#include <ros/ros.h>

#include <tf/transform_broadcaster.h>

int main(int argc, char** argv)

{

  ros::init(argc, argv, "robot_tf_publisher");

  ros::NodeHandle n;

  ros::Rate r();

  tf::TransformBroadcaster broadcaster;

  while(n.ok()){

//发布坐标变换

    broadcaster.sendTransform(tf::StampedTransform(tf::Transform(

                            tf::Quaternion(, , , ), //四元数

                            tf::Vector3(-0.25, 0.0, 0.0)),

                            ros::Time::now(),

                            "base_link",

                            "laser"));

    r.sleep();

  }

}

#include <ros/ros.h>

#include <geometry_msgs/PointStamped.h>

#include <tf/transform_listener.h>

//我们将创建一个函数，给定一个TransformListener，在“base_laser”坐标系中取一点，并将其转换为“base_link”坐标系。

// 这个函数将作为在我们程序的main()中创建的ros::Timer的回调，并且每秒都会触发。

void transformPoint(const tf::TransformListener& listener){

  //we'll create a point in the base_laser frame that we'd like to transform to the base_link frame

  geometry_msgs::PointStamped laser_point;

  laser_point.header.frame_id = "base_laser";

  //we'll just use the most recent transform available for our simple example

  laser_point.header.stamp = ros::Time();//时间戳

  //just an arbitrary point in space

  laser_point.point.x = 1.0;

  laser_point.point.y = 0.2;

  laser_point.point.z = 0.0;

  try{

    geometry_msgs::PointStamped base_point;

    listener.transformPoint("base_link", laser_point, base_point);//坐标中的点的位置变换

    ROS_INFO("base_laser: (%.2f, %.2f. %.2f) -----> base_link: (%.2f, %.2f, %.2f) at time %.2f",

        laser_point.point.x, laser_point.point.y, laser_point.point.z,

        base_point.point.x, base_point.point.y, base_point.point.z, base_point.header.stamp.toSec());

  }

  catch(tf::TransformException& ex){

    ROS_ERROR("Received an exception trying to transform a point from \"base_laser\" to \"base_link\": %s", ex.what());

  }

}

int main(int argc, char** argv){

  ros::init(argc, argv, "robot_tf_listener");

  ros::NodeHandle n;

//我们需要创建一个tf::TransformListener。一个TransformListener对象自动订阅了ROS变换消息主题和管理所有将在网络中广播的变换数据。

  tf::TransformListener listener(ros::Duration());

  //we'll transform a point once every second

  ros::Timer timer = n.createTimer(ros::Duration(1.0), boost::bind(&transformPoint, boost::ref(listener)));

  ros::spin();

}