GeoGraticle

Description¶

vtkGeoGraticle generates polydata to illustrate the distortions introduced by a map projection. The level parameter specifies the number of lines to be drawn. Poles are treated differently than other regions; hence the use of a Level parameter instead of a NumberOfLines parameter. The latitude and longitude are specified as half-open intervals with units of degrees. By default the latitude bounds are [-90,90[ and the longitude bounds are [0,180[.

Note

The vtkGeovisCore classes as well as the module vtkViewsGeovis have been deprecated for VTK 8.2 and will be removed in a future version. See VTK Merge Request 4395

Code¶

GeoGraticle.cxx

#include <vtkSmartPointer.h>
#include <vtkGeoGraticule.h>

#include <vtkActor.h>
#include <vtkGeoProjection.h>
#include <vtkGeoTransform.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkTransformFilter.h>
#include <vtkXMLPolyDataReader.h>

#include <vtkNamedColors.h>

int main( int argc, char* argv[] )
{
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  int latLevel = 2;
  int lngLevel = 2;
  const char* pname = "rouss";

  vtkSmartPointer<vtkGeoGraticule> geoGraticle =
    vtkSmartPointer<vtkGeoGraticule>::New();
  vtkSmartPointer<vtkGeoTransform> transformProjection =
    vtkSmartPointer<vtkGeoTransform>::New();
  vtkSmartPointer<vtkGeoProjection> destinationProjection =
    vtkSmartPointer<vtkGeoProjection>::New();
  vtkSmartPointer<vtkGeoProjection> sourceProjection =
    vtkSmartPointer<vtkGeoProjection>::New();
  vtkSmartPointer<vtkTransformFilter> transformGraticle =
    vtkSmartPointer<vtkTransformFilter>::New();
  vtkSmartPointer<vtkXMLPolyDataReader> reader =
    vtkSmartPointer<vtkXMLPolyDataReader>::New();
  vtkSmartPointer<vtkTransformFilter> transformReader =
    vtkSmartPointer<vtkTransformFilter>::New();
  vtkSmartPointer<vtkPolyDataMapper> graticleMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  vtkSmartPointer<vtkPolyDataMapper> readerMapper =
    vtkSmartPointer<vtkPolyDataMapper>::New();
  vtkSmartPointer<vtkActor> graticleActor =
    vtkSmartPointer<vtkActor>::New();
  vtkSmartPointer<vtkActor> readerActor =
    vtkSmartPointer<vtkActor>::New();

  geoGraticle->SetGeometryType( vtkGeoGraticule::POLYLINES );
  geoGraticle->SetLatitudeLevel( latLevel );
  geoGraticle->SetLongitudeLevel( lngLevel );
  geoGraticle->SetLongitudeBounds( -180, 180 );
  geoGraticle->SetLatitudeBounds( -90, 90 );

  // destinationProjection defaults to latlong.
  destinationProjection->SetName( pname );
  destinationProjection->SetCentralMeridian( 0. );
  transformProjection->SetSourceProjection( sourceProjection );
  transformProjection->SetDestinationProjection( destinationProjection );
  transformGraticle->SetInputConnection( geoGraticle->GetOutputPort() );
  transformGraticle->SetTransform( transformProjection );
  graticleMapper->SetInputConnection( transformGraticle->GetOutputPort() );
  graticleActor->SetMapper( graticleMapper );

  reader->SetFileName(argv[1]);
  transformReader->SetTransform( transformProjection );
  transformReader->SetInputConnection( reader->GetOutputPort() );
  readerMapper->SetInputConnection( transformReader->GetOutputPort() );
  readerActor->SetMapper( readerMapper );

  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindowInteractor> interactor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindow->SetInteractor( interactor );
  renderWindow->AddRenderer( renderer );
  renderWindow->SetSize(640, 480);
  renderer->SetBackground(colors->GetColor3d("BurlyWood").GetData());

  renderer->AddActor( readerActor );
  renderer->AddActor( graticleActor );

  renderWindow->Render();

  interactor->Initialize();
  interactor->Start();
  return EXIT_SUCCESS;
};

CMakeLists.txt¶

cmake_minimum_required(VERSION 2.8)

PROJECT(GeoGraticle)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(GeoGraticle MACOSX_BUNDLE GeoGraticle.cxx )

target_link_libraries(GeoGraticle ${VTK_LIBRARIES})

Download and Build GeoGraticle¶

Click here to download GeoGraticle and its CMakeLists.txt file. Once the tarball GeoGraticle.tar has been downloaded and extracted,

cd GeoGraticle/build

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./GeoGraticle

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.