VTK 体积可视化问题

Question

我正在使用带有 C++ 的 vtk 库来生成和可视化一些具有给定颜色和透明度映射的合成体素数据。一个例子如下所示：

如图，数据总体上是3D的，效果很好。但是，在特定情况下 当数据变为 2D 时，可视化 windows 什么都不显示。

我正在发布几行可能有用的代码。

imageData = vtkSmartPointer<vtkImageData>::New();
imageData->SetDimensions(X1, X2, X3); //For 2D, one of X1,X2 & X3=1
imageData->AllocateScalars(VTK_INT, 1);
int* I = new int[X1X2X3](); //int X1X2X3 = X1*X2*X3
I = static_cast<int*>(imageData->GetScalarPointer());

请注意，对于 2D，X1=1 或 X2=1 或 X3=1。有什么建议吗？

编辑： 我正在添加等效代码，它将演示我面临的确切问题：

main.cpp

//#include <vtkAutoInit.h> // if not using CMake to compile, necessary to use this macro
//#define vtkRenderingCore_AUTOINIT 3(vtkInteractionStyle, vtkRenderingFreeType, vtkRenderingOpenGL2)
//#define vtkRenderingVolume_AUTOINIT 1(vtkRenderingVolumeOpenGL2)
//#define vtkRenderingContext2D_AUTOINIT 1(vtkRenderingContextOpenGL2)
#include <vtkSmartPointer.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartVolumeMapper.h>
#include <vtkColorTransferFunction.h>
#include <vtkVolumeProperty.h>
#include <vtkSampleFunction.h>
#include <vtkPiecewiseFunction.h>
#include <vtkImageData.h>
#include <stdlib.h>
using namespace std;

int main()
{
    //Declaring Variables
    vtkSmartPointer<vtkImageData> imageData;
    vtkSmartPointer<vtkVolumeProperty> volumeProperty;
    vtkSmartPointer<vtkPiecewiseFunction> compositeOpacity;
    vtkSmartPointer<vtkColorTransferFunction> color;
    vtkSmartPointer<vtkVolume> volume;
    vtkSmartPointer<vtkSmartVolumeMapper> mapper;
    vtkSmartPointer<vtkActor> actor;
    vtkSmartPointer<vtkRenderer> renderer;
    vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor;
    vtkSmartPointer<vtkRenderWindow> renderWindow;
    int* I;
    int X1, X2, X3, X1X2X3;

    //Assigning Values , Allocating Memory
    X1 = 10;
    X2 = 10;
    X3 = 10;
    X1X2X3 = X1*X2*X3;
    I = new int[X1X2X3]();
    imageData = vtkSmartPointer<vtkImageData>::New();
    volumeProperty = vtkSmartPointer<vtkVolumeProperty>::New();
    compositeOpacity = vtkSmartPointer<vtkPiecewiseFunction>::New();
    color = vtkSmartPointer<vtkColorTransferFunction>::New();
    volume = vtkSmartPointer<vtkVolume>::New();
    mapper = vtkSmartPointer<vtkSmartVolumeMapper>::New();
    actor = vtkSmartPointer<vtkActor>::New();
    renderer = vtkSmartPointer<vtkRenderer>::New();
    renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
    renderWindow = vtkSmartPointer<vtkRenderWindow>::New(); 
    volumeProperty->ShadeOff();
    volumeProperty->SetInterpolationType(0);
    volumeProperty->SetColor(color);
    volumeProperty->SetScalarOpacity(compositeOpacity);
    imageData->SetDimensions(X1, X2, X3);
    imageData->AllocateScalars(VTK_INT, 1);
    I = static_cast<int*>(imageData->GetScalarPointer());
    renderWindow->AddRenderer(renderer);
    renderWindowInteractor->SetRenderWindow(renderWindow);
    renderer->SetBackground(0.5, 0.5, 0.5);
    renderWindow->SetSize(800, 800);    
    mapper->SetBlendModeToComposite();
    imageData->UpdateCellGhostArrayCache();
    mapper->SetRequestedRenderModeToRayCast();
    mapper->SetInputData(imageData);
    volume->SetMapper(mapper);
    volume->SetProperty(volumeProperty);
    renderer->AddViewProp(volume);
    volumeProperty->ShadeOff();

    //Setting Voxel Data and Its Properties
    for (int i = 0; i < X1X2X3; i++)
    {
        I[i] = i;
        compositeOpacity->AddPoint(i, 1);
        color->AddRGBPoint(i, double( rand()) / RAND_MAX, double(rand()) / RAND_MAX, double(rand()) / RAND_MAX);
    }

    renderer->ResetCamera();
    renderWindow->Render();
    renderWindowInteractor->Start();
    getchar();
    return 0;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.0)
project(EvoSim)
set(CMAKE_CXX_STANDARD 14)
set(CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS ON)
set(CMAKE_USE_RELATIVE_PATHS ON)
#GRABBING VTK
find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(MAIN main.cpp)
target_link_libraries(MAIN ${VTK_LIBRARIES})

这导致如下输出（对于，X1=X2=X3=10）

但是如果我让 X1=1，输出 window 是空的。

编辑：

我刚刚观察到，屏幕上显示的某个维度上的体素数总是比该维度上的最大体素数少一个。例如，如果 X1=X2=X3=10，则 vtkwindow 上显示的每个维度中的体素数为 9。这不是我所期望的。我认为这是X1=1的问题，使得1-1=0体素显示。有什么建议么？？

Answer 1

长期以来一直没有得到答复。所以我要添加我的 solution/workaround。我必须在图像数据的每个维度中添加一个额外的虚拟层。 [参见代码中的这一行 imageData->SetDimensions(X1 +1 , X2 + 1, X3 + 1);]。休息是不言自明的。

#pragma once
//#include <vtkAutoInit.h> // if not using CMake to compile, necessary to use this macro
//#define vtkRenderingCore_AUTOINIT 3(vtkInteractionStyle, vtkRenderingFreeType, vtkRenderingOpenGL2)
//#define vtkRenderingVolume_AUTOINIT 1(vtkRenderingVolumeOpenGL2)
//#define vtkRenderingContext2D_AUTOINIT 1(vtkRenderingContextOpenGL2)
#include <vtkSmartPointer.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartVolumeMapper.h>
#include <vtkColorTransferFunction.h>
#include <vtkVolumeProperty.h>
#include <vtkSampleFunction.h>
#include <vtkPiecewiseFunction.h>
#include <vtkImageData.h>
#include <stdlib.h>
#include <numeric>      // std::iota
using namespace std;

int main()
{
    //Declaring Variables
    vtkSmartPointer<vtkImageData> imageData;
    vtkSmartPointer<vtkVolumeProperty> volumeProperty;
    vtkSmartPointer<vtkPiecewiseFunction> compositeOpacity;
    vtkSmartPointer<vtkColorTransferFunction> color;
    vtkSmartPointer<vtkVolume> volume;
    vtkSmartPointer<vtkSmartVolumeMapper> mapper;
    vtkSmartPointer<vtkActor> actor;
    vtkSmartPointer<vtkRenderer> renderer;
    vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor;
    vtkSmartPointer<vtkRenderWindow> renderWindow;
    int X1, X2, X3, X1X2X3;
    //Assigning Values , Allocating Memory
    X1 = 10;
    X2 = 10;
    X3 = 10;
    X1X2X3 = X1*X2*X3;
    imageData = vtkSmartPointer<vtkImageData>::New();
    imageData->SetDimensions(X1 + 1, X2 + 1, X3 + 1);
    imageData->AllocateScalars(VTK_INT, 1);
    volumeProperty = vtkSmartPointer<vtkVolumeProperty>::New();
    compositeOpacity = vtkSmartPointer<vtkPiecewiseFunction>::New();
    color = vtkSmartPointer<vtkColorTransferFunction>::New();
    volume = vtkSmartPointer<vtkVolume>::New();
    mapper = vtkSmartPointer<vtkSmartVolumeMapper>::New();
    actor = vtkSmartPointer<vtkActor>::New();
    renderer = vtkSmartPointer<vtkRenderer>::New();
    renderWindowInteractor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
    renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
    volumeProperty->ShadeOff();
    volumeProperty->SetInterpolationType(0);
    volumeProperty->SetColor(color);
    volumeProperty->SetScalarOpacity(compositeOpacity);
    imageData->AllocateScalars(VTK_INT, 1);
    renderWindow->AddRenderer(renderer);
    renderWindowInteractor->SetRenderWindow(renderWindow);
    renderer->SetBackground(0.5, 0.5, 0.5);
    renderWindow->SetSize(800, 800);
    mapper->SetBlendModeToComposite();
    imageData->UpdateCellGhostArrayCache();
    mapper->SetRequestedRenderModeToRayCast();
    mapper->SetInputData(imageData);
    volume->SetMapper(mapper);
    volume->SetProperty(volumeProperty);
    renderer->AddViewProp(volume);
    volumeProperty->ShadeOff();

    //I is supposed to store the 3D data which has to be shown as volume visualization. This 3D data is stored 
    //as a 1D array in which the order of iteration over 3 dimensions is x->y->z, this leads to the following 
    //3D to 1D index conversion farmula index1D =  i + X1*j + X1*X2*k   
    vector<int> I(X1X2X3,0); // No need to use int* I = new int[X1X2X3] //Vectors are good
    std::iota(&I[0], &I[0] + X1X2X3, 1); //Creating dummy data as 1,2,3...X1X2X3

    //Setting Voxel Data and Its Properties
    for (int k = 0; k < X3 + 1 ; k++)   
    {
        for (int j = 0; j < X2 + 1 ; j++)
        {
            for (int i = 0; i < X1 + 1 ; i++)
            {
                int* voxel = static_cast<int*>(imageData->GetScalarPointer(i, j, k));

                if (i==X1 || j== X2 || k==X3)
                {
                    //Assigning zeros to dummy voxels, these will not be displayed anyways
                    voxel[0] = 0;
                }

                else
                {
                    //copying data from I to imagedata voxel
                    voxel[0] = I[i + X1*j + X1*X2*k];
                }               
            }
        }
    }

    //Setting Up Display Properties
    for (int i = 1; i < X1X2X3; i++)
    {
        compositeOpacity->AddPoint(i, 1);
        color->AddRGBPoint(i, double(rand()) / RAND_MAX, double(rand()) / RAND_MAX, double(rand()) / RAND_MAX);
    }

    renderer->ResetCamera();
    renderWindow->Render();
    renderWindowInteractor->Start();
    getchar();
    return 0;
}

现在可以正确看到每个维度中的预期体素数（根据上面的代码为 10 个）

VTK 体积可视化问题

VTK Volume Visualization Issue

c++

visualization

image-processing

cellular-automata

vtk