DGtal 1.3.0
No Matches

In many circumstances, it is better to use the presented graph structure of digital surfaces. For instance it may be used to find the surface just by searching it by adjacencies. This process is called tracking. This is done for you by static method Surfaces::trackBoundary.

See also
Constructing digital surfaces by tracking

On the lobser.vol volume, volTrackBoundary.cpp extracts 148364 surfels in 351ms.

* # Commands
* $ ./examples/topology/volTrackBoundary ../examples/samples/lobster.vol 50 255
Digital surface that is the boundary of a (6,18)-connected component in image lobst* er.vol, extracted by tracking from an initial surfel in 351ms.
#include <iostream>
#include <queue>
#include "DGtal/base/Common.h"
#include "DGtal/io/viewers/Viewer3D.h"
#include "DGtal/io/readers/VolReader.h"
#include "DGtal/io/DrawWithDisplay3DModifier.h"
#include "DGtal/io/Color.h"
#include "DGtal/images/ImageSelector.h"
#include "DGtal/images/imagesSetsUtils/SetFromImage.h"
#include "DGtal/shapes/Shapes.h"
#include "DGtal/helpers/StdDefs.h"
#include "DGtal/topology/helpers/Surfaces.h"
using namespace std;
using namespace DGtal;
using namespace Z3i;
void usage( int /*argc*/, char** argv )
std::cerr << "Usage: " << argv[ 0 ] << " <fileName.vol> <minT> <maxT>" << std::endl;
std::cerr << "\t - displays the boundary of the shape stored in vol file <fileName.vol>." << std::endl;
std::cerr << "\t - voxel v belongs to the shape iff its value I(v) follows minT <= I(v) <= maxT." << std::endl;
int main( int argc, char** argv )
if ( argc < 4 )
usage( argc, argv );
return 1;
std::string inputFilename = argv[ 1 ];
unsigned int minThreshold = atoi( argv[ 2 ] );
unsigned int maxThreshold = atoi( argv[ 3 ] );
trace.beginBlock( "Reading vol file into an image." );
typedef ImageSelector < Domain, int>::Type Image;
Image image = VolReader<Image>::importVol(inputFilename);
DigitalSet set3d (image.domain());
minThreshold, maxThreshold);
trace.beginBlock( "Construct the Khalimsky space from the image domain." );
KSpace ks;
bool space_ok = ks.init( image.domain().lowerBound(),
image.domain().upperBound(), true );
if (!space_ok)
trace.error() << "Error in the Khamisky space construction."<<std::endl;
return 2;
typedef SurfelAdjacency<KSpace::dimension> MySurfelAdjacency;
MySurfelAdjacency surfAdj( true ); // interior in all directions.
trace.beginBlock( "Extracting boundary by tracking from an initial bel." );
KSpace::SCellSet boundary;
SCell bel = Surfaces<KSpace>::findABel( ks, set3d, 100000 );
set3d, bel );
trace.beginBlock( "Displaying surface in Viewer3D." );
QApplication application(argc,argv);
Viewer3D<> viewer( ks );
viewer << SetMode3D( bel.className(), "Basic" );
viewer << CustomColors3D(Color(250, 0, 0 ), Color( 128, 128, 128 ) );
unsigned long nbSurfels = 0;
for ( KSpace::SCellSet::const_iterator it = boundary.begin(),
it_end = boundary.end(); it != it_end; ++it, ++nbSurfels )
viewer << *it;
viewer << Viewer3D<>::updateDisplay;
trace.info() << "nb surfels = " << nbSurfels << std::endl;
return application.exec();
Structure representing an RGB triple with alpha component.
Definition: Color.h:68
Aim: A utility class for constructing surfaces (i.e. set of (n-1)-cells).
Definition: Surfaces.h:79
Aim: Represent adjacencies between surfel elements, telling if it follows an interior to exterior ord...
void beginBlock(const std::string &keyword="")
std::ostream & error()
std::ostream & info()
double endBlock()
Z3i::SCell SCell
DGtal is the top-level namespace which contains all DGtal functions and types.
Trace trace
Definition: Common.h:154
STL namespace.
Aim: Define utilities to convert a digital set into an image.
Definition: SetFromImage.h:64
Modifier class in a Display3D stream. Useful to choose your own mode for a given class....
Aim: implements methods to read a "Vol" file format.
Definition: VolReader.h:90
int main()
Definition: testBits.cpp:56
ImageContainerBySTLVector< Domain, Value > Image
Z2i::DigitalSet DigitalSet