写一个使用VTK可视化云图的程序

非常感谢您的提问。以下是使用 VTK 可视化云图的程序示例：

#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkProperty.h>
#include <vtkCamera.h>

int main(int argc, char *argv[])
{
// 创建球体数据源
vtkSmartPointer<vtkSphereSource> sphereSource = vtkSmartPointer<vtkSphereSource>::New();
sphereSource->SetCenter(., ., .);
sphereSource->SetRadius(1.);
sphereSource->SetPhiResolution(30);
sphereSource->SetThetaResolution(30);

// 创建球体的 Mapper
vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputConnection(sphereSource->GetOutputPort());

// 创建球体的 Actor
vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
actor->GetProperty()->SetColor(1., ., .);
actor->GetProperty()->SetOpacity(.5);

// 创建渲染器和窗口
vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->AddRenderer(renderer);

// 将 Actor 添加到渲染器中
renderer->AddActor(actor);
renderer->SetBackground(., ., .);

// 设置相机位置和方向
vtkSmartPointer<vtkCamera> camera = vtkSmartPointer<vtkCamera>::New();
camera->SetPosition(., ., 5.);
camera->SetFocalPoint(., ., .);
renderer->SetActiveCamera(camera);

// 创建交互器并启动渲染
vtkSmartPointer<vtkRenderWindowInteractor> interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
interactor->SetRenderWindow(renderWindow);
renderWindow->Render();
interactor->Start();

return ;
}