Question

我使用了vtkDijkstraGraphGeodesicPath类（例如：http://www.cmake.org/Wiki/VTK/Examples/Cxx/PolyData/DijkstraGraphGeodesicPath）来找到网格上两点之间的最短路径，我的下一步是将路径（曲线）投影到平面。在vtk中是否有类或函数将曲线投影到平面？另一种方法是对路径（曲线）进行采样，然后将采样点投影到平面，那么如何对曲线进行采样并获取采样点？提前谢谢！

Answer 1

我从未找到过投影3D网格的方法，但我必须使用它，并且我选择了纹理化方法，允许在Plane / Cylinder / Sphere上投影网格（到texzturize）。

本案例中使用的主要方法是vtkTextureMapToPlane。

// your mesh
vtkSmartPointer<vtkPolyData> mainMesh = myFilter->GetOutput ();

// extract your path from the poly data

// retrieve selected ids from dijkstra algo
vtkSmartPointer<vtkIdList> idList = dijkstra->GetIdList ();
vtkSmartPointer<vtkIdTypeArray> ids = convertToIdTypeArr (idList); // custom method to convert id array

// Once the ID selections is done, the extraction is invoked
vtkSmartPointer<vtkSelectionNode> selectionNode = vtkSelectionNode::New ();
selectionNode->SetFieldType (vtkSelectionNode::POINT);
selectionNode->SetContentType (vtkSelectionNode::INDICES);
selectionNode->SetSelectionList (ids);
vtkSmartPointer<vtkSelection> selection = vtkSelection::New ();
selection->AddNode (selectionNode);

vtkSmartPointer<vtkExtractSelection> extract = vtkExtractSelection::New ();
extract->SetInputData (0, pl);
extract->SetInputData (1, selection);

// convert result to polydata
vtkSmartPointer<vtkGeometryFilter> geoFilter = vtkGeometryFilter::New ();
geoFilter->SetInputConnection (extract->GetOutputPort());
geoFilter->Update();
vtkSmartPointer<vtkPolyData> selected = geoFilter->GetOutput();

您有一个vtkpolyData来自路径的顶点。您需要创建平面和项目

// plane is sized with 800x600, on y-z directions
double orig[3] = {0, 0, 0};
double pt1[3] = {0, 600, 0};
double pt2[3] = {0, 0, 800};

// create TextureMapToPlan instance
vtkSmartPointer<vtkTextureMapToPlane> planeMapper = vtkTextureMapToPlane::New ();
planeMapper->SetOrigin(orig);
planeMapper->SetPoint1(pt1);
planeMapper->SetPoint2(pt2);

planeMapper->SetInputData (selected);
planeMapper->Update (); // project
vtkSmartPointer<vtkPolyData> d = planeMapper->GetPolyDataOutput(); // retrieve result

由于此算法用于纹理化，您需要检索纹理坐标，并将它们转换为平面坐标。（文本坐标以[0,1]的高度和宽度比定义）

vtkSmartPointer<vtkDataArray> textCoord = d->GetPointData()->GetTCoords ();
vtkSmartPointer <vtkPoints> textPoints = vtkPoints::New ();
for (int i = 0; i < textCoord->GetNumberOfTuples (); ++i)
 {
    textPoints->InsertNextPoint (textCoord->GetTuple2(i)[0] * 800,
                                   textCoord->GetTuple2(i)[1] * 600, 0);
 }

textPoints在这里得到了你在飞机上的路径投影的二维中的所有坐标。 /！\这个坐标取决于您的平面坐标。

如何在vtk中将曲线投影到平面

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