## repository: https://code.ros.org/svn/ros-pkg
<<PackageHeader(pcl_ros)>>
<<TOC(4)>>

== 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 [[http://www.ros.org/wiki/pcl_ros/Filters|PCL filters]] packaged as ROS nodelets. These links provide details for using those interfaces:

 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#Extract_Indices|Extract_Indices]]
 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#PassThrough|PassThrough]]
 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#ProjectInliers|ProjectInliers]]
 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#RadiusOutlierRemoval|RadiusOutlierRemoval]]
 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#StatisticalOutlierRemoval|StatisticalOutlierRemoval]]
 * [[http://www.ros.org/wiki/pcl_ros/Tutorials/filters#VoxelGrid|VoxelGrid]]

== ROS C++ interface ==
`pcl_ros` extends the ROS [[roscpp|C++ client library]] to support message passing with [[pcl|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 [[http://www.ros.org/doc/api/pcl/html/classpcl_1_1PointCloud.html|pcl::PointCloud<T>]] objects as ROS messages. These appear to ROS as <<MsgLink(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 [[rviz/DisplayTypes/PointCloud|Point Cloud2 display]]. It works by hooking into the [[roscpp/Overview/MessagesSerializationAndAdaptingTypes|roscpp serialization]] infrastructure.

The old format <<MsgLink(sensor_msgs/PointCloud)>> is not supported in PCL.

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

{{{#!cplusplus
#include <ros/ros.h>
#include <pcl_ros/point_cloud.h>
#include <pcl/point_types.h>
#include <pcl_conversions/pcl_conversions.h>

typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;

int main(int argc, char** argv)
{
  ros::init (argc, argv, "pub_pcl");
  ros::NodeHandle nh;
  ros::Publisher pub = nh.advertise<PointCloud> ("points2", 1);

  PointCloud::Ptr msg (new PointCloud);
  msg->header.frame_id = "some_tf_frame";
  msg->height = msg->width = 1;
  msg->points.push_back (pcl::PointXYZ(1.0, 2.0, 3.0));

  ros::Rate loop_rate(4);
  while (nh.ok())
  {
    pcl_conversions::toPCL(ros::Time::now(), msg->header.stamp);
    pub.publish (*msg);
    ros::spinOnce ();
    loop_rate.sleep ();
  }
}
}}}

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

{{{#!cplusplus
#include <ros/ros.h>
#include <pcl_ros/point_cloud.h>
#include <pcl/point_types.h>
#include <boost/foreach.hpp>

typedef pcl::PointCloud<pcl::PointXYZ> PointCloud;

void callback(const PointCloud::ConstPtr& msg)
{
  printf ("Cloud: width = %d, height = %d\n", msg->width, msg->height);
  BOOST_FOREACH (const pcl::PointXYZ& pt, msg->points)
    printf ("\t(%f, %f, %f)\n", pt.x, pt.y, pt.z);
}

int main(int argc, char** argv)
{
  ros::init(argc, argv, "sub_pcl");
  ros::NodeHandle nh;
  ros::Subscriber sub = nh.subscribe<PointCloud>("points2", 1, callback);
  ros::spin();
}
}}}

== ROS nodes ==

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


<<Anchor(bag_to_pcd)>>
{{{
#!clearsilver CS/NodeAPI
node.0 {
name=bag_to_pcd
desc=Reads a bag file, saving all ROS point cloud messages on a specified topic as PCD files.
}
}}}

==== 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
}}}

<<Anchor(convert_pcd_to_image)>>
{{{
#!clearsilver CS/NodeAPI
node.0 {
name=convert_pcd_to_image
desc=Loads a PCD file, publishing it as a ROS image message five times a second.
pub {
0.name=output
0.type=sensor_msgs/Image
0.desc=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.

<<Anchor(convert_pointcloud_to_image)>>
{{{
#!clearsilver CS/NodeAPI
node.0 {
name=convert_pointcloud_to_image
desc=Subscribes to a ROS point cloud topic and republishes image messages.
sub {
0.name=input
0.type=sensor_msgs/PointCloud2
0.desc=A stream of point clouds to convert to images.
}
pub {
0.name=output
0.type=sensor_msgs/Image
0.desc=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
}}}

<<Anchor(pcd_to_pointcloud)>>
{{{
#!clearsilver CS/NodeAPI
node.0 {
name=pcd_to_pointcloud
desc=Loads a PCD file, publishing it one or more times as a ROS point cloud message.
pub {
0.name=cloud_pcd
0.type=sensor_msgs/PointCloud2
0.desc=A stream of point clouds generated from the PCD file.
}
param {
0.name=~frame_id
0.type=str
0.default=/base_link
0.desc=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
}}}

<<Anchor(pointcloud_to_pcd)>>
{{{
#!clearsilver CS/NodeAPI
node.0 {
name=pointcloud_to_pcd
desc=Subscribes to a ROS topic and saves point cloud messages to PCD files. Each message is saved to a separate file, names are composed of an optional `prefix` parameter, the ROS time of the message, and the `.pcd` extension.
sub {
0.name=input
0.type=sensor_msgs/PointCloud2
0.desc=A stream of point clouds to save as PCD files.
}
param {
0.name=~prefix
0.type=str
0.desc=Prefix for PCD file names created.
1.name=~fixed_frame
1.type=str
1.desc=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.
2.name=~binary
2.type=bool
2.default=false
2.desc=Output the pcd file in binary form. 
3.name=~compressed
3.type=bool
3.default=false
3.desc=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

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