VTK-数据集vtkUnstructuredGrid

前言：本博文主要介绍vtkUnstructuredGrid的特点、结构组成，vtkUnstructuredGrid的创建方法，及其vtkUnstructuredGrid相关的接口及示例。

目录

特点

创建方法

vtkUnstructuredGrid->vtkPolyData

vtkPolyData->vtkUnstructuredGrid

vtkUnstructuredGrid相关示例

---

特点

非结构化网格数据，是最常见的数据集类型，它的拓扑结构和几何结构都是非结构化的，所有单元类型都可以任意组合，所有单元的拓扑结构从零维延伸至三维。如上图f所示。在VTK中，任一类型的数据集都可用非结构化网格来表达，但其储存需要大量的空间，计算时需要消耗大量的资源，除非迫不得已，一般较少使用此种类型的数据集。主要用于有限元分析，计算几何和图形表示等领域。

创建方法

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellType.h>
#include <vtkDataSetMapper.h>
#include <vtkNamedColors.h>
#include <vtkPoints.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkUnstructuredGrid.h>

int main( int, char *[] )
{
  int i;
  static double x[27][3]={
   
   {0,0,0}, {1,0,0}, {2,0,0}, {0,1,0}, {1,1,0}, {2,1,0},
                          {0,0,1}, {1,0,1}, {2,0,1}, {0,1,1}, {1,1,1}, {2,1,1},
                          {0,1,2}, {1,1,2}, {2,1,2}, {0,1,3}, {1,1,3}, {2,1,3},
                          {0,1,4}, {1,1,4}, {2,1,4}, {0,1,5}, {1,1,5}, {2,1,5},
                          {0,1,6}, {1,1,6}, {2,1,6}};
  static vtkIdType pts[12][8]={
   
   {0, 1, 4, 3, 6, 7, 10, 9},
                               {1, 2, 5, 4, 7, 8, 11, 10},
                               {6, 10, 9, 12, 0, 0, 0, 0},
                               {8, 11, 10, 14, 0, 0, 0, 0},
                               {16, 17, 14, 13, 12, 15, 0, 0},
                               {18, 15, 19, 16, 20, 17, 0, 0},
                               {22, 23, 20, 19, 0, 0, 0, 0},
                               {21, 22, 18, 0, 0, 0, 0, 0},
                               {22, 19, 18, 0, 0, 0, 0, 0},
                               {23, 26, 0, 0, 0, 0, 0, 0},
                               {21, 24, 0, 0, 0, 0, 0, 0},
                               {25, 0, 0, 0, 0, 0, 0, 0}};

  
  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

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

  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(renderer);
  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);

  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
  for (i=0; i<27; i++) points->InsertPoint(i,x[i]);
  
  vtkSmartPointer<vtkUnstructuredGrid> ugrid =
    vtkSmartPointer<vtkUnstructuredGrid>::New();
  ugrid->Allocate(100);
  ugrid->InsertNextCell(VTK_HEXAHEDRON, 8, pts[0]);
  ugrid->InsertNextCell(VTK_HEXAHEDRON, 8, pts[1]);
  ugrid->InsertNextCell(VTK_TETRA, 4, pts[2]);
  ugrid->InsertNextCell(VTK_TETRA, 4, pts[3]);
  ugrid->InsertNextCell(VTK_POLYGON, 6, pts[4]);
  ugrid->InsertNextCell(VTK_TRIANGLE_STRIP, 6, pts[5]);
  ugrid->InsertNextCell(VTK_QUAD, 4, pts[6]);
  ugrid->InsertNextCell(VTK_TRIANGLE, 3, pts[7]);
  ugrid->InsertNextCell(VTK_TRIANGLE, 3, pts[8]);
  ugrid->InsertNextCell(VTK_LINE, 2, pts[9]);
  ugrid->InsertNextCell(VTK_LINE, 2, pts[10]);
  ugrid->InsertNextCell(VTK_VERTEX, 1, pts[11]);

  ugrid->SetPoints(points);

  vtkSmartPointer<vtkDataSetMapper> ugridMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  ugridMapper->SetInputData(ugrid);

  vtkSmartPointer<vtkActor> ugridActor =
    vtkSmartPointer<vtkActor>::New();
  ugridActor->SetMapper(ugridMapper);
  ugridActor->GetProperty()->SetColor(colors->GetColor3d("Peacock").GetData());
  ugridActor->GetProperty()->EdgeVisibilityOn();

  renderer->AddActor(ugridActor);
  renderer->SetBackground(colors->GetColor3d("Beige").GetData());

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Elevation(60.0);
  renderer->GetActiveCamera()->Azimuth(30.0);
  renderer->GetActiveCamera()->Dolly(1.2);
  
  renWin->SetSize(640, 480);

  // interact with data
  renWin->Render();

  iren->Start();

  return EXIT_SUCCESS;
}

vtkUnstructuredGrid->vtkPolyData

vtkUnstructuredGrid* unSGrid = ...
vtkDataSetSurfaceFilter * filter = vtkDataSetSurfaceFilter::New();
filter->SetInputData(unSGrid);
filter->Update();
vtkPolyData* pd = filter->GetOutput();

vtkPolyData->vtkUnstructuredGrid

vtkUnstructuredGrid* zxCommonMethod::polyDataToUnstructuredGrid(vtkPolyData* pd)
{
	if (pd == nullptr) return nullptr;

	vtkPoints* inPts = pd->GetPoints();
	vtkIdType numPts = pd->GetNumberOfPoints();
	vtkCellArray* vertexs = pd->GetVerts();
	vtkCellArray* lines = pd->GetLines();
	vtkCellArray* polys = pd->GetPolys();
	vtkCellArray* strips = pd->GetStrips();
	vtkIdType numVertexs = pd->GetNumberOfVerts();
	vtkIdType numLines = pd->GetNumberOfLines();
	vtkIdType numPolys = pd->GetNumberOfPolys();
	vtkIdType numStrips = pd->GetNumberOfStrips();
	vtkIdType numCells = pd->GetNumberOfCells();
	if (numPts < 1 || (numVertexs + numLines + numPolys + numStrips) < 1) return nullptr;

	vtkUnstructuredGrid* uGrid = vtkUnstructuredGrid::New();
	uGrid->SetPoints(inPts);

	const vtkIdType* pts = nullptr;
	vtkIdType npts;
	for (vtkIdType id = 0; id < numCells; id++)
	{
		pd->GetCellPoints(id, npts, pts);
		uGrid->InsertNextCell(pd->GetCellType(id), npts, pts);
	}

	return uGrid;
}

vtkUnstructuredGrid相关示例

实例1：ClipUnstructuredGridWithPlane

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该实例使用vtkTableBasedClipDataSet对vtkUnstructuredGrid数据集进行Clip。与其它Clip相关的Filter不同，vtkTableBasedClipDataSet在未Clip的部分保留原来的Cells。

输入数据：treemesh.vtk

#include <vtkSmartPointer.h>
#include <vtkTableBasedClipDataSet.h>
#include <vtkUnstructuredGridReader.h>
#include <vtkUnstructuredGrid.h>
#include <vtkPlane.h>
#include <vtkTransform.h>

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellTypes.h>
#include <vtkDataSetMapper.h>
#include <vtkLookupTable.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <vtkNamedColors.h>

int main(int argc, char *argv[])
{
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " filename.vtk" << std::endl;
    return EXIT_FAILURE;
  }
  // Create the reader for the data.
  std::string filename = argv[1];
  std::cout << "Loading " << filename.c_str() << std::endl;
  auto reader =
    vtkSmartPointer<vtkUnstructuredGridReader>::New();
  reader->SetFileName(filename.c_str());
  reader->Update();

  double bounds[6];
  reader->GetOutput()->GetBounds(bounds);  
  double center[3];
  reader->GetOutput()->GetCenter(center);  

  auto colors =
    vtkSmartPointer<vtkNamedColors>::New();
  auto renderer = vtkSmartPointer<vtkRenderer>::New();
  renderer->SetBackground(colors->GetColor3d("Wheat").GetData());
  renderer->UseHiddenLineRemovalOn();

  auto renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderWindow->SetSize(640, 480);

  auto interactor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  double xnorm[3] = {-1.0, -1.0, 1.0};

  auto clipPlane = vtkSmartPointer<vtkPlane>::New();
  clipPlane->SetOrigin(reader->GetOutput()->GetCenter());
  clipPlane->SetNormal(xnorm);

  auto clipper =
    vtkSmartPointer<vtkTableBasedClipDataSet>::New();
  clipper->SetClipFunction(clipPlane);
  clipper->SetInputData(reader->GetOutput());
  clipper->SetValue(0.0);
  clipper->GenerateClippedOutputOn();
  clipper->Update();

  auto insideMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  insideMapper->SetInputData(clipper->GetOutput());
  insideMapper->ScalarVisibilityOff();

  auto insideActor =
    vtkSmartPointer<vtkActor>::New();
  insideActor->SetMapper(insideMapper);
  insideActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("banana").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  insideActor->GetProperty()->EdgeVisibilityOn();

  auto clippedMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  clippedMapper->SetInputData(clipper->GetClippedOutput());
  clippedMapper->ScalarVisibilityOff();

  auto clippedActor =
    vtkSmartPointer<vtkActor>::New();
  clippedActor->SetMapper(clippedMapper);
  clippedActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("tomato").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  clippedActor->GetProperty()->EdgeVisibilityOn();

  // Create transforms to make a better visualization
  auto insideTransform = vtkSmartPointer<vtkTransform>::New();
  insideTransform->Translate(-(bounds[1] - bounds[0]) * .75, 0, 0);
  insideTransform->Translate(center[0], center[1], center[2]);
  insideTransform->RotateY(-120.0);
  insideTransform->Translate(-center[0], -center[1], -center[2]);
  insideActor->SetUserTransform(insideTransform);

  auto clippedTransform = vtkSmartPointer<vtkTransform>::New();
  clippedTransform->Translate((bounds[1] - bounds[0]) * .75, 0, 0);
  clippedTransform->Translate(center[0], center[1], center[2]);
  clippedTransform->RotateY(60.0);
  clippedTransform->Translate(-center[0], -center[1], -center[2]);
  clippedActor->SetUserTransform(clippedTransform);

  renderer->AddViewProp(clippedActor);
  renderer->AddViewProp(insideActor);

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Dolly(1.4);
  renderer->ResetCameraClippingRange();
  renderWindow->Render();
  renderWindow->SetWindowName("ClipUnstructuredGridWithPlane");
  renderWindow->Render();

  interactor->Start();

  // Generate a report
  vtkIdType numberOfCells = clipper->GetOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The inside dataset contains a " << std::endl
            << clipper->GetOutput()->GetClassName()
            <<  " that has " << numberOfCells << " cells" << std::endl;
  typedef std::map<int,int> CellContainer;
  CellContainer cellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    cellMap[clipper->GetOutput()->GetCellType(i)]++;
  }

  for (auto c : cellMap)
  {
    std::cout << "\tCell type "
              << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }

  numberOfCells = clipper->GetClippedOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The clipped dataset contains a " << std::endl
            << clipper->GetClippedOutput()->GetClassName()
            <<  " that has " << numberOfCells << " cells" << std::endl;
  typedef std::map<int,int> OutsideCellContainer;
  CellContainer outsideCellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    outsideCellMap[clipper->GetClippedOutput()->GetCellType(i)]++;
  }

  for (auto c : outsideCellMap)
  {
    std::cout << "\tCell type "
              << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }
  return EXIT_SUCCESS;
}

实例2：ClipUnstructuredGridWithPlane2

该实例使用vtkClipDataSet对vtkUnstructuredGrid数据集进行Clip。vtkClipDataSet在未Clip的部位不会保留原有的Cells。与实例1比较，该实例在未Clip的区域将原有的vtkHexahedron转换成了vtkTetra。该实例的结果vtkUnstructuredGrid数据集的Cells数量比之前增加了四倍。

输入：treemesh.vtk

#include <vtkSmartPointer.h>
#include <vtkClipDataSet.h>
#include <vtkUnstructuredGridReader.h>
#include <vtkUnstructuredGrid.h>
#include <vtkPlane.h>
#include <vtkTransform.h>

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkCellTypes.h>
#include <vtkDataSetMapper.h>
#include <vtkLookupTable.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <vtkNamedColors.h>

int main(int argc, char *argv[])
{
  if (argc < 2)
  {
    std::cout << "Usage: " << argv[0] << " filename.vtk" << std::endl;
    return EXIT_FAILURE;
  }
  // Create the reader for the data.
  std::string filename = argv[1];
  std::cout << "Loading " << filename.c_str() << std::endl;
  auto reader =
    vtkSmartPointer<vtkUnstructuredGridReader>::New();
  reader->SetFileName(filename.c_str());
  reader->Update();

  double bounds[6];
  reader->GetOutput()->GetBounds(bounds);  
  double center[3];
  reader->GetOutput()->GetCenter(center);  

  auto colors =
    vtkSmartPointer<vtkNamedColors>::New();
  auto renderer = vtkSmartPointer<vtkRenderer>::New();
  renderer->SetBackground(colors->GetColor3d("Wheat").GetData());
  renderer->UseHiddenLineRemovalOn();

  auto renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderWindow->SetSize(640, 480);

  auto interactor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  interactor->SetRenderWindow(renderWindow);

  double xnorm[3] = {-1.0, -1.0, 1.0};

  auto clipPlane = vtkSmartPointer<vtkPlane>::New();
  clipPlane->SetOrigin(reader->GetOutput()->GetCenter());
  clipPlane->SetNormal(xnorm);

  auto clipper =
    vtkSmartPointer<vtkClipDataSet>::New();
  clipper->SetClipFunction(clipPlane);
  clipper->SetInputData(reader->GetOutput());
  clipper->SetValue(0.0);
  clipper->GenerateClippedOutputOn();
  clipper->Update();

  auto insideMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  insideMapper->SetInputData(clipper->GetOutput());
  insideMapper->ScalarVisibilityOff();

  auto insideActor =
    vtkSmartPointer<vtkActor>::New();
  insideActor->SetMapper(insideMapper);
  insideActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("banana").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  insideActor->GetProperty()->EdgeVisibilityOn();

  auto clippedMapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  clippedMapper->SetInputData(clipper->GetClippedOutput());
  clippedMapper->ScalarVisibilityOff();

  auto clippedActor =
    vtkSmartPointer<vtkActor>::New();
  clippedActor->SetMapper(clippedMapper);
  clippedActor->GetProperty()->SetDiffuseColor(colors->GetColor3d("tomato").GetData());
  insideActor->GetProperty()->SetAmbient(.3);
  clippedActor->GetProperty()->EdgeVisibilityOn();

  // Create transforms to make a better visualization
  auto insideTransform = vtkSmartPointer<vtkTransform>::New();
  insideTransform->Translate(-(bounds[1] - bounds[0]) * .75, 0, 0);
  insideTransform->Translate(center[0], center[1], center[2]);
  insideTransform->RotateY(-120.0);
  insideTransform->Translate(-center[0], -center[1], -center[2]);
  insideActor->SetUserTransform(insideTransform);

  auto clippedTransform = vtkSmartPointer<vtkTransform>::New();
  clippedTransform->Translate((bounds[1] - bounds[0]) * .75, 0, 0);
  clippedTransform->Translate(center[0], center[1], center[2]);
  clippedTransform->RotateY(60.0);
  clippedTransform->Translate(-center[0], -center[1], -center[2]);
  clippedActor->SetUserTransform(clippedTransform);

  renderer->AddViewProp(clippedActor);
  renderer->AddViewProp(insideActor);

  renderer->ResetCamera();
  renderer->GetActiveCamera()->Dolly(1.4);
  renderer->ResetCameraClippingRange();
  renderWindow->Render();
  renderWindow->SetWindowName("ClipUnstructuredGridWithPlane2");
  renderWindow->Render();

  interactor->Start();

  // Generate a report
  vtkIdType numberOfCells = clipper->GetOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The inside dataset contains a " << std::endl
            << clipper->GetOutput()->GetClassName()
            <<  " that has " << numberOfCells << " cells" << std::endl;
  typedef std::map<int,int> CellContainer;
  CellContainer cellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    cellMap[clipper->GetOutput()->GetCellType(i)]++;
  }

  for (auto c : cellMap)
  {
    std::cout << "\tCell type "
              << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }

  numberOfCells = clipper->GetClippedOutput()->GetNumberOfCells();
  std::cout << "------------------------" << std::endl;
  std::cout << "The clipped dataset contains a " << std::endl
            << clipper->GetClippedOutput()->GetClassName()
            <<  " that has " << numberOfCells << " cells" << std::endl;
  typedef std::map<int,int> OutsideCellContainer;
  CellContainer outsideCellMap;
  for (vtkIdType i = 0; i < numberOfCells; i++)
  {
    outsideCellMap[clipper->GetClippedOutput()->GetCellType(i)]++;
  }

  for (auto c : outsideCellMap)
  {
    std::cout << "\tCell type "
              << vtkCellTypes::GetClassNameFromTypeId(c.first)
              << " occurs " << c.second << " times." << std::endl;
  }
  return EXIT_SUCCESS;
}