();
      it != scan->ranges.rend();
      ++it)
    {
      readings.push_back(*it);
    }
  } else {
    for(std::vector<float>::const_iterator it = scan->ranges.begin();
      it != scan->ranges.end();
      ++it)
    {
      readings.push_back(*it);
    }
  }
  
  // create localized range scan
  karto::LocalizedRangeScan* range_scan = 
    new karto::LocalizedRangeScan(laser->GetName(), readings);
  range_scan->SetOdometricPose(karto_pose);
  range_scan->SetCorrectedPose(karto_pose);

  // Add the localized range scan to the mapper
  bool processed;
  if((processed = mapper_->Process(range_scan)))
  {
    //std::cout << "Pose: " << range_scan->GetOdometricPose() << " Corrected Pose: " << range_scan->GetCorrectedPose() << std::endl;
    
    karto::Pose2 corrected_pose = range_scan->GetCorrectedPose();

    // Compute the map->odom transform
    tf::Stamped<tf::Pose> odom_to_map;
    try
    {
      tf_.transformPose(odom_frame_,tf::Stamped<tf::Pose> (tf::Transform(tf::createQuaternionFromRPY(0, 0, corrected_pose.GetHeading()),
                                                                    tf::Vector3(corrected_pose.GetX(), corrected_pose.GetY(), 0.0)).inverse(),
                                                                    scan->header.stamp, base_frame_),odom_to_map);
    }
    catch(tf::TransformException e)
    {
      ROS_ERROR("Transform from base_link to odom failed\n");
      odom_to_map.setIdentity();
    }

    map_to_odom_mutex_.lock();
    map_to_odom_ = tf::Transform(tf::Quaternion( odom_to_map.getRotation() ),
                                 tf::Point(      odom_to_map.getOrigin() ) ).inverse();
    map_to_odom_mutex_.unlock();


    // Add the localized range scan to the dataset (for memory management)
    dataset_->Add(range_scan);
  }
  else
    delete range_scan;

  return processed;
}

bool 
SlamKarto::mapCallback(nav_msgs::GetMap::Request  &req,
                       nav_msgs::GetMap::Response &res)
{
  boost::mutex::scoped_lock lock(map_mutex_);
  if(got_map_ && map_.map.info.width && map_.map.info.height)
  {
    res = map_;
    return true;
  }
  else
    return false;
}

int
main(int argc, char** argv)
{
  ros::init(argc, argv, "slam_karto_g2o");

  SlamKarto kn;

  ros::spin();

  return 0;
}