VTK中对模型进行封闭性检测

最新推荐文章于 2025-11-09 05:48:18 发布

原创最新推荐文章于 2025-11-09 05:48:18 发布 · 2.6k 阅读

14 ·

CC 4.0 BY-SA版权

VTK 专栏收录该内容

6 篇文章

订阅专栏

本文介绍如何使用VTK库中的vtkFeatureEdges类检测三维网格模型的封闭性，通过提取边界边判断模型是否封闭，并利用vtkFillHolesFilter进行漏洞填补，确保模型封闭。

由于受原始数据、重建方法的限制，得到的网格模型并不是封闭的。有时为了显示或者处理某些要求，需要网格必须是封闭的。比如一个球面网格就是封闭性网格。

如果一条边只被一个多边形包含，那么这条边就是边界边。是否存在边界边是检测一个网格模型是否封闭的重要特征。vtkFeatureEdges是一个非常重要的类，该类能够提取多边形网格模型中四种类型的边：

边界边：即只被一个多边形或者一条边包含的边。
非流形边：被3个或者3个以上的多边形包含的边。
特征边：需设置一个特征角的阈值，当包含同一条边的两个三角形的法向量的夹角大于该阈值时，即为一个特征边。
流形边：只被两个多边形包含的边。

可以使用该类来检测是否存在边界边，并以此来判断网格模型是否封闭，代码如下：

#include <vtkSmartPointer.h>
#include <vtkSelectionNode.h>
#include <vtkInformation.h>
#include <vtkUnstructuredGrid.h>
#include <vtkPolyData.h>
#include <vtkPolyDataNormals.h>
#include <vtkPointData.h>
#include <vtkXMLPolyDataReader.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSelection.h>
#include <vtkSelectionNode.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkProperty.h>
#include <vtkIdTypeArray.h>
#include <vtkExtractSelection.h>
#include <vtkDataSetSurfaceFilter.h>
#include <vtkFeatureEdges.h>
#include <vtkFillHolesFilter.h>

void GenerateData(vtkSmartPointer<vtkPolyData> input)
{
	// 以下代码是创建一个球面网格，并去除两个三角面片
    vtkSmartPointer<vtkSphereSource> sphereSource =
		vtkSmartPointer<vtkSphereSource>::New();
	sphereSource->Update();
    
    // 根据索引选择要被去除两个三角面片
	vtkSmartPointer<vtkIdTypeArray> ids =
		vtkSmartPointer<vtkIdTypeArray>::New();
	ids->SetNumberOfComponents(1);
	ids->InsertNextValue(2);
	ids->InsertNextValue(10);

    // 选择点，注意Set(vtkSelectionNode::INVERSE(), 1)中的INVERSE(),这是反选
	vtkSmartPointer<vtkSelectionNode> selectionNode =
		vtkSmartPointer<vtkSelectionNode>::New();
	selectionNode->SetFieldType(vtkSelectionNode::CELL);
	selectionNode->SetContentType(vtkSelectionNode::INDICES);
	selectionNode->SetSelectionList(ids);
	selectionNode->GetProperties()->Set(vtkSelectionNode::INVERSE(), 1);

	vtkSmartPointer<vtkSelection> selection =
		vtkSmartPointer<vtkSelection>::New();
	selection->AddNode(selectionNode);

	vtkSmartPointer<vtkExtractSelection> extractSelection =
		vtkSmartPointer<vtkExtractSelection>::New();
	extractSelection->SetInputData(0, sphereSource->GetOutput());
	extractSelection->SetInputData(1, selection);
	extractSelection->Update();

	vtkSmartPointer<vtkDataSetSurfaceFilter> surfaceFilter =
		vtkSmartPointer<vtkDataSetSurfaceFilter>::New();
	surfaceFilter->SetInputConnection(extractSelection->GetOutputPort());
	surfaceFilter->Update();

	input->ShallowCopy(surfaceFilter->GetOutput());
}

int main(int argc, char *argv[])
{
	vtkSmartPointer<vtkPolyData> input =
		vtkSmartPointer<vtkPolyData>::New();
	GenerateData(input);

    // 特征边提取
	vtkSmartPointer<vtkFeatureEdges> featureEdges =
		vtkSmartPointer<vtkFeatureEdges>::New();
	featureEdges->SetInputData(input);
	featureEdges->BoundaryEdgesOn();
	featureEdges->FeatureEdgesOff();
	featureEdges->ManifoldEdgesOff();
	featureEdges->NonManifoldEdgesOff();
	featureEdges->Update();

    // 根据特征边的数量判断是否封闭
	int numberOfOpenEdges = featureEdges->GetOutput()->GetNumberOfCells();
	if(numberOfOpenEdges) 
	{
		std::cout<<"该网格模型不是封闭的..."<<std::endl;
	}
	else
	{
		std::cout<<"该网格模型是封闭的..."<<std::endl;
		return EXIT_SUCCESS;
	}

    // 如果不封闭，使用vtkFillHolesFilter将模型封闭
	vtkSmartPointer<vtkFillHolesFilter> fillHolesFilter =
		vtkSmartPointer<vtkFillHolesFilter>::New();
	fillHolesFilter->SetInputData(input);
	fillHolesFilter->Update();

    // 经过漏洞填充，模型所有点的顺序并不一致，因此需要vtkPolyDataNormals类中
    // 的ConsistencyOn()使点的顺序一致，只有这样才能得到正确的法向量。法向量是
    // 与光照和阴影计算相关的。
	vtkSmartPointer<vtkPolyDataNormals> normals =
		vtkSmartPointer<vtkPolyDataNormals>::New();
	normals->SetInputConnection(fillHolesFilter->GetOutputPort());
	normals->ConsistencyOn();
	normals->SplittingOff();
	normals->Update();

	//////////////////////////////////////////////////////////////////////////
	double leftViewport[4] = {0.0, 0.0, 0.5, 1.0};
	double rightViewport[4] = {0.5, 0.0, 1.0, 1.0};

	vtkSmartPointer<vtkPolyDataMapper> originalMapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	originalMapper->SetInputData(input);

	vtkSmartPointer<vtkProperty> backfaceProp =
		vtkSmartPointer<vtkProperty>::New();
	backfaceProp->SetDiffuseColor(0.89,0.81,0.34);

	vtkSmartPointer<vtkActor> originalActor =
		vtkSmartPointer<vtkActor>::New();
	originalActor->SetMapper(originalMapper);
	originalActor->SetBackfaceProperty(backfaceProp);
	originalActor->GetProperty()->SetDiffuseColor(1.0, 0.3882, 0.2784);

	vtkSmartPointer<vtkPolyDataMapper> edgeMapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	edgeMapper->SetInputData(featureEdges->GetOutput());
	vtkSmartPointer<vtkActor> edgeActor =
		vtkSmartPointer<vtkActor>::New();
	edgeActor->SetMapper(edgeMapper);
	edgeActor->GetProperty()->SetEdgeColor(0.,0.,1.0);
	edgeActor->GetProperty()->SetEdgeVisibility(1);
	edgeActor->GetProperty()->SetLineWidth(5);

	vtkSmartPointer<vtkPolyDataMapper> filledMapper =
		vtkSmartPointer<vtkPolyDataMapper>::New();
	filledMapper->SetInputData(normals->GetOutput());

	vtkSmartPointer<vtkActor> filledActor =
		vtkSmartPointer<vtkActor>::New();
	filledActor->SetMapper(filledMapper);
	filledActor->GetProperty()->SetDiffuseColor(1.0, 0.3882, 0.2784);

	vtkSmartPointer<vtkRenderer> leftRenderer =
		vtkSmartPointer<vtkRenderer>::New();
	leftRenderer->SetViewport(leftViewport);
	leftRenderer->AddActor(originalActor);
	leftRenderer->AddActor(edgeActor);
	leftRenderer->SetBackground(1.0, 1.0, 1.0);

	vtkSmartPointer<vtkRenderer> rightRenderer =
		vtkSmartPointer<vtkRenderer>::New();
	rightRenderer->SetViewport(rightViewport);
	rightRenderer->AddActor(filledActor);
	rightRenderer->SetBackground(1.0, 1.0, 1.0);

	vtkSmartPointer<vtkRenderWindow> renderWindow =
		vtkSmartPointer<vtkRenderWindow>::New();
	renderWindow->AddRenderer(leftRenderer);
	renderWindow->AddRenderer(rightRenderer);
	renderWindow->SetSize(640, 320);
	renderWindow->Render();
	renderWindow->SetWindowName("PolyDataClosed");

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

	leftRenderer->GetActiveCamera()->SetPosition(0, -1, 0);
	leftRenderer->GetActiveCamera()->SetFocalPoint(0, 0, 0);
	leftRenderer->GetActiveCamera()->SetViewUp(0, 0, 1);
	leftRenderer->GetActiveCamera()->Azimuth(30);
	leftRenderer->GetActiveCamera()->Elevation(30);
	leftRenderer->ResetCamera();
	rightRenderer->SetActiveCamera(leftRenderer->GetActiveCamera());

	renderWindow->Render();
	renderWindowInteractor->Start();

	return EXIT_SUCCESS;
}

下图为运行结果，左图为原始模型，并将检测的边界用红色显示，右侧为漏洞填补后的结果。