DGtal  1.4.beta

Example of distance transformation in dimension 2.

See also
nD Volumetric Analysis using Separable Processes
Distance transform with L2 norm.
#include <iostream>
#include <iomanip>
#include "DGtal/base/Common.h"
#include "DGtal/helpers/StdDefs.h"
#include "DGtal/io/colormaps/GrayscaleColorMap.h"
#include "DGtal/io/colormaps/HueShadeColorMap.h"
#include "DGtal/io/colormaps/TickedColorMap.h"
#include "DGtal/io/colormaps/GradientColorMap.h"
#include "DGtal/io/boards/Board2D.h"
#include "DGtal/images/ImageSelector.h"
#include "DGtal/images/SimpleThresholdForegroundPredicate.h"
#include "DGtal/geometry/volumes/distance/DistanceTransformation.h"
using namespace std;
using namespace DGtal;
template<typename Image>
void randomSeeds(Image &image, const unsigned int nb, const int value)
typename Image::Point p, low = image.domain().lowerBound();
typename Image::Vector ext;
ext = image.extent();
for (unsigned int k = 0 ; k < nb; k++)
for (unsigned int dim = 0; dim < Image::dimension; dim++)
p[dim] = rand() % (ext[dim]) + low[dim];
image.setValue(p, value);
int main()
trace.beginBlock ( "Example distancetransform2D" );
Z2i::Point a ( 0, 0 );
Z2i::Point b ( 127, 127);
//Input image with unsigned char values
typedef ImageSelector<Z2i::Domain, unsigned int>::Type Image;
Image image ( Z2i::Domain(a, b ));
//We fill the image with the 128 value
for ( Image::Iterator it = image.begin(), itend = image.end();it != itend; ++it)
//We generate 16 seeds with 0 values.
//Input shape output
typedef GrayscaleColorMap<Image::Value> Gray;
Board2D board;
board.setUnit ( LibBoard::Board::UCentimeter );
Display2DFactory::drawImage<Gray>(board, image, (unsigned int)0, (unsigned int)129);
//Point Predicate from random seed image
typedef functors::SimpleThresholdForegroundPredicate<Image> PointPredicate;
PointPredicate predicate(image,0);
typedef DistanceTransformation<Z2i::Space, PointPredicate, Z2i::L2Metric> DTL2;
typedef DistanceTransformation<Z2i::Space, PointPredicate, Z2i::L1Metric> DTL1;
DTL2 dtL2(image.domain(), predicate, Z2i::l2Metric);
DTL1 dtL1(image.domain(), predicate, Z2i::l1Metric);
DTL2::Value maxv2=0;
//We compute the maximum DT value on the L2 map
for ( DTL2::ConstRange::ConstIterator it = dtL2.constRange().begin(), itend = dtL2.constRange().end();it != itend; ++it)
if ( (*it) > maxv2) maxv2 = (*it);
DTL1::Value maxv1=0;
//We compute the maximum DT value on the L1 map
for ( DTL1::ConstRange::ConstIterator it = dtL1.constRange().begin(), itend = dtL1.constRange().end();it != itend; ++it)
if ( (*it) > maxv1) maxv1 = (*it);
//Colormap used for the SVG output
typedef HueShadeColorMap<DTL2::Value, 2> HueTwice;
trace.warning() << dtL2 << " maxValue= "<<maxv2<< endl;
Display2DFactory::drawImage<HueTwice>(board, dtL2, 0.0, maxv2 + 1);
board.saveSVG ( "example-DT-L2.svg" );
trace.warning() << dtL1 << " maxValue= "<<maxv1<< endl;
Display2DFactory::drawImage<HueTwice>(board, dtL1, 0.0, maxv1 + 1);
board.saveSVG ( "example-DT-L1.svg" );
//Explicit export with ticked colormap
//We compute the maximum DT value on the L2 map
TickedColorMap<double, GradientColorMap<double> > ticked(0.0,maxv2, Color::White);
ticked.addRegularTicks(5, 0.5);
ticked.colormap()->addColor( Color::Red );
ticked.colormap()->addColor( Color::Black );
for ( DTL2::Domain::ConstIterator it = dtL2.domain().begin(), itend = dtL2.domain().end();it != itend; ++it)
board<< CustomStyle((*it).className(),new CustomColors(ticked(dtL2(*it)),ticked(dtL2(*it))));
board << *it;
return 0;
// //
void beginBlock(const std::string &keyword="")
std::ostream & warning()
double endBlock()
DigitalPlane::Point Vector
MyDigitalSurface::ConstIterator ConstIterator
DGtal is the top-level namespace which contains all DGtal functions and types.
Trace trace
Definition: Common.h:153
int main(int argc, char **argv)
MyPointD Point
Definition: testClone2.cpp:383
void randomSeeds(Image &input, const unsigned int nb, const int value)
Image image(domain)
ImageContainerBySTLVector< Domain, Value > Image
HyperRectDomain< Space > Domain
unsigned int dim(const Vector &z)