VTK/Examples/Cxx/Meshes/ColoredElevationMap

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VTK Examples Baseline Meshes TestColoredElevationMap.png

ColoredElevationMap.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
 
#include <vtkActor.h>
#include <vtkDelaunay2D.h>
#include <vtkLookupTable.h>
#include <vtkMath.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkVertexGlyphFilter.h>
#include <vtkXMLPolyDataWriter.h>
 
// For compatibility with new VTK generic data arrays
#ifdef vtkGenericDataArray_h
#define InsertNextTupleValue InsertNextTypedTuple
#endif
 
int main(int, char *[])
{
  // Create a grid of points (height/terrian map)
  vtkSmartPointer<vtkPoints> points = 
    vtkSmartPointer<vtkPoints>::New();
 
  unsigned int GridSize = 20;
  double xx, yy, zz;
  for(unsigned int x = 0; x < GridSize; x++)
    {
    for(unsigned int y = 0; y < GridSize; y++)
      {
      xx = x + vtkMath::Random(-.2, .2);
      yy = y + vtkMath::Random(-.2, .2);
      zz = vtkMath::Random(-.5, .5);
      points->InsertNextPoint(xx, yy, zz);
      }
    }
 
  // Add the grid points to a polydata object
  vtkSmartPointer<vtkPolyData> inputPolyData = 
    vtkSmartPointer<vtkPolyData>::New();
  inputPolyData->SetPoints(points);
 
  // Triangulate the grid points
  vtkSmartPointer<vtkDelaunay2D> delaunay = 
    vtkSmartPointer<vtkDelaunay2D>::New();
#if VTK_MAJOR_VERSION <= 5
  delaunay->SetInput(inputPolyData);
#else
  delaunay->SetInputData(inputPolyData);
#endif
  delaunay->Update();
  vtkPolyData* outputPolyData = delaunay->GetOutput();
 
  double bounds[6];
  outputPolyData->GetBounds(bounds);
 
  // Find min and max z
  double minz = bounds[4];
  double maxz = bounds[5];
 
  std::cout << "minz: " << minz << std::endl;
  std::cout << "maxz: " << maxz << std::endl;
 
  // Create the color map
  vtkSmartPointer<vtkLookupTable> colorLookupTable = 
    vtkSmartPointer<vtkLookupTable>::New();
  colorLookupTable->SetTableRange(minz, maxz);
  colorLookupTable->Build();
 
  // Generate the colors for each point based on the color map
  vtkSmartPointer<vtkUnsignedCharArray> colors = 
    vtkSmartPointer<vtkUnsignedCharArray>::New();
  colors->SetNumberOfComponents(3);
  colors->SetName("Colors");
 
  std::cout << "There are " << outputPolyData->GetNumberOfPoints()
            << " points." << std::endl;
 
  for(int i = 0; i < outputPolyData->GetNumberOfPoints(); i++)
    {
    double p[3];
    outputPolyData->GetPoint(i,p);
 
    double dcolor[3];
    colorLookupTable->GetColor(p[2], dcolor);
    std::cout << "dcolor: "
              << dcolor[0] << " "
              << dcolor[1] << " "
              << dcolor[2] << std::endl;
    unsigned char color[3];
    for(unsigned int j = 0; j < 3; j++)
      {
      color[j] = static_cast<unsigned char>(255.0 * dcolor[j]);
      }
    std::cout << "color: "
              << (int)color[0] << " "
              << (int)color[1] << " "
              << (int)color[2] << std::endl;
 
    colors->InsertNextTupleValue(color);
    }
 
  outputPolyData->GetPointData()->SetScalars(colors);
 
  // Create a mapper and actor
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
#if VTK_MAJOR_VERSION <= 5
  mapper->SetInputConnection(outputPolyData->GetProducerPort());
#else
  mapper->SetInputData(outputPolyData);
#endif
 
  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);
 
  // Create a renderer, render window, and interactor
  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);
 
  // Add the actor to the scene
  renderer->AddActor(actor);
  renderer->SetBackground(.1, .2, .3);
 
  // Render and interact
  renderWindow->Render();
  renderWindowInteractor->Start();
 
  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
 
PROJECT(ColoredElevationMap)
 
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})
 
add_executable(ColoredElevationMap MACOSX_BUNDLE ColoredElevationMap.cxx)
 
if(VTK_LIBRARIES)
  target_link_libraries(ColoredElevationMap ${VTK_LIBRARIES})
else()
  target_link_libraries(ColoredElevationMap vtkHybrid vtkWidgets)
endif()

Download and Build ColoredElevationMap

Click here to download ColoredElevationMap. and its CMakeLists.txt file.

Once the tarball ColoredElevationMap.tar has been downloaded and extracted,

cd ColoredElevationMap/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:

./ColoredElevationMap

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