PCL的NARF关键点提取代码

以下是使用PCL库进行NARF关键点提取的示例代码：

#include <iostream>
#include <pcl/io/pcd_io.h>
#include <pcl/features/narf_descriptor.h>

int main(int argc, char** argv)
{
    if(argc != 2)
    {
        std::cerr << "Usage: " << argv[0] << " cloud.pcd" << std::endl;
        return -1;
    }

    pcl::PointCloud<pcl::PointXYZ>::Ptr cloud(new pcl::PointCloud<pcl::PointXYZ>);
    pcl::io::loadPCDFile(argv[1], *cloud);

    pcl::PointCloud<pcl::Narf36>::Ptr narfs(new pcl::PointCloud<pcl::Narf36>);

    pcl::RangeImage range_image;
    pcl::RangeImage::CoordinateFrame coordinate_frame = pcl::RangeImage::CAMERA_FRAME;
    float angular_resolution = 0.5f;
    float support_size = 0.2f;
    Eigen::Affine3f scene_sensor_pose(Eigen::Affine3f::Identity());
    range_image.createFromPointCloud(*cloud, angular_resolution, pcl::deg2rad(360.0f), pcl::deg2rad(180.0f), scene_sensor_pose, coordinate_frame, support_size, support_size/2.0f);
    pcl::PointCloud<pcl::PointXYZ>::Ptr keypoints(new pcl::PointCloud<pcl::PointXYZ>);
    pcl::NarfKeypoint narf_keypoint_detector;
    narf_keypoint_detector.setRangeImage(&range_image);
    narf_keypoint_detector.getParameters().support_size = support_size;
    narf_keypoint_detector.compute(*keypoints);

    pcl::NarfDescriptor narf_descriptor(&range_image, &narf_keypoint_detector);
    narf_descriptor.getParameters().support_size = support_size;
    narf_descriptor.getParameters().rotation_invariant = true;
    narf_descriptor.compute(*narfs);

    boost::shared_ptr<pcl::visualization::PCLVisualizer> viewer(new pcl::visualization::PCLVisualizer("NARF Keypoints"));
    viewer->setBackgroundColor(0, 0, 0);
    viewer->addPointCloud<pcl::PointXYZ>(cloud, "cloud");
    viewer->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 1, "cloud");
    viewer->addPointCloud<pcl::PointXYZ>(keypoints, "keypoints");
    viewer->setPointCloudRenderingProperties(pcl::visualization::PCL_VISUALIZER_POINT_SIZE, 5, "keypoints");
    viewer->spin();

    return 0;
}

该代码加载点云数据后，使用 `pcl::RangeImage` 对其进行预处理，然后使用 `pcl::NarfKeypoint` 进行关键点提取，最终使用 `pcl::NarfDescriptor` 计算NARF描述符。提取出的关键点和原始点云数据一起显示在可视化窗口中。