<<PackageHeader(velodyne_driver)>>
<<TOC(4)>>

== Overview ==
This package provides basic device handling for Velodyne 3D LIDARs. For a list of all supported models refer to the [[#Supported Devices|Supported Devices]] section.

The driver publishes device-dependent [[http://docs.ros.org/indigo/api/velodyne_msgs/html/msg/VelodyneScan.html|velodyne_msgs/VelodyneScan]] data. The [[velodyne_pointcloud]] package provides nodes and nodelets to convert those data into more-convenient <<MsgLink(sensor_msgs/PointCloud2)>> messages.

The [[http://ros.org/wiki/velodyne/Reviews/2012-02-02_API_Review|API review]] describes the evolution of these interfaces.

=== Supported Devices ===
This driver supports all current Velodyne HDL-64E, HDL-32E, VLP-32C, and VLP-16 models. There is little difference in the way it handles those devices.

Different models publish packets at a different rate. Up through the ROS Groovy release, no distinction was made between the HDL-64E, HDL-64E S2, HDL-64E S2.1, and HDL-64E S3 variants. Unfortunately, the packet data rates for those devices are not all the same.

<<Version(Hydro)>>: the `model` parameter now expects an exact name: "VLP16", "32C", "32E", "64E", "64E_S2", "64E_S2.1", or "64E_S3", and generates the correct packet rates for them.<<BR>>
<<Version(1.3.0)>>: The VLP-16 ("Puck") model is now supported.<<BR>>
<<Version(1.5.0)>>: The VLP-32C ("Ultra Puck") model is now supported.<<BR>>
<<Version(1.5.2)>>: The HDL-64E S3 model is now supported.

== ROS Nodes ==
 * '''velodyne_node'''<<BR>>
 ROS node that captures Velodyne 3D LIDAR data and publishes it in raw form. This uses the same device driver class as [[#DriverNodelet|velodyne_driver/DriverNodelet]].
  * '''Publishes'''
   * ''velodyne_packets''<<BR>>
     type = velodyne_msgs/VelodyneScan<<BR>>
     Velodyne data packets (typically for one entire revolution of the device) in the `/velodyne` frame of reference.
   * ''diagnostics''<<BR>>
     type = diagnostic_msgs/DiagnosticStatus<<BR>>
     Diagnostic status information.

  * '''Parameters'''
   * ''frame_id''<<BR>>
     type = string<<BR>>
     default = velodyne<<BR>>
     Transform frame ID for the device (resolved using `tf_prefix`, if defined).
   * ''model''<<BR>>
     type = string<<BR>>
     default = "64E"<<BR>>
     Device model: "32E", "64E", "64E_S2" or "64E_S2.1", <<Version(1.3.0)>>: "VLP16", <<Version(1.5.0)>>: "32C", <<Version(1.5.2)>>: "64E_S3"
   * ''npackets''<<BR>>
     type = int<<BR>>
     default = enough for a complete revolution<<BR>>
     Number of packets to publish per message.
   * ''pcap''<<BR>
     type = string<<BR>>
     default = use real device (empty)<<BR>>
     PCAP dump input file name.
   * ''rpm''<<BR>>
     type = double<<BR>>
     default = 600<<BR>>
     Device rotation speed in Revolutions per Minute. '''Note:''' This does not modify the device configuration, it is just a value that the driver uses for calculating the packets per rotation.
   * ''port''<<BR>>
     type = int<<BR>>
     default = 2368<<BR>>
     <<Version(1.3.0)>>: UDP port to read.
   * ''device_ip''<<BR>>
     type = string<<BR>>
     default = use any device<<BR>>
     <<Version(1.3.0)>>: dotted decimal IP address of device.

==== Examples ====
Read the Velodyne HDL-64E (default) input socket as fast as possible. Publish each complete revolution to `velodyne_packets`.

{{{
$ rosrun velodyne_driver velodyne_node
}}}
Read the Velodyne Velodyne HDL-32E input socket as fast as possible. Publish each complete revolution to `velodyne_packets`.

{{{
 $ rosrun velodyne_driver velodyne_node _model:=32E
}}}
Read previously captured Velodyne packets from dump.pcap file. Publish messages to `velodyne_packets` at approximately 10 Hz rate. Dump files can be grabbed by `libpcap`, Velodyne's DSR software, `ethereal`, `wireshark`, `tcpdump`, or the [[#vdump|vdump]] command.

{{{
$ rosrun velodyne_driver velodyne_node _pcap:=dump.pcap
}}}
{{{
#!clearsilver CS/NodeAPI
node.0 {
 name = DriverNodelet
 desc = ROS nodelet that captures Velodyne 3D LIDAR data and publishes it in raw form. This uses the same device driver class as [[http://ros.org/wiki/velodyne_driver#velodyne_node|velodyne_node]]. All topics and parameters are identical.
}
}}}
== Utility Commands ==
<<Anchor(vdump)>>

=== vdump ===
The `vdump` command dumps raw data from the Velodyne LIDAR in PCAP format. It is a shell script wrapper providing some obscure options for the powerful `tcpdump` command.

Other methods of acquiring PCAP data include using `tcpdump` directly, `wireshark`, Velodyne's DSR software, and programming with `libpcap`.

==== Usage ====
{{{
  rosrun velodyne_driver vdump <file_prefix> [ <interface> ]

        <file_prefix>   file name to dump (with 3-digit number suffix)
        <interface>     interface to read from (default: "eth0")
}}}
==== Examples ====
Dump Velodyne packets from the `eth1` interface to a series of files named `pcap-000`, `pcap-001`, etc. Each file will be about 100MB. The time span that a single 100MB file covers depends on packet size and sampling rate of a particular model (for VLP-16 that is about 100 seconds worth of packets). Type `^C` when finished.

{{{
$ rosrun velodyne_driver vdump pcap- eth1
}}}
== Launch File Examples ==
Start a `velodyne_nodelet_manager` process running the driver nodelet. Other nodelets using the same nodelet manager process will have zero-copy access to the raw data messages the driver publishes.

{{{
 $ roslaunch velodyne_driver nodelet_manager.launch
}}}
Start a `velodyne_nodelet_manager` process for a Velodyne HDL-32E.

{{{
 $ roslaunch velodyne_driver nodelet_manager.launch model:=32E
}}}
Start a driver nodelet with input from `tcpdump.pcap`, in the current directory. The `pwd` provides a full path name, as required for `roslaunch`.

{{{
 $ roslaunch velodyne_driver nodelet_manager.launch pcap:=$(pwd)/tcpdump.pcap
}}}
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