关于VTK的三维重建
我在网上down了一份代码，附在最后，能够运行
但是，我还是对这个三维重建的过程有点不理解，求大神给稍微讲讲，三维重建的一些步骤
就比如说，代码中有这么一段：
vtkPolyDataNormals *skinNormals = vtkPolyDataNormals::New();
skinNormals->SetInputConnection(skinExtractor->GetOutputPort());
skinNormals->SetFeatureAngle(120.0);
vtkPolyDataMapper *skinMapper = vtkPolyDataMapper::New();
skinMapper->SetInputConnection(skinNormals->GetOutputPort());
skinMapper->ScalarVisibilityOff();
这个vtkPolyDataNormals是要求法线吗？不明白为什么重建还要求法线，它的用途是什么？
#include "vtkRenderer.h"VTK 三维重建
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkDICOMImageReader.h"
#include "vtkPolyDataMapper.h"
#include "vtkActor.h"
#include "vtkOutlineFilter.h"
#include "vtkCamera.h"
#include "vtkProperty.h"
#include "vtkPolyDataNormals.h"
#include "vtkContourFilter.h"
void main ()
{
vtkRenderer *aRenderer = vtkRenderer::New();
vtkRenderWindow *renWin = vtkRenderWindow::New();
renWin->AddRenderer(aRenderer);
vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
iren->SetRenderWindow(renWin);
vtkDICOMImageReader *v16 = vtkDICOMImageReader::New();
v16->SetDataByteOrderToLittleEndian();
v16->SetDirectoryName("C:\\Users\\zhq\\Desktop\\data\\SNAP_CR\\E403434298"); //文件所在的位置
v16->SetDataSpacing (3.2, 3.2, 1.5);
// An isosurface, or contour value of 500 is known to correspond to the
// skin of the patient. Once generated, a vtkPolyDataNormals filter is
// is used to create normals for smooth surface shading during rendering.
vtkContourFilter *skinExtractor = vtkContourFilter::New();
skinExtractor->SetInputConnection(v16->GetOutputPort());
skinExtractor->SetValue(0, 400);
vtkPolyDataNormals *skinNormals = vtkPolyDataNormals::New();
skinNormals->SetInputConnection(skinExtractor->GetOutputPort());
skinNormals->SetFeatureAngle(120.0);
vtkPolyDataMapper *skinMapper = vtkPolyDataMapper::New();
skinMapper->SetInputConnection(skinNormals->GetOutputPort());
skinMapper->ScalarVisibilityOff();
vtkActor *skin = vtkActor::New();
skin->SetMapper(skinMapper);
// An outline provides context around the data.
//
vtkOutlineFilter *outlineData = vtkOutlineFilter::New();
outlineData->SetInputConnection(v16->GetOutputPort());
vtkPolyDataMapper *mapOutline = vtkPolyDataMapper::New();
mapOutline->SetInputConnection(outlineData->GetOutputPort());
vtkActor *outline = vtkActor::New();
outline->SetMapper(mapOutline);
outline->GetProperty()->SetColor(0,0,0);
// It is convenient to create an initial view of the data. The FocalPoint
// and Position form a vector direction. Later on (ResetCamera() method)
// this vector is used to position the camera to look at the data in
// this direction.
vtkCamera *aCamera = vtkCamera::New();
aCamera->SetViewUp (0, 0, -1);
aCamera->SetPosition (0, 1, 0);
aCamera->SetFocalPoint (0, 0, 0);
aCamera->ComputeViewPlaneNormal();
// Actors are added to the renderer. An initial camera view is created.
// The Dolly() method moves the camera towards the FocalPoint,
// thereby enlarging the image.
aRenderer->AddActor(outline);
aRenderer->AddActor(skin);
aRenderer->SetActiveCamera(aCamera);
aRenderer->ResetCamera ();
aCamera->Dolly(1.5);
// Set a background color for the renderer and set the size of the
// render window (expressed in pixels).
aRenderer->SetBackground(1,1,1);
renWin->SetSize(640, 480);
// Note that when camera movement occurs (as it does in the Dolly()
// method), the clipping planes often need adjusting. Clipping planes
// consist of two planes: near and far along the view direction. The
// near plane clips out objects in front of the plane; the far plane
// clips out objects behind the plane. This way only what is drawn
// between the planes is actually rendered.
aRenderer->ResetCameraClippingRange ();
// Initialize the event loop and then start it.
iren->Initialize();
iren->Start();
v16->Delete();
skinExtractor->Delete();
skinNormals->Delete();
skinMapper->Delete();
skin->Delete();
outlineData->Delete();
mapOutline->Delete();
outline->Delete();
aCamera->Delete();
iren->Delete();
renWin->Delete();
aRenderer->Delete();
}
