问无法从发布者和订阅方节点可视化Rviz (ROS)中的PointCloud

EN

ros::Subscriber subPointCloud;
ros::Publisher pubPointCloud;

void DEM(const sensor_msgs::PointCloud2ConstPtr& input)
{
  ROS_DEBUG("Point Cloud Received");
  pcl::PointCloud<pcl::PointXYZ>::Ptr cloud (new pcl::PointCloud<pcl::PointXYZ>);
  sensor_msgs::PointCloud2 output;

  // Convert from ROS message to PCL point cloud
  pcl::fromROSMsg(*input, *cloud);
  pcl::toROSMsg(*cloud, output);

  output.header.stamp = ros::Time::now();
  output.header.frame_id = "/baselink";
  pubPointCloud.publish(output);

  }


int main(int argc, char** argv)
{
  ROS_INFO("Starting LIDAR Node");
  ros::init(argc, argv, "kitti_lidar_node");
  ros::NodeHandle nh;

  subPointCloud = nh.subscribe<sensor_msgs::PointCloud2>("input", 1, DEM);
  pubPointCloud = nh.advertise<pcl::PointCloud<pcl::PointXYZ> > ("output", 1);

  ros::spin();

  return 0;
}