voronoi.cxx

Generate a Voronoi diagram, using distanceTransform() and seededRegionGrowing()
Usage: example_voronoi, generates: distances.gif (Euclidean distance transform) and voronoi.gif (Voronoi diagram)

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/*               Copyright 1998-2002 by Ullrich Koethe                  */
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#include <iostream>
#include <vigra/multi_array.hxx>
#include <vigra/random.hxx>
#include <vigra/distancetransform.hxx>
#include <vigra/labelimage.hxx>
#include <vigra/seededregiongrowing.hxx>
#include <vigra/impex.hxx>

using namespace vigra; 

int main(int argc, char ** argv)
{
    try
    {
        int number_of_points = 25;
        int size = 512;
        
        // create input image
        MultiArray<2, float> in(size, size);
        
        MersenneTwister random;
        for(int i=1; i<=number_of_points; ++i)
        {
            // mark a number of points 
            int x = random.uniformInt(size);
            int y = random.uniformInt(size);
            
            // label each point with a unique number
            in(x,y) = i;
        }
        
        // create output image and paint it white
        MultiArray<2, int> out(size, size);
        out = 255;
        
        // in the output image, paint the points black which were 
        // marked in the input image
        initImageIf(out, in, 0);
        
        // create image to hold the distance transform
        MultiArray<2, float> distances(size, size);
        
        // calculate Euclidean distance transform
        // all pixels with value 0 are considered background
        distanceTransform(in, distances, 0, 2);
        
        exportImage(distances, ImageExportInfo("distances.gif"));
        std::cout << "Wrote distance transform (distances.gif)" << std::endl;
        
        // initialize statistics functor for region growing
        ArrayOfRegionStatistics<SeedRgDirectValueFunctor<float> > statistics(number_of_points);

        // perform region growing, starting at the points marked in the input
        // image; as the feature (first source) image contains the distances,
        // the will calculate the voronoi regions of these points
        seededRegionGrowing(distances, in, in, statistics);
        
        // in the output image, mark the borders of the voronoi regions black 
        regionImageToEdgeImage(in, out, 0);

        exportImage(out, ImageExportInfo("voronoi.gif"));
        std::cout << "Wrote voronoi diagram (voronoi.gif)" << std::endl;
    }
    catch (std::exception & e)
    {
        std::cout << e.what() << std::endl;
        return 1;
    }
    
    return 0;
}