DGtal  1.0.0
geometry/volumes/distance/distancetransform2D.cpp

Example of distance transformation in dimension 2.

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/TickedColorMap.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
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)
(*it)=128;
//We generate 16 seeds with 0 values.
randomSeeds(image,16,0);
//Input shape output
Board2D board;
Display2DFactory::drawImage<Gray>(board, image, (unsigned int)0, (unsigned int)129);
board.saveSVG("inputShape.svg");
//Point Predicate from random seed image
PointPredicate predicate(image,0);
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
trace.warning() << dtL2 << " maxValue= "<<maxv2<< endl;
board.clear();
Display2DFactory::drawImage<HueTwice>(board, dtL2, 0.0, maxv2 + 1);
board.saveSVG ( "example-DT-L2.svg" );
trace.warning() << dtL1 << " maxValue= "<<maxv1<< endl;
board.clear();
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
board.clear();