source: trunk/src/Detection/detection.cc @ 482

// -----------------------------------------------------------------------
// detection.cc : Member functions for the Detection class.
// -----------------------------------------------------------------------
// Copyright (C) 2006, Matthew Whiting, ATNF
//
// This program is free software; you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at your
// option) any later version.
//
// Duchamp is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License
// along with Duchamp; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
//
// Correspondence concerning Duchamp may be directed to:
//    Internet email: Matthew.Whiting [at] atnf.csiro.au
//    Postal address: Dr. Matthew Whiting
//                    Australia Telescope National Facility, CSIRO
//                    PO Box 76
//                    Epping NSW 1710
//                    AUSTRALIA
// -----------------------------------------------------------------------
#include <iostream>
#include <iomanip>
#include <vector>
#include <string>
#include <wcslib/wcs.h>
#include <math.h>
#include <duchamp/duchamp.hh>
#include <duchamp/param.hh>
#include <duchamp/fitsHeader.hh>
#include <duchamp/Utils/utils.hh>
#include <duchamp/PixelMap/Voxel.hh>
#include <duchamp/PixelMap/Object3D.hh>
#include <duchamp/Detection/detection.hh>
#include <duchamp/Cubes/cubeUtils.hh>

using namespace PixelInfo;

namespace duchamp
{


  Detection::Detection()
  {
    this->flagWCS=false; 
    this->negSource = false; 
    this->flagText="";
    this->totalFlux = this->peakFlux = this->intFlux = 0.;
    this->centreType="centroid";
    this->id = -1;
    this->raS = this->decS = "";
    this->ra = this->dec = this->vel = 0.;
    this->raWidth = this->decWidth = 0.;
    this->majorAxis = this->minorAxis = this->posang = 0.;
    this->w20 = this->w50 = this->velWidth = 0.;
  }

  Detection::Detection(const Detection& d)
  {
    operator=(d);
  }

  Detection& Detection::operator= (const Detection& d)
  {
    if(this == &d) return *this;
    this->pixelArray   = d.pixelArray;
    this->xSubOffset   = d.xSubOffset;
    this->ySubOffset   = d.ySubOffset;
    this->zSubOffset   = d.zSubOffset;
    this->totalFlux    = d.totalFlux;
    this->intFlux      = d.intFlux;
    this->peakFlux     = d.peakFlux;
    this->xpeak        = d.xpeak;
    this->ypeak        = d.ypeak;
    this->zpeak        = d.zpeak;
    this->peakSNR      = d.peakSNR;
    this->xCentroid    = d.xCentroid;
    this->yCentroid    = d.yCentroid;
    this->zCentroid    = d.zCentroid;
    this->centreType   = d.centreType;
    this->negSource    = d.negSource;
    this->flagText     = d.flagText;
    this->id           = d.id;
    this->name         = d.name;
    this->flagWCS      = d.flagWCS;
    this->specOK       = d.specOK;
    this->raS          = d.raS;
    this->decS         = d.decS;
    this->ra           = d.ra;
    this->dec          = d.dec;
    this->raWidth      = d.raWidth;
    this->decWidth     = d.decWidth;
    this->majorAxis    = d.majorAxis;
    this->minorAxis    = d.minorAxis;
    this->posang       = d.posang;
    this->specUnits    = d.specUnits;
    this->fluxUnits    = d.fluxUnits;
    this->intFluxUnits = d.intFluxUnits;
    this->lngtype      = d.lngtype;
    this->lattype      = d.lattype;
    this->vel          = d.vel;
    this->velWidth     = d.velWidth;
    this->velMin       = d.velMin;
    this->velMax       = d.velMax;
    this->w20          = d.w20;
    this->v20min       = d.v20min;
    this->v20max       = d.v20max;
    this->w50          = d.w50;
    this->v50min       = d.v50min;
    this->v50max       = d.v50max;
    this->posPrec      = d.posPrec;
    this->xyzPrec      = d.xyzPrec;
    this->fintPrec     = d.fintPrec;
    this->fpeakPrec    = d.fpeakPrec;
    this->velPrec      = d.velPrec;
    this->snrPrec      = d.snrPrec;
    return *this;
  }

  //--------------------------------------------------------------------

  bool Detection::voxelListsMatch(std::vector<Voxel> voxelList)
  {
    /**
     *  A test to see whether there is a 1-1 correspondence between
     *  the given list of Voxels and the voxel positions contained in
     *  this Detection's pixel list. No testing of the fluxes of the
     *  Voxels is done.
     *
     * \param voxelList The std::vector list of Voxels to be tested.
     */

    bool listsMatch = true;
    // compare sizes
    listsMatch = listsMatch && (voxelList.size() == this->getSize());
    if(!listsMatch) return listsMatch;

    // make sure all Detection pixels are in voxel list
    listsMatch = listsMatch && this->voxelListCovered(voxelList);

    // make sure all voxels are in Detection
    for(int i=0;i<voxelList.size();i++)
      listsMatch = listsMatch && this->pixelArray.isInObject(voxelList[i]);

    return listsMatch;

  }
  //--------------------------------------------------------------------

  //--------------------------------------------------------------------

  bool Detection::voxelListCovered(std::vector<Voxel> voxelList)
  {
    /**
     *  A test to see whether the given list of Voxels contains each
     *  position in this Detection's pixel list. It does not look for
     *  a 1-1 correspondence: the given list can be a super-set of the
     *  Detection. No testing of the fluxes of the Voxels is done.
     *
     * \param voxelList The std::vector list of Voxels to be tested.
     */

    bool listsMatch = true;

    // make sure all Detection pixels are in voxel list
    int v1=0, mysize=this->getSize();
    while(listsMatch && v1<mysize){
      bool inList = false;
      int v2=0;
      Voxel test = this->getPixel(v1);
      while(!inList && v2<voxelList.size()){
        inList = inList || test.match(voxelList[v2]);
        v2++;
      }
      listsMatch = listsMatch && inList;
      v1++;
    }

    return listsMatch;

  }
  //--------------------------------------------------------------------

  void Detection::calcFluxes(std::vector<Voxel> voxelList)
  {
    /**
     *  A function that calculates total & peak fluxes (and the location
     *  of the peak flux) for a Detection.
     *
     *  \param fluxArray The array of flux values to calculate the
     *  flux parameters from.
     *  \param dim The dimensions of the flux array.
     */

    this->totalFlux = this->peakFlux = 0;
    this->xCentroid = this->yCentroid = this->zCentroid = 0.;

    // first check that the voxel list and the Detection's pixel list
    // have a 1-1 correspondence

    if(!this->voxelListCovered(voxelList)){
      duchampError("Detection::calcFluxes","Voxel list provided does not match");
      return;
    }

    for(int i=0;i<voxelList.size();i++) {
      if(this->pixelArray.isInObject(voxelList[i])){
        long x = voxelList[i].getX();
        long y = voxelList[i].getY();
        long z = voxelList[i].getZ();
        float f = voxelList[i].getF();
        this->totalFlux += f;
        this->xCentroid += x*f;
        this->yCentroid += y*f;
        this->zCentroid += z*f;
        if( (i==0) ||  //first time round
            (this->negSource&&(f<this->peakFlux)) || 
            (!this->negSource&&(f>this->peakFlux))   )
          {
            this->peakFlux = f;
            this->xpeak =    x;
            this->ypeak =    y;
            this->zpeak =    z;
          }
      }
    }

    this->xCentroid /= this->totalFlux;
    this->yCentroid /= this->totalFlux;
    this->zCentroid /= this->totalFlux;
  }
  //--------------------------------------------------------------------

  void Detection::calcFluxes(float *fluxArray, long *dim)
  {
    /**
     *  A function that calculates total & peak fluxes (and the location
     *  of the peak flux) for a Detection.
     *
     *  \param fluxArray The array of flux values to calculate the
     *  flux parameters from.
     *  \param dim The dimensions of the flux array.
     */

    this->totalFlux = this->peakFlux = 0;
    this->xCentroid = this->yCentroid = this->zCentroid = 0.;

    std::vector<Voxel> voxList = this->pixelArray.getPixelSet();
    std::vector<Voxel>::iterator vox=voxList.begin();
    for(;vox<voxList.end();vox++){

      long x=vox->getX();
      long y=vox->getY();
      long z=vox->getZ();
      long ind = vox->arrayIndex(dim);
      float f = fluxArray[ind];
      this->totalFlux += f;
      this->xCentroid += x*f;
      this->yCentroid += y*f;
      this->zCentroid += z*f;
      if( (vox==voxList.begin()) ||
          (this->negSource&&(f<this->peakFlux)) || 
          (!this->negSource&&(f>this->peakFlux))   )
        {
          this->peakFlux = f;
          this->xpeak = x;
          this->ypeak = y;
          this->zpeak = z;
        }
 
    }

    this->xCentroid /= this->totalFlux;
    this->yCentroid /= this->totalFlux;
    this->zCentroid /= this->totalFlux;
  }
  //--------------------------------------------------------------------

  void Detection::calcWCSparams(FitsHeader &head)
  {
    /**
     *  Use the input wcs to calculate the position and velocity 
     *    information for the Detection.
     *  Quantities calculated:
     *  <ul><li> RA: ra [deg], ra (string), ra width.
     *      <li> Dec: dec [deg], dec (string), dec width.
     *      <li> Vel: vel [km/s], min & max vel, vel width.
     *      <li> coord type for all three axes, nuRest, 
     *      <li> name (IAU-style, in equatorial or Galactic) 
     *  </ul>
     *
     *  Note that the regular parameters are NOT recalculated!
     *
     *  \param head FitsHeader object that contains the WCS information.
     */

    if(head.isWCS()){

      double *pixcrd = new double[15];
      double *world  = new double[15];
      /*
        define a five-point array in 3D:
        (x,y,z), (x,y,z1), (x,y,z2), (x1,y1,z), (x2,y2,z)
        [note: x = central point, x1 = minimum x, x2 = maximum x etc.]
        and convert to world coordinates.   
      */
      pixcrd[0]  = pixcrd[3] = pixcrd[6] = this->getXcentre();
      pixcrd[9]  = this->getXmin()-0.5;
      pixcrd[12] = this->getXmax()+0.5;
      pixcrd[1]  = pixcrd[4] = pixcrd[7] = this->getYcentre();
      pixcrd[10] = this->getYmin()-0.5;
      pixcrd[13] = this->getYmax()+0.5;
      pixcrd[2] = pixcrd[11] = pixcrd[14] = this->getZcentre();
      pixcrd[5] = this->getZmin();
      pixcrd[8] = this->getZmax();
      int flag = head.pixToWCS(pixcrd, world, 5);
      delete [] pixcrd;
      if(flag!=0) duchampError("calcWCSparams",
                               "Error in calculating the WCS for this object.\n");
      else{

        // world now has the WCS coords for the five points 
        //    -- use this to work out WCS params
  
        this->specOK = head.canUseThirdAxis();
        this->lngtype = head.WCS().lngtyp;
        this->lattype = head.WCS().lattyp;
        this->specUnits = head.getSpectralUnits();
        this->fluxUnits = head.getFluxUnits();
        // if fluxUnits are eg. Jy/beam, make intFluxUnits = Jy km/s
        this->intFluxUnits = head.getIntFluxUnits();
        this->ra   = world[0];
        this->dec  = world[1];
        this->raS  = decToDMS(this->ra, this->lngtype);
        this->decS = decToDMS(this->dec,this->lattype);
        this->raWidth = angularSeparation(world[9],world[1],
                                          world[12],world[1]) * 60.;
        this->decWidth  = angularSeparation(world[0],world[10],
                                            world[0],world[13]) * 60.;

        Object2D spatMap = this->pixelArray.getSpatialMap();
        std::pair<double,double> axes = spatMap.getPrincipleAxes();
        this->majorAxis = std::max(axes.first,axes.second) * head.getAvPixScale();
        this->minorAxis = std::min(axes.first,axes.second) * head.getAvPixScale();
        this->posang = spatMap.getPositionAngle() * 180. / M_PI;

        this->name = head.getIAUName(this->ra, this->dec);
        this->vel    = head.specToVel(world[2]);
        this->velMin = head.specToVel(world[5]);
        this->velMax = head.specToVel(world[8]);
        this->velWidth = fabs(this->velMax - this->velMin);

        //      this->calcIntegFlux(fluxArray,dim,head);
    
        this->flagWCS = true;
      }
      delete [] world;

    }
  }
  //--------------------------------------------------------------------

  void Detection::calcIntegFlux(std::vector<Voxel> voxelList, FitsHeader &head)
  {
    /**
     *  Uses the input WCS to calculate the velocity-integrated flux, 
     *   putting velocity in units of km/s.
     *  The fluxes used are taken from the Voxels, rather than an
     *   array of flux values.
     *  Integrates over full spatial and velocity range as given 
     *   by the extrema calculated by calcWCSparams.
     *
     *  If the flux units end in "/beam" (eg. Jy/beam), then the flux is
     *  corrected by the beam size (in pixels). This is done by
     *  multiplying the integrated flux by the number of spatial pixels,
     *  and dividing by the beam size in pixels (e.g. Jy/beam * pix /
     *  pix/beam --> Jy)
     *
     *  \param voxelList The list of Voxels with flux information
     *  \param head FitsHeader object that contains the WCS information.
     */

    const int border = 1;

    if(!this->voxelListCovered(voxelList)){
      duchampError("Detection::calcIntegFlux","Voxel list provided does not match");
      return;
    }

    if(head.getNumAxes() > 2) {

      // include one pixel either side in each direction
      long xsize = (this->getXmax()-this->getXmin()+border*2+1);
      long ysize = (this->getYmax()-this->getYmin()+border*2+1);
      long zsize = (this->getZmax()-this->getZmin()+border*2+1); 
      long size = xsize*ysize*zsize;
      std::vector <bool> isObj(size,false);
      double *localFlux = new double[size];
      for(int i=0;i<size;i++) localFlux[i]=0.;

      for(int i=0;i<voxelList.size();i++){
        if(this->pixelArray.isInObject(voxelList[i])){
          long x = voxelList[i].getX();
          long y = voxelList[i].getY();
          long z = voxelList[i].getZ();
          long pos = (x-this->getXmin()+border) + (y-this->getYmin()+border)*xsize
            + (z-this->getZmin()+border)*xsize*ysize;
          localFlux[pos] = voxelList[i].getF();
          isObj[pos] = true;
        }
      }
  
      // work out the WCS coords for each pixel
      double *world  = new double[size];
      double xpt,ypt,zpt;
      for(int i=0;i<xsize*ysize*zsize;i++){
        xpt = double( this->getXmin() - border + i%xsize );
        ypt = double( this->getYmin() - border + (i/xsize)%ysize );
        zpt = double( this->getZmin() - border + i/(xsize*ysize) );
        world[i] = head.pixToVel(xpt,ypt,zpt);
      }

      double integrated = 0.;
      for(int pix=0; pix<xsize*ysize; pix++){ // loop over each spatial pixel.
        for(int z=0; z<zsize; z++){
          int pos =  z*xsize*ysize + pix;
          if(isObj[pos]){ // if it's an object pixel...
            double deltaVel;
            if(z==0) 
              deltaVel = (world[pos+xsize*ysize] - world[pos]);
            else if(z==(zsize-1)) 
              deltaVel = (world[pos] - world[pos-xsize*ysize]);
            else 
              deltaVel = (world[pos+xsize*ysize] - world[pos-xsize*ysize]) / 2.;
            integrated += localFlux[pos] * fabs(deltaVel);
          }
        }
      }
      this->intFlux = integrated;

      delete [] world;
      delete [] localFlux;

      calcVelWidths(voxelList,head);

    }
    else // in this case there is just a 2D image.
      this->intFlux = this->totalFlux;

    if(head.isWCS()){
      // correct for the beam size if the flux units string ends in "/beam"
      if(head.needBeamSize()) this->intFlux  /= head.getBeamSize();
    }

  }
  //--------------------------------------------------------------------

  void Detection::calcIntegFlux(float *fluxArray, long *dim, FitsHeader &head)
  {
    /**
     *  Uses the input WCS to calculate the velocity-integrated flux, 
     *   putting velocity in units of km/s.
     *  Integrates over full spatial and velocity range as given 
     *   by the extrema calculated by calcWCSparams.
     *
     *  If the flux units end in "/beam" (eg. Jy/beam), then the flux is
     *  corrected by the beam size (in pixels). This is done by
     *  multiplying the integrated flux by the number of spatial pixels,
     *  and dividing by the beam size in pixels (e.g. Jy/beam * pix /
     *  pix/beam --> Jy)
     *
     *  \param fluxArray The array of flux values.
     *  \param dim The dimensions of the flux array.
     *  \param head FitsHeader object that contains the WCS information.
     */

    if(head.getNumAxes() > 2) {

      // include one pixel either side in each direction
      long xsize = (this->getXmax()-this->getXmin()+3);
      long ysize = (this->getYmax()-this->getYmin()+3);
      long zsize = (this->getZmax()-this->getZmin()+3); 
      long size = xsize*ysize*zsize;
      std::vector <bool> isObj(size,false);
      double *localFlux = new double[size];
      for(int i=0;i<size;i++) localFlux[i]=0.;
      // work out which pixels are object pixels
      for(int m=0; m<this->pixelArray.getNumChanMap(); m++){
        ChanMap tempmap = this->pixelArray.getChanMap(m);
        long z = this->pixelArray.getChanMap(m).getZ();
        for(int s=0; s<this->pixelArray.getChanMap(m).getNumScan(); s++){
          long y = this->pixelArray.getChanMap(m).getScan(s).getY();
          for(long x=this->pixelArray.getChanMap(m).getScan(s).getX(); 
              x<=this->pixelArray.getChanMap(m).getScan(s).getXmax(); 
              x++){
            long pos = (x-this->getXmin()+1) + (y-this->getYmin()+1)*xsize
              + (z-this->getZmin()+1)*xsize*ysize;
            localFlux[pos] = fluxArray[x + y*dim[0] + z*dim[0]*dim[1]];
            isObj[pos] = true;
          }
        }
      }
  
      // work out the WCS coords for each pixel
      double *world  = new double[size];
      double xpt,ypt,zpt;
      for(int i=0;i<xsize*ysize*zsize;i++){
        xpt = double( this->getXmin() -1 + i%xsize );
        ypt = double( this->getYmin() -1 + (i/xsize)%ysize );
        zpt = double( this->getZmin() -1 + i/(xsize*ysize) );
        world[i] = head.pixToVel(xpt,ypt,zpt);
      }

      double integrated = 0.;
      for(int pix=0; pix<xsize*ysize; pix++){ // loop over each spatial pixel.
        for(int z=0; z<zsize; z++){
          int pos =  z*xsize*ysize + pix;
          if(isObj[pos]){ // if it's an object pixel...
            double deltaVel;
            if(z==0) 
              deltaVel = (world[pos+xsize*ysize] - world[pos]);
            else if(z==(zsize-1)) 
              deltaVel = (world[pos] - world[pos-xsize*ysize]);
            else 
              deltaVel = (world[pos+xsize*ysize] - world[pos-xsize*ysize]) / 2.;
            integrated += localFlux[pos] * fabs(deltaVel);
          }
        }
      }
      this->intFlux = integrated;

      delete [] world;
      delete [] localFlux;

      calcVelWidths(fluxArray, dim, head);

    }
    else // in this case there is just a 2D image.
      this->intFlux = this->totalFlux;

    if(head.isWCS()){
      // correct for the beam size if the flux units string ends in "/beam"
      if(head.needBeamSize()) this->intFlux  /= head.getBeamSize();
    }

  }
  //--------------------------------------------------------------------

  void Detection::calcVelWidths(std::vector<Voxel> voxelList, FitsHeader &head)
  {
    /**
     * Calculates the widths of the detection at 20% and 50% of the
     * peak integrated flux. The procedure is as follows: first
     * generate an integrated flux spectrum (using all given voxels
     * that lie in the object's spatial map); find the peak; starting
     * at the spectral edges of the detection, move in or out until
     * you reach the 20% or 50% peak flux level. Linear interpolation
     * between points is done.
     *
     *  \param voxelList The list of Voxels with flux information
     *  \param head FitsHeader object that contains the WCS information.
     */

    const int border = 1;
    long zsize = (this->getZmax()-this->getZmin()+border*2+1); 
    double xpt = double(this->getXcentre()); 
    double ypt = double(this->getYcentre());
    double zpt;

    float *intSpec = new float[zsize];
    for(int i=0;i<zsize;i++) intSpec[i]=0;
       
    Object2D spatMap = this->pixelArray.getSpatialMap();
    for(int s=0;s<spatMap.getNumScan();s++){
      for(int i=0;i<voxelList.size();i++){
        if(spatMap.isInObject(voxelList[i])){
          if(voxelList[i].getZ()>=this->getZmin()-border && 
             voxelList[i].getZ()<=this->getZmax()+border)
            intSpec[voxelList[i].getZ()-this->getZmin()+1] += voxelList[i].getF();
        }
      }
    }
    
    std::vector<std::pair<int,float> > goodPix;
    float peak;
    int peakLoc;
    for(int z=0;z<zsize;z++) {
      if(z==0 || peak<intSpec[z]){
        peak = intSpec[z];
        peakLoc = z;
      }
      goodPix.push_back(std::pair<int,float>(z,intSpec[z]));
    }

    // finding the 20% & 50% points.  Start at the velmin & velmax
    //  points. Then, if the int flux there is above the 20%/50%
    //  limit, go out, otherwise go in. This is to deal with the
    //  problems from double peaked sources.

    int z;
    bool goLeft;
    z=border;
    goLeft = intSpec[z]>peak*0.5;
    if(goLeft) while(z>0 && intSpec[z]>peak*0.5) z--;
    else       while(z<peakLoc && intSpec[z]<peak*0.5) z++;
    if(z==0) this->v50min = this->velMin;
    else{
      if(goLeft) zpt = z + (peak*0.5-intSpec[z])/(intSpec[z+1]-intSpec[z]) + this->getZmin() - border;
      else       zpt = z - (peak*0.5-intSpec[z])/(intSpec[z-1]-intSpec[z]) + this->getZmin() - border;
      this->v50min = head.pixToVel(xpt,ypt,zpt);
    }
    z=this->getZmax()-this->getZmin();
    goLeft = intSpec[z]<peak*0.5;
    if(goLeft) while(z>peakLoc && intSpec[z]<peak*0.5) z--;
    else       while(z<zsize && intSpec[z]>peak*0.5) z++;
    if(z==zsize) this->v50max = this->velMax;
    else{
      if(goLeft) zpt = z + (peak*0.5-intSpec[z])/(intSpec[z+1]-intSpec[z]) + this->getZmin() - border;
      else       zpt = z - (peak*0.5-intSpec[z])/(intSpec[z-1]-intSpec[z]) + this->getZmin() - border;
      this->v50max = head.pixToVel(xpt,ypt,zpt);
    }
    z=border;
    goLeft = intSpec[z]>peak*0.5;
    if(goLeft) while(z>0 && intSpec[z]>peak*0.2) z--;
    else       while(z<peakLoc && intSpec[z]<peak*0.2) z++;
    if(z==0) this->v20min = this->velMin;
    else{
      if(goLeft) zpt = z + (peak*0.2-intSpec[z])/(intSpec[z+1]-intSpec[z]) + this->getZmin() - border;
      else       zpt = z - (peak*0.2-intSpec[z])/(intSpec[z-1]-intSpec[z]) + this->getZmin() - border;
      this->v20min = head.pixToVel(xpt,ypt,zpt);
    }
    z=this->getZmax()-this->getZmin();
    goLeft = intSpec[z]<peak*0.5;
    if(goLeft) while(z>peakLoc && intSpec[z]<peak*0.2) z--;
    else       while(z<zsize && intSpec[z]>peak*0.2) z++;
    if(z==zsize) this->v20max = this->velMax;
    else{
      if(goLeft) zpt = z + (peak*0.2-intSpec[z])/(intSpec[z+1]-intSpec[z]) + this->getZmin() - border;
      else       zpt = z - (peak*0.2-intSpec[z])/(intSpec[z-1]-intSpec[z]) + this->getZmin() - border;
      this->v20max = head.pixToVel(xpt,ypt,zpt);
    }

    this->w20 = fabs(this->v20min - this->v20max);
    this->w50 = fabs(this->v50min - this->v50max);

    delete [] intSpec;

  }

  //--------------------------------------------------------------------

  void Detection::calcVelWidths(float *fluxArray, long *dim, FitsHeader &head)
  {
    /**
     * Calculates the widths of the detection at 20% and 50% of the
     * peak integrated flux. The procedure is as follows: first
     * generate an integrated flux spectrum (summing each spatial
     * pixel's spectrum); find the peak; starting at the spectral
     * edges of the detection, move in or out until you reach the 20%
     * or 50% peak flux level. Linear interpolation between points is
     * done. 
     *
     *  \param fluxArray The array of flux values.
     *  \param dim The dimensions of the flux array.
     *  \param head FitsHeader object that contains the WCS information.
     */

    if(dim[2] > 2){

      double xpt = double(this->getXcentre()); 
      double ypt = double(this->getYcentre());
      double zpt;

      float *intSpec = new float[dim[2]];
      bool *mask = new bool[dim[0]*dim[1]*dim[2]]; 
      for(int i=0;i<dim[0]*dim[1]*dim[2];i++) mask[i] = true;
      getIntSpec(*this,fluxArray,dim,mask,1.,intSpec);

      std::vector<std::pair<int,float> > goodPix;
      float peak;
      int peakLoc;
      for(int z=this->getZmin();z<=this->getZmax();z++) {
        if(z==this->getZmin() || peak<intSpec[z]){
          peak = intSpec[z];
          peakLoc = z;
        }
        goodPix.push_back(std::pair<int,float>(z,intSpec[z]));
      }

      // finding the 20% & 50% points.  Start at the velmin & velmax
      //  points. Then, if the int flux there is above the 20%/50%
      //  limit, go out, otherwise go in. This is to deal with the
      //  problems from double- (or multi-) peaked sources.

      int z;
      bool goLeft;
      z=this->getZmin();
      goLeft = intSpec[z]>peak*0.5;
      if(goLeft) while(z>0 && intSpec[z]>peak*0.5) z--;
      else       while(z<peakLoc && intSpec[z]<peak*0.5) z++;
      if(z==0) this->v50min = this->velMin;
      else{
        if(goLeft) zpt = z + (peak*0.5-intSpec[z])/(intSpec[z+1]-intSpec[z]);
        else       zpt = z - (peak*0.5-intSpec[z])/(intSpec[z-1]-intSpec[z]);
        this->v50min = head.pixToVel(xpt,ypt,zpt);
      }
      z=this->getZmax();
      goLeft = intSpec[z]<peak*0.5;
      if(goLeft) while(z>peakLoc && intSpec[z]<peak*0.5) z--;
      else       while(z<dim[2] && intSpec[z]>peak*0.5) z++;
      if(z==dim[2]) this->v50max = this->velMax;
      else{
        if(goLeft) zpt = z + (peak*0.5-intSpec[z])/(intSpec[z+1]-intSpec[z]);
        else       zpt = z - (peak*0.5-intSpec[z])/(intSpec[z-1]-intSpec[z]);
        this->v50max = head.pixToVel(xpt,ypt,zpt);
      }
      z=this->getZmin();
      goLeft = intSpec[z]>peak*0.5;
      if(goLeft) while(z>0 && intSpec[z]>peak*0.2) z--;
      else       while(z<peakLoc && intSpec[z]<peak*0.2) z++;
      if(z==0) this->v20min = this->velMin;
      else{
        if(goLeft) zpt = z + (peak*0.2-intSpec[z])/(intSpec[z+1]-intSpec[z]);
        else       zpt = z - (peak*0.2-intSpec[z])/(intSpec[z-1]-intSpec[z]);
        this->v20min = head.pixToVel(xpt,ypt,zpt);
      }
      z=this->getZmax();
      goLeft = intSpec[z]<peak*0.5;
      if(goLeft) while(z>peakLoc && intSpec[z]<peak*0.2) z--;
      else       while(z<dim[2] && intSpec[z]>peak*0.2) z++;
      if(z==dim[2]) this->v20max = this->velMax;
      else{
        if(goLeft) zpt = z + (peak*0.2-intSpec[z])/(intSpec[z+1]-intSpec[z]);
        else       zpt = z - (peak*0.2-intSpec[z])/(intSpec[z-1]-intSpec[z]);
        this->v20max = head.pixToVel(xpt,ypt,zpt);
      }

      delete [] intSpec;
      delete [] mask;

    }
    else{
      this->v50min = this->v20min = this->velMin;
      this->v50max = this->v20max = this->velMax;
    }

    this->w20 = fabs(this->v20min - this->v20max);
    this->w50 = fabs(this->v50min - this->v50max);

  }
  //--------------------------------------------------------------------

  Detection operator+ (Detection lhs, Detection rhs)
  {
    /**
     *  Combines two objects by adding all the pixels using the Object3D
     *  operator.
     *
     *  The pixel parameters are recalculated in the process (equivalent
     *  to calling pixels().calcParams()), but WCS parameters are not.
     */
    Detection output = lhs;
    output.pixelArray = lhs.pixelArray + rhs.pixelArray;
    return output;
  }
  //--------------------------------------------------------------------

  void Detection::setOffsets(Param &par)
  {
    /**
     * This function stores the values of the offsets for each cube axis.
     * The offsets are the starting values of the cube axes that may differ from
     *  the default value of 0 (for instance, if a subsection is being used).
     * The values will be used when the detection is outputted.
     */
    this->xSubOffset = par.getXOffset();
    this->ySubOffset = par.getYOffset();
    this->zSubOffset = par.getZOffset();
  }
  //--------------------------------------------------------------------

  bool Detection::hasEnoughChannels(int minNumber)
  {
    /**
     * A function to determine if the Detection has enough
     * contiguous channels to meet the minimum requirement
     * given as the argument. 
     * \param minNumber How many channels is the minimum acceptable number?
     * \return True if there is at least one occurence of minNumber consecutive
     * channels present to return true. False otherwise.
     */

    // Preferred method -- need a set of minNumber consecutive channels present.
    this->pixelArray.order();
    int numChannels = 0;
    bool result = false;
    int size = this->pixelArray.getNumChanMap();
    if(size>0) numChannels++;
    if( numChannels >= minNumber) result = true;
    for(int i=1;(i<size && !result);i++) {
      if( (this->pixelArray.getZ(i) - this->pixelArray.getZ(i-1)) == 1) 
        numChannels++;
      else if( (this->pixelArray.getZ(i) - this->pixelArray.getZ(i-1)) >= 2) 
        numChannels = 1;

      if( numChannels >= minNumber) result = true;
    }
    return result;
  
  }
  //--------------------------------------------------------------------

  std::vector<int> Detection::getVertexSet()
  {
    /**
     * Gets a list of points being the end-points of 1-pixel long
     * segments drawing a border around the spatial extend of a
     * detection. The vector is a series of 4 integers, being: x_0,
     * y_0, x_1, y_1.
     * \return The vector of vertex positions.
     */
    std::vector<int> vertexSet;

    int xmin = this->getXmin() - 1;
    int xmax = this->getXmax() + 1;
    int ymin = this->getYmin() - 1;
    int ymax = this->getYmax() + 1;
    int xsize = xmax - xmin + 1;
    int ysize = ymax - ymin + 1;

    std::vector<Voxel> voxlist = this->pixelArray.getPixelSet();
    std::vector<bool> isObj(xsize*ysize,false);
    for(int i=0;i<voxlist.size();i++){
      int pos = (voxlist[i].getX()-xmin) + 
        (voxlist[i].getY()-ymin)*xsize;
      isObj[pos] = true;
    }
    voxlist.clear();
    
    for(int x=xmin; x<=xmax; x++){
      // for each column...
      for(int y=ymin+1;y<=ymax;y++){
        int current  = (y-ymin)*xsize + x-xmin;
        int previous = (y-ymin-1)*xsize + x-xmin;
        if((isObj[current]&&!isObj[previous])   ||
           (!isObj[current]&&isObj[previous])){
          vertexSet.push_back(x);
          vertexSet.push_back(y);
          vertexSet.push_back(x+1);
          vertexSet.push_back(y);
        }
      }
    }
    for(int y=ymin; y<=ymax; y++){
      // now for each row...
      for(int x=xmin+1;x<=xmax;x++){
        int current  = (y-ymin)*xsize + x-xmin;
        int previous = (y-ymin)*xsize + x-xmin - 1;
        if((isObj[current]&&!isObj[previous])   ||
           (!isObj[current]&&isObj[previous])){
          vertexSet.push_back(x);
          vertexSet.push_back(y);
          vertexSet.push_back(x);
          vertexSet.push_back(y+1);
        }
      }
    }

    return vertexSet;
  
  }
  //--------------------------------------------------------------------

  std::ostream& operator<< ( std::ostream& theStream, Detection& obj)
  {
    /**
     *  A convenient way of printing the coordinate values for each
     *  pixel in the Detection.  
     *
     *  NOTE THAT THERE IS CURRENTLY NO FLUX INFORMATION BEING PRINTED!
     *
     *  Use as front end to the Object3D::operator<< function.
     */  

    theStream << obj.pixelArray << "---\n";
    return theStream;
  }
  //--------------------------------------------------------------------

}