1.点配准
在计算机逆向工程中，各种点云数据可以通过三维扫描等物理数字技术获得。然而，由于测量环境和设备的影响，在再次测量的情况下，很难获得数据，因此需要从不同的角度进行多次测量。但在不同的测量数据之间可能存在平移错误或旋转错位。这是利用点云匹配技术整合测量点云数据的局部匹配，以获得完整的模型数据。 此外，在手术导航技术中，图像标记技术与人体表面标记点的匹配是一个关键步骤，对手术定位的精度有重要影响。通常，这需要基于标记点的匹配技术。因此，点云匹配及时转换一组源云数据，使转换后的数据和目标点云数据能够逐一映射，使两组数据之间的平均距离误差最小化。
2.LandMark配准实验
VTKLandMarkTransform实现了片几点配准算法，使得两个点集在配准后平均距离最小。通过SetSourceLandmarks()设置源标记点的位置，SetTargetLandmarks()函数设计目标标记点的位置。需要注意的是，源标记点集与目标标记点集序号相对应。
#include <vtkAutoInit.h> VTK_MODULE_INIT(vtkRenderingOpenGL2); VTK_MODULE_INIT(vtkRenderingFreeType); VTK_MODULE_INIT(vtkInteractionStyle); #include <vtkSmartPointer.h> #include <vtkPoints.h> #include <vtkLandmarkTransform.h> #include <vtkPolyData.h> #include <vtkVertexGlyphFilter.h> #include <vtkTransformPolyDataFilter.h> #include <vtkPolyDataMapper.h> #include <vtkActor.h> #include <vtkProperty.h> #include <vtkRenderer.h> #include <vtkRenderWindow.h> #include <vtkRenderWindowInteractor.h> #include <vtkAxesActor.h> ///研究坐标系显示位置 #include <vtkOrientationMarkerWidget.h> int main() { vtkSmartPointer<vtkPoints> sourcePoints = vtkSmartPointer<vtkPoints>::New(); double sourcePoint1[3] = { 0.5, 0, 0 }; sourcePoints->InsertNextPoint(sourcePoint1); double sourcePoint2[3] = { 0, 0.5, 0 }; sourcePoints->InsertNextPoint(sourcePoint2); double sourcePoint3[3] = { 0, 0, 0.5 }; sourcePoints->InsertNextPoint(sourcePoint3); vtkSmartPointer<vtkPoints> targetPoints = vtkSmartPointer<vtkPoints>::New(); double targetPoint1[3] = { 0.0, 0.0, 0.55 }; targetPoints->InsertNextPoint(targetPoint1); double targetPoint2[3] = { 0.0, 0.55, 0.0 }; targetPoints->InsertNextPoint(targetPoint2); double targetPoint3[3] = { -0.55, 0.0, 0.0 }; targetPoints->InsertNextPoint(targetPoint3); //利用Landmark算法求变换矩阵 vtkSmartPointer<vtkLandmarkTransform> landmarkTransform = vtkSmartPointer<vtkLandmarkTransform>::New(); landmarkTransform->SetSourceLandmarks(sourcePoints); landmarkTransform->SetTargetLandmarks(targetPoints); landmarkTransform->SetModeToRigidBody(); //执行刚体配准 landmarkTransform->Update(); //构造PolyData类型 进行图形可视化 vtkSmartPointer<vtkPolyData> source = vtkSmartPointer<vtkPolyData>::New(); source->SetPoints(sourcePoints); vtkSmartPointer<vtkPolyData> target = vtkSmartPointer<vtkPolyData>::New(); target->SetPoints(targetPoints); // vtkSmartPointer<vtkVertexGlyphFilter> sourceGlyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New(); sourceGlyphFilter->SetInputData(source); sourceGlyphFilter->Update(); vtkSmartPointer<vtkVertexGlyphFilter> targetGlyphFilter = vtkSmartPointer<vtkVertexGlyphFilter>::New(); targetGlyphFilter->SetInputData(target); targetGlyphFilter->Update(); //源数据施加配准变换矩阵 vtkSmartPointer<vtkTransformPolyDataFilter> transformFilter = vtkSmartPointer<vtkTransformPolyDataFilter>::New(); transformFilter->SetInputData(sourceGlyphFilter->GetOutput()); transformFilter->SetTransform(landmarkTransform); transformFilter->Update(); // vtkSmartPointer<vtkPolyDataMapper> sourceMapper = vtkSmartPointer<vtkPolyDataMapper>::New(); sourceMapper->SetInputConnection(sourceGlyphFilter->GetOutputPort()); vtkSmartPointer<vtkActor> sourceActor = vtkSmartPointer<vtkActor>::New(); sourceActor->SetMapper(sourceMapper); sourceActor->GetProperty()->SetColor(1, 1, 0); sourceActor->GetProperty()->SetPointSize(10); vtkSmartPointer<vtkPolyDataMapper> targetMapper = vtkSmartPointer<vtkPolyDataMapper>::New(); targetMapper->SetInputConnection(targetGlyphFilter->GetOutputPort()); vtkSmartPointer<vtkActor> targetActor = vtkSmartPointer<vtkActor>::New(); targetActor->SetMapper(targetMapper); targetActor->GetProperty()->SetColor(0, 1, 0); targetActor->GetProperty()->SetPointSize(10); vtkSmartPointer<vtkPolyDataMapper> solutionMapper = vtkSmartPointer<vtkPolyDataMapper>::New(); solutionMapper->SetInputConnection(transformFilter->GetOutputPort()); vtkSmartPointer<vtkActor> solutionActor = vtkSmartPointer<vtkActor>::New(); solutionActor->SetMapper(solutionMapper); solutionActor->GetProperty()->SetColor(1, 0, 0); solutionActor->GetProperty()->SetPointSize(10); vtkSmartPointer<vtkRenderer> render = vtkSmartPointer<vtkRenderer>::New(); render->AddActor(sourceActor); render->AddActor(targetActor); render->AddActor(solutionActor); render->SetBackground(0, 0, 0); vtkSmartPointer<vtkRenderWindow> rw = vtkSmartPointer<vtkRenderWindow>::New(); rw->AddRenderer(render); rw->SetSize(480, 480); rw->SetWindowName("Regisration by Landmark"); //设置坐标系显示功能 vtkSmartPointer<vtkAxesActor> axes = vtkSmartPointer<vtkAxesActor>::New(); axes->SetScale(10); render->AddActor(axes); vtkSmartPointer<vtkRenderWindowInteractor> rwi = vtkSmartPointer<vtkRenderWindowInteractor>::New(); rwi->SetRenderWindow(rw); /************************************************************/ vtkSmartPointer<vtkOrientationMarkerWidget> widget = vtkSmartPointer<vtkOrientationMarkerWidget>::New(); widget->SetOutlineColor(0.9300, 0.5700, 0.1300); widget->SetOrientationMarker(axes); widget->SetInteractor(rwi); //加入鼠标交互 widget->SetViewport(0.0, 0.0, 0.3, 0.3); //设置显示位置 widget->SetEnabled(1); widget->InteractiveOn();//开启鼠标交互 /************************************************************/ render->ResetCamera(); rw->Render(); rwi->Initialize(); rwi->Start(); return 0; }
黄色散点代表代表配准点集；绿色散点代表金标准；红色散点代表施加变换矩阵后的源数据点集。 vtkVertexGliphFilter类显示点集！VTKTransformPolyDataFilter用来对源点标记点进行变换来显示配准后的点集，SetTransform（）函数直接设置为vtkLandmarkTransform的变换结果。 
2.VTKLandmarkTransform类
VTKLandmarkTraTransform类的使用比较简单，只要设定源标记点和目标标记点。SetModeToRigidBody（）函数用于设置其配准变换类型为刚体变换，仅包括简单的平移和转换（6个自由的角度）。此外还有一个更为钢钒应用的函数——SetModeToSimilarity，设置为相似变换，包括平移、旋转和放缩变换（7个自由度）。以及SetModeToAffine()函数设置放射变换。默认情况，就采用相似变化进行配准。
3.vtkAxesActor类
在显示三维物体时，我们只希望知道当前对应的坐标位置或者方向，这样在旋转物体的时候，就能够很清楚地看见当前正对 //设置坐标系显示功能
vtkSmartPointer<vtkAxesActor> axes =
vtkSmartPointer<vtkAxesActor>::New();
axes->SetScale(10);
render->AddActor(axes);视野的XY平面，或者是Y轴的信息。