VectorDataExtractROIExample.cxx

Example source code (VectorDataExtractROIExample.cxx):

// There is some vector data sets widely available on the internet. These data
// sets can be huge, covering an entire country, with hundreds of thousands
// objects.
//
// Most of the time, you won't be interested in the whole area and would like
// to focuss only on the area corresponding to your satellite image.
//
// The \doxygen{otb}{VectorDataExtractROI} is able to extract the area corresponding
// to your satellite image, even if the image is still in sensor geometry (provided
// the sensor model is supported by OTB). Let's see how we can do that.
//
// This example demonstrates the use of the
// \doxygen{otb}{VectorDataExtractROI}.

#include "otbVectorData.h"
#include "otbVectorDataExtractROI.h"

#include "otbVectorDataFileReader.h"
#include "otbVectorDataFileWriter.h"
#include "otbImageMetadataInterfaceFactory.h"

#include "otbImage.h"
#include "otbImageFileReader.h"

int main(int argc, char* argv[])
{
  if (argc < 4)
  {
    std::cout << argv[0] << " <input vector filename> <input image name> <output vector filename>  " << std::endl;

    return EXIT_FAILURE;
  }

  const char* inVectorName  = argv[1];
  const char* inImageName   = argv[2];
  const char* outVectorName = argv[3];

  using Type           = double;
  using VectorDataType = otb::VectorData<>;

  using VectorDataFileReaderType = otb::VectorDataFileReader<VectorDataType>;
  using VectorDataWriterType     = otb::VectorDataFileWriter<VectorDataType>;

  using TypedRegion = otb::RemoteSensingRegion<Type>;

  using ImageType                      = otb::Image<unsigned char, 2>;
  using ImageReaderType                = otb::ImageFileReader<ImageType>;
  ImageReaderType::Pointer imageReader = ImageReaderType::New();
  imageReader->SetFileName(inImageName);
  imageReader->UpdateOutputInformation();

  // After the usual declaration (you can check the source file for the details),
  // we can declare the \doxygen{otb}{VectorDataExtractROI}:

  using FilterType           = otb::VectorDataExtractROI<VectorDataType>;
  FilterType::Pointer filter = FilterType::New();

  // Then, we need to specify the region to extract. This region is a bit special as
  // it contains also information related to its reference system (cartographic projection
  // or sensor model projection). We retrieve all these information from the image
  // we gave as an input.

  TypedRegion            region;
  TypedRegion::SizeType  size;
  TypedRegion::IndexType index;

  size[0]  = imageReader->GetOutput()->GetLargestPossibleRegion().GetSize()[0] * imageReader->GetOutput()->GetSignedSpacing()[0];
  size[1]  = imageReader->GetOutput()->GetLargestPossibleRegion().GetSize()[1] * imageReader->GetOutput()->GetSignedSpacing()[1];
  index[0] = imageReader->GetOutput()->GetOrigin()[0] - 0.5 * imageReader->GetOutput()->GetSignedSpacing()[0];
  index[1] = imageReader->GetOutput()->GetOrigin()[1] - 0.5 * imageReader->GetOutput()->GetSignedSpacing()[1];
  region.SetSize(size);
  region.SetOrigin(index);

  otb::ImageMetadataInterfaceBase::Pointer imageMetadataInterface =
      otb::ImageMetadataInterfaceFactory::CreateIMI(imageReader->GetOutput()->GetMetaDataDictionary());
  region.SetRegionProjection(imageMetadataInterface->GetProjectionRef());

  region.SetKeywordList(imageReader->GetOutput()->GetImageKeywordlist());

  filter->SetRegion(region);

  VectorDataFileReaderType::Pointer reader = VectorDataFileReaderType::New();
  VectorDataWriterType::Pointer     writer = VectorDataWriterType::New();
  reader->SetFileName(inVectorName);
  writer->SetFileName(outVectorName);

  // And finally, we can plug the filter in the pipeline:

  filter->SetInput(reader->GetOutput());
  writer->SetInput(filter->GetOutput());

  writer->Update();

  return EXIT_SUCCESS;
}