intensity_filter.h

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#ifndef LASER_SCAN_INTENSITY_FILTER_H
#define LASER_SCAN_INTENSITY_FILTER_H

#include "filters/filter_base.h"
#include "sensor_msgs/LaserScan.h"

namespace laser_filters
{

class LaserScanIntensityFilter : public filters::FilterBase<sensor_msgs::LaserScan>
{
public:

  double lower_threshold_ ;
  double upper_threshold_ ;
  int disp_hist_ ;

  bool configure()
  {
    lower_threshold_ = 8000.0;
    upper_threshold_ = 100000.0;
    disp_hist_ = 1;
    getParam("lower_threshold", lower_threshold_);
    getParam("upper_threshold", upper_threshold_) ;
    getParam("disp_histogram",  disp_hist_) ;

    return true;
  }

  virtual ~LaserScanIntensityFilter()
  { 

  }

  bool update(const sensor_msgs::LaserScan& input_scan, sensor_msgs::LaserScan& filtered_scan)
  {
    const double hist_max = 4*12000.0 ;
    const int num_buckets = 24 ;
    int histogram[num_buckets] ;
    for (int i=0; i < num_buckets; i++)
      histogram[i] = 0 ;

    filtered_scan = input_scan ;

    for (unsigned int i=0; 
         i < input_scan.ranges.size() && i < input_scan.intensities.size(); 
         i++) // Need to check ever reading in the current scan
    {
      if (filtered_scan.intensities[i] <= lower_threshold_ ||                           // Is this reading below our lower threshold?
          filtered_scan.intensities[i] >= upper_threshold_)                             // Is this reading above our upper threshold?
      {      

        filtered_scan.ranges[i] = input_scan.range_max + 1.0 ;                           // If so, then make it a value bigger than the max range
      }

      int cur_bucket = (int) ((filtered_scan.intensities[i]/hist_max)*num_buckets) ;
      if (cur_bucket >= num_buckets-1)
        cur_bucket = num_buckets-1 ;
      histogram[cur_bucket]++ ;
    }

    if (disp_hist_ > 0)                                                                 // Display Histogram
    {
      printf("********** SCAN **********\n") ;
      for (int i=0; i < num_buckets; i++)
      {
        printf("%u - %u: %u\n", (unsigned int) hist_max/num_buckets*i,
                                (unsigned int) hist_max/num_buckets*(i+1),
                                histogram[i]) ;
      }
    }
    return true;
  }
} ;

}

#endif // LASER_SCAN_INTENSITY_FILTER_H