footprint_filter.h

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#ifndef LASER_SCAN_FOOTPRINT_FILTER_H
#define LASER_SCAN_FOOTPRINT_FILTER_H

#include "filters/filter_base.h"
#include "sensor_msgs/LaserScan.h"
#include "tf/transform_listener.h"
#include "sensor_msgs/PointCloud.h"
#include "ros/ros.h"
#include "laser_geometry/laser_geometry.h"

namespace laser_filters
{

class LaserScanFootprintFilter : public filters::FilterBase<sensor_msgs::LaserScan>
{
public:
  LaserScanFootprintFilter(): up_and_running_(false) {}

  bool configure()
  {
    if(!getParam("inscribed_radius", inscribed_radius_))
    {
      ROS_ERROR("LaserScanFootprintFilter needs inscribed_radius to be set");
      return false;
    }
    return true;
  }

  virtual ~LaserScanFootprintFilter()
  {

  }

  bool update(const sensor_msgs::LaserScan& input_scan, sensor_msgs::LaserScan& filtered_scan)
  {
    filtered_scan = input_scan ;
    sensor_msgs::PointCloud laser_cloud;

    try{
      projector_.transformLaserScanToPointCloud("base_link", input_scan, laser_cloud, tf_);
    }
    catch(tf::TransformException& ex){
      if(up_and_running_){
        ROS_WARN_THROTTLE(1, "Dropping Scan: Transform unavailable %s", ex.what());
      }
      else {
        ROS_INFO_THROTTLE(.3, "Ignoring Scan: Waiting for TF");
      }
      return false;
    }

    int c_idx = indexChannel(laser_cloud);

    if (c_idx == -1 || laser_cloud.channels[c_idx].values.size () == 0){
      ROS_ERROR("We need an index channel to be able to filter out the footprint");
      return false;
    }

    for (unsigned int i=0; i < laser_cloud.points.size(); i++)
    {
      if (inFootprint(laser_cloud.points[i])){
        int index = laser_cloud.channels[c_idx].values[i];
        filtered_scan.ranges[index] = std::numeric_limits<float>::quiet_NaN();
      }
    }

    up_and_running_ = true;
    return true;
  }

  int indexChannel(const sensor_msgs::PointCloud& scan_cloud){
      int c_idx = -1;
      for (unsigned int d = 0; d < scan_cloud.channels.size (); d++)
      {
        if (scan_cloud.channels[d].name == "index")
        {
          c_idx = d;
          break;
        }
      }
      return c_idx;
  }

  bool inFootprint(const geometry_msgs::Point32& scan_pt){
    if(scan_pt.x < -1.0 * inscribed_radius_ || scan_pt.x > inscribed_radius_ || scan_pt.y < -1.0 * inscribed_radius_ || scan_pt.y > inscribed_radius_)
      return false;
    return true;
  }

private:
  tf::TransformListener tf_;
  laser_geometry::LaserProjection projector_;
  double inscribed_radius_;
  bool up_and_running_;
} ;

}

#endif // LASER_SCAN_FOOTPRINT_FILTER_H