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Overview

This package provides interfaces and tools for bridging a running ROS system to the Point Cloud Library. These include ROS nodelets, nodes, and C++ interfaces.

ROS nodelets

pcl_ros includes several PCL filters packaged as ROS nodelets. These links provide details for using those interfaces:

• Extract_Indices

• PassThrough

• ProjectInliers

• RadiusOutlierRemoval

• StatisticalOutlierRemoval

• VoxelGrid

ROS C++ interface

pcl_ros extends the ROS C++ client library to support message passing with PCL native data types. Simply add the following include to your ROS node source code:

#include <pcl_ros/point_cloud.h>

This header allows you to publish and subscribe pcl::PointCloud<T> objects as ROS messages. These appear to ROS as sensor_msgs/PointCloud2 messages, offering seamless interoperability with non-PCL-using ROS nodes. For example, you may publish a pcl::PointCloud<T> in one of your nodes and visualize it in rviz using a Point Cloud2 display. It works by hooking into the roscpp serialization infrastructure.

The old format sensor_msgs/PointCloud is not supported in PCL.

Publishing point clouds

You may publish PCL point clouds using the standard ros::Publisher:

   1 #include <ros/ros.h>
   2 #include <pcl_ros/point_cloud.h>
   3 #include <pcl/point_types.h>
   4 #include <pcl_conversions/pcl_conversions.h>
   5 
   6 typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;
   7 
   8 int main(int argc, char** argv)
   9 {
  10   ros::init (argc, argv, "pub_pcl");
  11   ros::NodeHandle nh;
  12   ros::Publisher pub = nh.advertise<PointCloud> ("points2", 1);
  13 
  14   PointCloud::Ptr msg (new PointCloud);
  15   msg->header.frame_id = "some_tf_frame";
  16   msg->height = msg->width = 1;
  17   msg->points.push_back (pcl::PointXYZ(1.0, 2.0, 3.0));
  18 
  19   ros::Rate loop_rate(4);
  20   while (nh.ok())
  21   {
  22     pcl_conversions::toPCL(ros::Time::now(), msg->header.stamp);
  23     pub.publish (*msg);
  24     ros::spinOnce ();
  25     loop_rate.sleep ();
  26   }
  27 }

Subscribing to point clouds

You may likewise subscribe to PCL point clouds using the standard ros::Subscriber:

   1 #include <ros/ros.h>
   2 #include <pcl_ros/point_cloud.h>
   3 #include <pcl/point_types.h>
   4 #include <boost/foreach.hpp>
   5 
   6 typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;
   7 
   8 void callback(const PointCloud::ConstPtr& msg)
   9 {
  10   printf ("Cloud: width = %d, height = %d\n", msg->width, msg->height);
  11   BOOST_FOREACH (const pcl::PointXYZ& pt, msg->points)
  12     printf ("\t(%f, %f, %f)\n", pt.x, pt.y, pt.z);
  13 }
  14 
  15 int main(int argc, char** argv)
  16 {
  17   ros::init(argc, argv, "sub_pcl");
  18   ros::NodeHandle nh;
  19   ros::Subscriber sub = nh.subscribe<PointCloud>("points2", 1, callback);
  20   ros::spin();
  21 }

ROS nodes

Several tools run as ROS nodes. They convert ROS messages or bags to and from Point Cloud Data (PCD) file format.

bag_to_pcd

Usage

 $ rosrun pcl_ros bag_to_pcd <input_file.bag> <topic> <output_directory>

Where:

• <input_file.bag> is the bag file name to read.

• <topic> is the topic in the bag file containing messages to save.

• <output_directory> is the directory on disk in which to create PCD files from the point cloud messages.

Example

Read messages from the /laser_tilt_cloud topic in data.bag, saving a PCD file for each message into the ./pointclouds subdirectory.

 $ rosrun pcl_ros bag_to_pcd data.bag /laser_tilt_cloud ./pointclouds

convert_pcd_to_image

Published Topics

• A stream of images generated from the PCD file.

Usage

 $ rosrun pcl_ros convert_pcd_to_image <cloud.pcd>

Read the point cloud in <cloud.pcd> and publish it in ROS image messages at 5Hz.

convert_pointcloud_to_image

Subscribed Topics

• A stream of point clouds to convert to images.

Published Topics

• Corresponding stream of images.

Examples

Subscribe to the /my_cloud topic and republish each message on the /my_image topic.

 $ rosrun pcl_ros convert_pointcloud_to_image input:=/my_cloud output:=/my_image

To view the images created by the previous command, use image_view.

 $ rosrun image_view image_view image:=/my_image

pcd_to_pointcloud

Published Topics

• A stream of point clouds generated from the PCD file.

Parameters

• Transform frame ID for published data.

Usage

 $ rosrun pcl_ros pcd_to_pointcloud <file.pcd> [ <interval> ]

Where:

• <file.pcd> is the (required) file name to read.

• <interval> is the (optional) number of seconds to sleep between messages. If <interval> is zero or not specified the message is published once.

Examples

Publish the contents of point_cloud_file.pcd once in the /base_link frame of reference.

 $ rosrun pcl_ros pcd_to_pointcloud point_cloud_file.pcd

Publish the contents of cloud_file.pcd approximately ten times a second in the /odom frame of reference.

 $ rosrun pcl_ros pcd_to_pointcloud cloud_file.pcd 0.1 _frame_id:=/odom

pointcloud_to_pcd

Subscribed Topics

• A stream of point clouds to save as PCD files.

Parameters

• Prefix for PCD file names created.

• If set, the transform from the fixed frame to the frame of the point cloud is written to the VIEWPOINT entry of the pcd file.

• Output the pcd file in binary form.

• In case that binary output format is set, use binary compressed output.

Examples

Subscribe to the /velodyne/pointcloud2 topic and save each message in the current directory. File names look like 1285627014.833100319.pcd, the exact names depending on the message time stamps.

 $ rosrun pcl_ros pointcloud_to_pcd input:=/velodyne/pointcloud2

Set the prefix parameter in the current namespace, save messages to files with names like /tmp/pcd/vel_1285627015.132700443.pcd.

 $ rosrun pcl_ros pointcloud_to_pcd input:=/my_cloud _prefix:=/tmp/pcd/vel_

More examples

We have more examples on http://wiki.ros.org/pcl_ros/Tutorials page