LabelMapToVectorData.cxxΒΆ
Example usage:
./LabelMapToVectorData Input/labelImage_UnsignedChar.tif Output/LabelMapToVectorData.shp
Example source code (LabelMapToVectorData.cxx):
// \index{otb::LabelMapToVectorDataFilter}
//
//
// This class vectorizes a LabelObject to a VectorData.
//
// The \doxygen{otb}{LabelMapToVectorDataFilter} converts an \doxygen{itk}{LabelMap} to an
// \doxygen{otb}{VectorData} where all the pixels get the attribute
// value of the label object they belong to.
// It uses the class \doxygen{otb}{LabelObjectToPolygonFunctor} which
// follows a finite state machine described in \cite{Francis2000}.
//
// Only polygon conversion is available yet.
#include "otbImageFileReader.h"
#include "otbVectorDataFileWriter.h"
#include "otbVectorData.h"
#include "otbVectorDataProjectionFilter.h"
#include <fstream>
#include <iostream>
#include "otbImage.h"
// These are the main header files which need to be included:
#include "otbLabelMapToVectorDataFilter.h"
#include "otbAttributesMapLabelObject.h"
#include "itkLabelImageToLabelMapFilter.h"
int main(int argc, char* argv[])
{
/** Use the labelObjecttopolygon functor (not thread safe) only polygon conversion is available yet*/
if (argc != 3)
{
std::cerr << "Usage: " << argv[0];
std::cerr << " inputImageFile outputVectorfile(shp)" << std::endl;
return EXIT_FAILURE;
}
const char* infname = argv[1];
const char* outfname = argv[2];
// The image types are defined using pixel types and
// dimension. The input image is defined as an \doxygen{itk}{Image},
// the output is a \doxygen{otb}{VectorData}.
const unsigned int Dimension = 2;
using LabelType = unsigned short;
using LabeledImageType = otb::Image<LabelType, Dimension>;
using VectorDataType = otb::VectorData<double, 2>;
// We instantiate reader and writer types
using LabeledReaderType = otb::ImageFileReader<LabeledImageType>;
using WriterType = otb::VectorDataFileWriter<VectorDataType>;
// Label map typedef
// The Attribute Label Map is
// instantiated using the image pixel types as template parameters.
// The LabelObjectToPolygonFunctor is instantiated with LabelObjectType and PolygonType.
using LabelObjectType = otb::AttributesMapLabelObject<LabelType, Dimension, double>;
using LabelMapType = itk::LabelMap<LabelObjectType>;
using LabelMapFilterType = itk::LabelImageToLabelMapFilter<LabeledImageType, LabelMapType>;
LabeledReaderType::Pointer lreader = LabeledReaderType::New();
WriterType::Pointer writer = WriterType::New();
// Now the reader and writer are instantiated and
// the input image is set and a name is given to the output image.
lreader->SetFileName(infname);
writer->SetFileName(outfname);
// Then, the input image is converted to a map of label objects.
// Here each white region connected regions are converted. So the background is define all zero pixels.
LabelMapFilterType::Pointer labelMapFilter = LabelMapFilterType::New();
labelMapFilter->SetInput(lreader->GetOutput());
labelMapFilter->SetBackgroundValue(itk::NumericTraits<LabelType>::min());
labelMapFilter->Update();
// Then, the \doxygen{otb}{LabelMapToVectorDataFilter} is instantiated. This is
// the main filter which performs the vectorization.
using LabelMapToVectorDataFilterType = otb::LabelMapToVectorDataFilter<LabelMapType, VectorDataType>;
LabelMapToVectorDataFilterType::Pointer MyFilter = LabelMapToVectorDataFilterType::New();
MyFilter->SetInput(labelMapFilter->GetOutput());
MyFilter->Update();
MyFilter->GetOutput()->SetProjectionRef(lreader->GetOutput()->GetProjectionRef());
// The output can be passed to a writer.
writer->SetInput(MyFilter->GetOutput());
// The invocation of the \code{Update()} method on the writer triggers the
// execution of the pipeline. As usual, it is recommended to place update calls in a
// \code{try/catch} block in case errors occur and exceptions are thrown.
try
{
writer->Update();
return EXIT_SUCCESS;
}
catch (itk::ExceptionObject& excep)
{
std::cerr << "Exception caught !" << std::endl;
std::cerr << excep << std::endl;
}
catch (...)
{
std::cout << "Unknown exception !" << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}