icp.h

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#ifndef _ICP_H_
#define _ICP_H_
 
#include <gmapping/utils/point.h>
#include <utility>
#include <list>
#include <vector>
 
namespace GMapping{
typedef std::pair<Point,Point> PointPair;
 
template <typename PointPairContainer>
double icpStep(OrientedPoint & retval, const PointPairContainer& container){
        typedef typename PointPairContainer::const_iterator ContainerIterator;
        PointPair mean=std::make_pair(Point(0.,0.), Point(0.,0.));
        int size=0;
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                mean.first=mean.first+it->first;
                mean.second=mean.second+it->second;
                size++;
        }
        mean.first=mean.first*(1./size);
        mean.second=mean.second*(1./size);
        double sxx=0, sxy=0, syx=0, syy=0;
        
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                PointPair mf=std::make_pair(it->first-mean.first, it->second-mean.second);
                sxx+=mf.first.x*mf.second.x;
                sxy+=mf.first.x*mf.second.y;
                syx+=mf.first.y*mf.second.x;
                syy+=mf.first.y*mf.second.y;
        }
        retval.theta=atan2(sxy-syx, sxx+sxy);
        double s=sin(retval.theta), c=cos(retval.theta);
        retval.x=mean.second.x-(c*mean.first.x-s*mean.first.y);
        retval.y=mean.second.y-(s*mean.first.x+c*mean.first.y);
        
        double error=0;
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                Point delta(
                        c*it->first.x-s*it->first.y+retval.x-it->second.x, s*it->first.x+c*it->first.y+retval.y-it->second.y);
                error+=delta*delta;
        }
        return error;   
}
 
template <typename PointPairContainer>
double icpNonlinearStep(OrientedPoint & retval, const PointPairContainer& container){
        typedef typename PointPairContainer::const_iterator ContainerIterator;
        PointPair mean=std::make_pair(Point(0.,0.), Point(0.,0.));
        int size=0;
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                mean.first=mean.first+it->first;
                mean.second=mean.second+it->second;
                size++;
        }
        
        mean.first=mean.first*(1./size);
        mean.second=mean.second*(1./size);
        
        double ms=0,mc=0;
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                PointPair mf=std::make_pair(it->first-mean.first, it->second-mean.second);
                double  dalpha=atan2(mf.second.y, mf.second.x) - atan2(mf.first.y, mf.first.x);
                double gain=sqrt(mean.first*mean.first);
                ms+=gain*sin(dalpha);
                mc+=gain*cos(dalpha);
        }
        retval.theta=atan2(ms, mc);
        double s=sin(retval.theta), c=cos(retval.theta);
        retval.x=mean.second.x-(c*mean.first.x-s*mean.first.y);
        retval.y=mean.second.y-(s*mean.first.x+c*mean.first.y);
        
        double error=0;
        for (ContainerIterator it=container.begin(); it!=container.end(); it++){
                Point delta(
                        c*it->first.x-s*it->first.y+retval.x-it->second.x, s*it->first.x+c*it->first.y+retval.y-it->second.y);
                error+=delta*delta;
        }
        return error;   
}
 
}//end namespace
 
#endif