MetadataExample.cxxΒΆ
Example source code (MetadataExample.cxx):
// This example illustrates the access to metadata image information
// with OTB. By metadata, we mean data which is typically stored with
// remote sensing images, like geographical coordinates of pixels,
// pixel spacing or resolution, etc. Of course, the availability of
// these data depends on the image format used and on the fact that
// the image producer must fill the available metadata fields. The
// image formats which typically support metadata are for example
// CEOS and GeoTiff.
//
// The metadata support is embedded in OTB's IO functionalities and
// is accessible through the \doxygen{otb}{Image} and
// \doxygen{otb}{VectorImage} classes. You should avoid using the
// \doxygen{itk}{Image} class if you want to have metadata support.
#include "itkMacro.h"
#include <iostream>
#include <fstream>
#include <string>
#include "otbImage.h"
#include "otbImageFileReader.h"
int main(int itkNotUsed(argc), char* argv[])
{
// Verify the number of parameters in the command line
const char* inputFilename = argv[1];
const char* outputAsciiFilename = argv[2];
// This simple example will consist on reading an image from a file
// and writing the metadata to an output ASCII file. As usual we
// start by defining the types needed for the image to be read.
using InputPixelType = unsigned char;
const unsigned int Dimension = 2;
using InputImageType = otb::Image<InputPixelType, Dimension>;
using ReaderType = otb::ImageFileReader<InputImageType>;
// We can now instantiate the reader and get a pointer to the input image.
ReaderType::Pointer reader = ReaderType::New();
InputImageType::Pointer image = InputImageType::New();
reader->SetFileName(inputFilename);
reader->Update();
image = reader->GetOutput();
// Once the image has been read, we can access the metadata
// information. We will copy this information to an ASCII file, so we
// create an output file stream for this purpose.
std::ofstream file;
file.open(outputAsciiFilename);
// We can now call the different available methods for accessing the
// metadata. Useful methods are :
// \begin{itemize}
// \item \code{GetSpacing}: the sampling step;
// \item \code{GetOrigin}: the coordinates of the origin of the image;
// \item \code{GetProjectionRef}: the image projection reference;
// \item \code{GetGCPProjection}: the projection for the eventual
// ground control points;
// \item \code{GetGCPCount}: the number of GCPs available;
// \end{itemize}
file << "Spacing " << image->GetSignedSpacing() << std::endl;
file << "Origin " << image->GetOrigin() << std::endl;
file << "Projection REF " << image->GetProjectionRef() << std::endl;
file << "GCP Projection " << image->GetGCPProjection() << std::endl;
unsigned int GCPCount = image->GetGCPCount();
file << "GCP Count " << image->GetGCPCount() << std::endl;
// One can also get the GCPs by number, as well as their coordinates
// in image and geographical space.
for (unsigned int GCPnum = 0; GCPnum < GCPCount; GCPnum++)
{
file << "GCP[" << GCPnum << "] Id " << image->GetGCPId(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] Info " << image->GetGCPInfo(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] Row " << image->GetGCPRow(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] Col " << image->GetGCPCol(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] X " << image->GetGCPX(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] Y " << image->GetGCPY(GCPnum) << std::endl;
file << "GCP[" << GCPnum << "] Z " << image->GetGCPZ(GCPnum) << std::endl;
file << "----------------" << std::endl;
}
// If a geographical transformation is available, it can be recovered
// as follows.
InputImageType::VectorType tab = image->GetGeoTransform();
file << "Geo Transform " << std::endl;
for (unsigned int i = 0; i < tab.size(); ++i)
{
file << " " << i << " -> " << tab[i] << std::endl;
}
tab.clear();
tab = image->GetUpperLeftCorner();
file << "Corners " << std::endl;
for (unsigned int i = 0; i < tab.size(); ++i)
{
file << " UL[" << i << "] -> " << tab[i] << std::endl;
}
tab.clear();
tab = image->GetUpperRightCorner();
for (unsigned int i = 0; i < tab.size(); ++i)
{
file << " UR[" << i << "] -> " << tab[i] << std::endl;
}
tab.clear();
tab = image->GetLowerLeftCorner();
for (unsigned int i = 0; i < tab.size(); ++i)
{
file << " LL[" << i << "] -> " << tab[i] << std::endl;
}
tab.clear();
tab = image->GetLowerRightCorner();
for (unsigned int i = 0; i < tab.size(); ++i)
{
file << " LR[" << i << "] -> " << tab[i] << std::endl;
}
tab.clear();
file.close();
return EXIT_SUCCESS;
}