#ifndef INITIAL_OPENGL

#define INITIAL_OPENGL

#include <vtkAutoInit.h>

VTK_MODULE_INIT(vtkRenderingOpenGL)

VTK_MODULE_INIT(vtkInteractionStyle)

#endif

#include <iostream>

using namespace std;

#include <vtkVersion.h>

#include <vtkPolyData.h>

#include <vtkProperty.h>

#include <vtkMath.h>

#include <vtkSmartPointer.h>

#include <vtkPolyDataMapper.h>

#include <vtkActor.h>

#include <vtkRenderWindow.h>

#include <vtkRenderer.h>

#include <vtkRenderWindowInteractor.h>

#include <vtkImageData.h>

#include <vtkGreedyTerrainDecimation.h>

#include <vtkInteractorStyleTrackballCamera.h>

#include <vtkInteractionWidgetsModule.h>

void myShow(vtkGreedyTerrainDecimation* anInput)

{

    vtkSmartPointer<vtkPolyDataMapper> aMapper=vtkSmartPointer<vtkPolyDataMapper>::New();

    aMapper->SetInputConnection(anInput->GetOutputPort());

    aMapper->ScalarVisibilityOn();

    vtkSmartPointer<vtkActor> anActor=vtkSmartPointer<vtkActor>::New();

    anActor->SetMapper(aMapper);

    anActor->GetProperty()->SetInterpolationToFlat();

    anActor->GetProperty()->EdgeVisibilityOn();

    anActor->GetProperty()->SetEdgeColor(1,0,0);

    vtkSmartPointer<vtkRenderer> ren1=vtkSmartPointer<vtkRenderer>::New();

    vtkSmartPointer<vtkRenderWindow> renWin=vtkSmartPointer<vtkRenderWindow>::New();

    ren1->AddActor(anActor);

    ren1->ResetCamera();

    ren1->SetBackground(1,1,1);

    renWin->AddRenderer(ren1);

    renWin->SetSize(512,512);

    vtkSmartPointer<vtkRenderWindowInteractor> iren=vtkSmartPointer<vtkRenderWindowInteractor>::New();

    vtkSmartPointer<vtkInteractorStyleTrackballCamera> style=vtkSmartPointer<vtkInteractorStyleTrackballCamera>::New();

    iren->SetRenderWindow(renWin);

    iren->SetInteractorStyle(style);

    iren->Start();

}

int main()

{

    vtkSmartPointer<vtkImageData> image=vtkSmartPointer<vtkImageData>::New();

    image->SetDimensions(20,20,1);//头两个参数分别是沿x、y方向的取样点数，第三个参数是z方向的取样点数

    image->AllocateScalars(VTK_UNSIGNED_CHAR,1);

    int dims[3];

    image->GetDimensions(dims);

    for(double i=0;i<dims[0];i++)

    {

        for(double j=0;j<dims[1];j++)

        {

            unsigned char* pixel=static_cast<unsigned char*>(image->GetScalarPointer(i,j,0));

            pixel[0]=vtkMath::Round(vtkMath::Random(0,5));//在（i,j）位置上的“高”

        }

    }

    vtkSmartPointer<vtkGreedyTerrainDecimation>decimation=vtkSmartPointer<vtkGreedyTerrainDecimation>::New();

    decimation->SetInputData(image);

    decimation->Update();

    //可视化

    myShow(decimation);

    return 0;

}

VTK初学一，a Mesh from vtkImageData