geometry/curves/estimation/exampleCurvature.cpp

Example of curvature estimation based on Digital Circular Arc (DCA) estimator.

Curvature estimated using DCA estimator on a flower shape.

#include <iostream>
#include "DGtal/base/Common.h"

#include "DGtal/kernel/SpaceND.h"
#include "DGtal/kernel/domains/HyperRectDomain.h"
#include "DGtal/topology/KhalimskySpaceND.h"
#include "DGtal/topology/SurfelAdjacency.h"
#include "DGtal/topology/SurfelNeighborhood.h"

#include "DGtal/shapes/Shapes.h"
#include "DGtal/shapes/ShapeFactory.h"
#include "DGtal/shapes/GaussDigitizer.h"
#include "DGtal/geometry/curves/GridCurve.h"

#include "DGtal/geometry/curves/estimation/MostCenteredMaximalSegmentEstimator.h"
#include "DGtal/geometry/curves/StabbingCircleComputer.h"


using namespace std;
using namespace DGtal;


template <typename Shape, typename RealPoint>
bool
estimatorOnShapeDigitization( const string& name,
                              Shape & aShape,
                              const RealPoint& low, const RealPoint& up,
                              double h )
{
  using namespace Z2i;

  trace.beginBlock ( ( "Curvature estimation on digitization of "
                       + name ). c_str() );

  // Creates a digitizer on the window (low, up).
  GaussDigitizer<Space,Shape> dig;
  dig.attach( aShape ); // attaches the shape.
  dig.init( low, up, h );

  // The domain size is given by the digitizer
  // according to the window and the step.
  Domain domain = dig.getDomain();

  // Create cellular space
  KSpace K;
  bool ok = K.init( dig.getLowerBound(), dig.getUpperBound(), true );
  if ( ! ok )
    {
      std::cerr << "[estimatorOnShapeDigitization]"
                << " error in creating KSpace." << std::endl;
    }
  else
    try {
      // Extracts shape boundary
      SurfelAdjacency<KSpace::dimension> SAdj( true );
      SCell bel = Surfaces<KSpace>::findABel( K, dig, 10000 );
      // Getting the consecutive surfels of the 2D boundary
      std::vector<Point> points;
      Surfaces<KSpace>::track2DBoundaryPoints( points, K, SAdj, dig, bel );
      // Create GridCurve
      GridCurve<KSpace> gridcurve( K );
      gridcurve.initFromVector( points );
      // Create range of incident points
      typedef GridCurve<KSpace>::IncidentPointsRange Range;
      typedef Range::ConstIterator ClassicIterator;
      typedef Range::ConstCirculator CircularIterator;
      Range r = gridcurve.getIncidentPointsRange();//building range
      // Estimation
      std::vector<double> estimations;
      if (gridcurve.isOpen())
        {
          typedef StabbingCircleComputer<ClassicIterator> SegmentComputer;
          typedef CurvatureFromDCAEstimator<SegmentComputer> SCEstimator;
          typedef MostCenteredMaximalSegmentEstimator<SegmentComputer,SCEstimator> CurvatureEstimator;
          SegmentComputer sc;
          SCEstimator sce;
          CurvatureEstimator estimator(sc, sce);

          std::cout << "# open grid curve" << endl;
          
          estimator.init( h, r.begin(), r.end() );
          
          estimator.eval( r.begin(), r.end(), std::back_inserter(estimations) );
        }
      else
        {
          typedef StabbingCircleComputer<CircularIterator> SegmentComputer;
          typedef CurvatureFromDCAEstimator<SegmentComputer> SCEstimator;
          typedef MostCenteredMaximalSegmentEstimator<SegmentComputer,SCEstimator> CurvatureEstimator;
          SegmentComputer sc;
          SCEstimator sce;
          CurvatureEstimator estimator(sc, sce);
          std::cout << "# closed grid curve" << endl;
          estimator.init( h, r.c(), r.c() );
          estimator.eval( r.c(), r.c(), std::back_inserter(estimations) );
        }
      // Print (standard output)
      std::cout << "# idx kappa" << endl;
      unsigned int i = 0;
      for ( ClassicIterator it = r.begin(), ite = r.end();
           it != ite; ++it, ++i )
        {
          std::cout << i << " " << estimations.at(i) << std::endl;
        }
    }
  catch ( InputException e )
    {
      std::cerr << "[estimatorOnShapeDigitization]"
        << " error in finding a bel." << std::endl;
      ok = false;
    }
  trace.emphase() << ( ok ? "Passed." : "Error." ) << endl;
  trace.endBlock();
  return ok;
}

int main( )
{
  trace.beginBlock ( "Example exampleCurvature" );
  trace.info()  << " Curvature estimation using shape to digitize: flower" << std::endl
                << " with Grid step: 0.01" << std::endl;

  // grid step
  double h = 0.01;
  // shape
  string shapeName = "flower";


  // parse shape
  bool res = true;
  typedef Z2i::Space Space;
  typedef Space::RealPoint RealPoint;
  if (shapeName == "flower")
    {
      Flower2D<Space> flower( 0.5, 0.5, 5.0, 3.0, 5, 0.3 );
      res = estimatorOnShapeDigitization("flower", flower,
                                         RealPoint::diagonal(-10),
                                         RealPoint::diagonal(10),
                                         h);
    }
  else if (shapeName == "ellipse")
    {
      Ellipse2D<Space> ellipse( 0.5, 0.5, 5.0, 3.0, 0.3 );
      res = estimatorOnShapeDigitization("ellipse", ellipse,
                                         RealPoint::diagonal(-10),
                                         RealPoint::diagonal(10),
                                         h);
    }
  else if (shapeName == "ball")
    {
      Ball2D<Space> ball( 0.5, 0.5, 5.0 );
      res = estimatorOnShapeDigitization("ball", ball,
                                         RealPoint::diagonal(-10),
                                         RealPoint::diagonal(10),
                                         h);
    }


  trace.endBlock();

  return res;
}
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