VectorDataExtractROIExample.cxxΒΆ
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 focus 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 "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);
region.SetRegionProjection(imageReader->GetOutput()->GetProjectionRef());
region.SetImageMetadata(imageReader->GetOutput()->GetImageMetadata());
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;
}