VTK 显示 pcl::PointCloud<pcl::PointXYZRGB>::Ptr 类型

要在 VTK 中显示 pcl::PointCloud<pcl::PointXYZRGB>::Ptr 类型的点云数据，需要先将其转换为 VTK 中的数据类型。可以使用 PCL 中的 vtkSmartPointer、vtkPolyData、vtkPoints、vtkUnsignedCharArray 等类来实现。以下是一个简单的示例代码：

#include <pcl/point_types.h>
#include <pcl/point_cloud.h>
#include <pcl/io/pcd_io.h>
#include <vtkSmartPointer.h>
#include <vtkPolyData.h>
#include <vtkPoints.h>
#include <vtkUnsignedCharArray.h>
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>

int main(int argc, char** argv) {
    // 读取点云数据
    pcl::PointCloud<pcl::PointXYZRGB>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZRGB>);
    pcl::io::loadPCDFile<pcl::PointXYZRGB>("cloud.pcd", *cloud);

    // 创建 VTK 点云数据
    vtkSmartPointer<vtkPoints> points = vtkSmartPointer<vtkPoints>::New();
    vtkSmartPointer<vtkUnsignedCharArray> colors = vtkSmartPointer<vtkUnsignedCharArray>::New();
    colors->SetNumberOfComponents(3);
    colors->SetName("Colors");
    for (size_t i = 0; i < cloud->size(); i++) {
        pcl::PointXYZRGB point = cloud->points[i];
        points->InsertNextPoint(point.x, point.y, point.z);
        colors->InsertNextTupleValue(point.rgb);
    }
    vtkSmartPointer<vtkPolyData> polydata = vtkSmartPointer<vtkPolyData>::New();
    polydata->SetPoints(points);
    polydata->GetPointData()->SetScalars(colors);

    // 创建 VTK 渲染对象
    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
    mapper->SetInputData(polydata);
    vtkSmartPointer<vtkActor> actor = vtkSmartPointer<vtkActor>::New();
    actor->SetMapper(mapper);
    vtkSmartPointer<vtkRenderer> renderer = vtkSmartPointer<vtkRenderer>::New();
    renderer->AddActor(actor);
    vtkSmartPointer<vtkRenderWindow> renderWindow = vtkSmartPointer<vtkRenderWindow>::New();
    renderWindow->AddRenderer(renderer);
    vtkSmartPointer<vtkRenderWindowInteractor> interactor = vtkSmartPointer<vtkRenderWindowInteractor>::New();
    interactor->SetRenderWindow(renderWindow);

    // 显示点云数据
    renderWindow->Render();
    interactor->Start();

    return 0;
}

代码中，首先读取点云数据，然后创建 VTK 点云数据，并将 PCL 点云数据转换为 VTK 点云数据。接着，创建 VTK 渲染对象，并将点云数据添加到渲染对象中。最后，显示点云数据。