VTK图像处理之vtkImageReslice |
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VTK图像处理之vtkImageReslice
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VTK图像处理之vtkImageReslice vtk类之vtkImageReslice：基本算法，对体数据沿着轴进行切片 VTK/Tutorials/Extents
切片（Slice）或切面是三维图像比较常用的概念，尤其在医学图像中。通过提取切面可以方便地浏览和分析图像内部组织结构。VTK中vtkImageReSlice类可以实现图像切面的提取。在实际开发中，四视图中冠状视面、矢状面和横断面（显示过图像内部一点且平行于XY、YZ、XZ平面的平面），需要用到此类。 在显示图像时，很多时候我们需要的不是矢状面，冠状面或者横断面这种与坐标轴平行的正交面，而是一些斜切面。这时候就可以利用vtkImageReslice 这个类来实现。 这个类的输入最主要的是SetResliceAxes()这个函数，这个函数的输入是vtkMatrix4x4 其代表的是新的坐标系在世界坐标系下的坐标值。可以把vtkMatrix4x4看成是4列，其中第一，二，三列分别为新的坐标系在世界坐标系下的向量坐标，第四列代表的是新的坐标原点在世界坐标系下的坐标值。如下面的四列值就表示新的坐标系原点为（100,200,10），x方向向量坐标为（1,0,0），y方向向量坐标为（0,0,-1），z方向向量坐标为（0,1,0）。 1,0,0,100 0,0,1,200 0,-1,0,10 0,0,0,1 要注意的是这三个法向量要满足右手法则，即X叉乘Y为Z，Y叉乘Z为X，Z叉乘X为Y。如果不满足这个规则，得到的坐标系就不符合右手法则，得不到想要的切面。 另外通过reslice->SetSlabModeToSum();可以得到类似于DRR的图像效果。 最后通过GetOutput函数获得vtkImageData 示例说明 CMakeLists.txt文件代码如下： CMAKE_MINIMUM_REQUIRED(VERSION 2.8) PROJECT(ImageResliceExample) FIND_PACKAGE(VTK REQUIRED) INCLUDE(${VTK_USE_FILE}) ADD_EXECUTABLE(ImageResliceExample ImageResliceExample.cpp) TARGET_LINK_LIBRARIES(ImageResliceExample ${VTK_LIBRARIES}) ImageResliceExample.cpp文件代码如下： #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include class vtkImageInteractionCallback : public vtkCommand { public: static vtkImageInteractionCallback *New() { return new vtkImageInteractionCallback; } vtkImageInteractionCallback() { this->Slicing = 0; this->ImageReslice = 0; this->Interactor = 0; } void SetImageReslice(vtkImageReslice *reslice) { this->ImageReslice = reslice; } void SetImageMapToColors(vtkImageMapToColors *mapToColors) { this->mapToColors = mapToColors; } vtkImageReslice *GetImageReslice() { return this->ImageReslice; } void SetInteractor(vtkRenderWindowInteractor *interactor) { this->Interactor = interactor; } vtkRenderWindowInteractor *GetInteractor() { return this->Interactor; } virtual void Execute(vtkObject *, unsigned long event, void *) { vtkRenderWindowInteractor *interactor = this->GetInteractor(); int lastPos[2]; interactor->GetLastEventPosition(lastPos); int currPos[2]; interactor->GetEventPosition(currPos); if (event == vtkCommand::LeftButtonPressEvent) { this->Slicing = 1; } else if (event == vtkCommand::LeftButtonReleaseEvent) { this->Slicing = 0; } else if (event == vtkCommand::MouseMoveEvent) { if (this->Slicing) { vtkImageReslice *reslice = this->ImageReslice; // Increment slice position by deltaY of mouse int deltaY = lastPos[1] - currPos[1]; reslice->Update(); double sliceSpacing = reslice->GetOutput()->GetSpacing()[2]; vtkMatrix4x4 *matrix = reslice->GetResliceAxes(); // move the center point that we are slicing through double point[4]; double center[4]; point[0] = 0.0; point[1] = 0.0; point[2] = sliceSpacing * deltaY; point[3] = 1.0; matrix->MultiplyPoint(point, center); matrix->SetElement(0, 3, center[0]); matrix->SetElement(1, 3, center[1]); matrix->SetElement(2, 3, center[2]); mapToColors->Update(); interactor->Render(); } else { vtkInteractorStyle *style = vtkInteractorStyle::SafeDownCast( interactor->GetInteractorStyle()); if (style) { style->OnMouseMove(); } } } } private: int Slicing; vtkImageReslice *ImageReslice; vtkRenderWindowInteractor *Interactor; vtkImageMapToColors *mapToColors; }; int main() { vtkSmartPointer reader = vtkSmartPointer::New(); reader->SetFileName ( "E:\\TestData\\brain.mhd" ); reader->Update(); int extent[6]; double spacing[3]; double origin[3]; reader->GetOutput()->GetExtent(extent); reader->GetOutput()->GetSpacing(spacing); reader->GetOutput()->GetOrigin(origin); double center[3]; center[0] = origin[0] + spacing[0] * 0.5 * (extent[0] + extent[1]); center[1] = origin[1] + spacing[1] * 0.5 * (extent[2] + extent[3]); center[2] = origin[2] + spacing[2] * 0.5 * (extent[4] + extent[5]); static double axialElements[16] = { 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1 }; vtkSmartPointer resliceAxes = vtkSmartPointer::New(); resliceAxes->DeepCopy(axialElements); resliceAxes->SetElement(0, 3, center[0]); resliceAxes->SetElement(1, 3, center[1]); resliceAxes->SetElement(2, 3, center[2]); vtkSmartPointer reslice = vtkSmartPointer::New(); reslice->SetInputConnection(reader->GetOutputPort()); reslice->SetOutputDimensionality(2); reslice->SetResliceAxes(resliceAxes); reslice->SetInterpolationModeToLinear(); vtkSmartPointer colorTable = vtkSmartPointer::New(); colorTable->SetRange(0, 1000); colorTable->SetValueRange(0.0, 1.0); colorTable->SetSaturationRange(0.0, 0.0); colorTable->SetRampToLinear(); colorTable->Build(); vtkSmartPointer colorMap = vtkSmartPointer::New(); colorMap->SetLookupTable(colorTable); colorMap->SetInputConnection(reslice->GetOutputPort()); colorMap->Update(); vtkSmartPointer imgActor = vtkSmartPointer::New(); imgActor->SetInputData(colorMap->GetOutput()); vtkSmartPointer renderer = vtkSmartPointer::New(); renderer->AddActor(imgActor); renderer->SetBackground(1, 1, 1); vtkSmartPointer renderWindow = vtkSmartPointer::New(); renderWindow->SetSize(500, 500); renderWindow->AddRenderer(renderer); vtkSmartPointer renderWindowInteractor = vtkSmartPointer::New(); vtkSmartPointer imagestyle = vtkSmartPointer::New(); renderWindowInteractor->SetInteractorStyle(imagestyle); renderWindowInteractor->SetRenderWindow(renderWindow); renderWindowInteractor->Initialize(); vtkSmartPointer callback = vtkSmartPointer::New(); callback->SetImageReslice(reslice); callback->SetInteractor(renderWindowInteractor); callback->SetImageMapToColors(colorMap); imagestyle->AddObserver(vtkCommand::MouseMoveEvent, callback); imagestyle->AddObserver(vtkCommand::LeftButtonPressEvent, callback); imagestyle->AddObserver(vtkCommand::LeftButtonReleaseEvent, callback); renderWindowInteractor->Start(); return EXIT_SUCCESS; } 运行结果：按下鼠标左键，移动鼠标时的gif图片： |
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