OptiTrack Motion Capture in ROS – rigid bodies and 3D points

This is one of the older things I did, but did not have enough time to make it into a post. So: the aim is to get a working stream of data from OptiTrack system into ROS Kinetic. A small catch: get individual points as well as rigid bodies.

Ok, first of all – the access to the OptiTrack was courtesy of Poznan University of Technology, kudos to them.

All files mentioned here are available in git repository:

First, let us check what is available:

Motive 1.8.0 Final 64-bit
Prime 17W 15111,15107,15112,15110,15117,15121,14908,15105,15122,15106
Hardware Key


Camera Calibration
Point Cloud
Rigid Bodies
Single Camera Tracking
VRPN Streaming
Trackd Streaming
NatNet Streaming
M Camera
M Subsystem
M Application UI
Marker History
Marker Trajectories
Camera Calibration
Volume Accuracy Tool


VRPN test

My first option is to use VRPN to connect to it, so let me try building a Slackware VRPN package – the necessary set of modifications:

vrpn is being compiled with -DVRPN_GPL_SERVER=on

I added FindVRPN.cmake to vrpn_client_ros directory cmake/


I added in CMakeLists.txt a line with:


and made the package.

So now to dummy test the vrpn:
edit the config file:

mcedit /usr/etc/vrpn.cfg

uncomment line vrpn_Tracker_NULL:

vrpn_Tracker_NULL Tracker0 2 2.0

launch the server:
#1 console:


#2 console:

vrpn_print_devices Tracker0@

If everything is alright – let us proceed with ROS client.


Compile vrpn_client_ros: (I keep my ROS in /opt/ros/kinetic)
(you can be in home directory if you want, doesn’t matter)

source /opt/ros/kinetic/setup.bash
mkdir vrpn_test
cd vrpn_test
mkdir src
cd src
git clone https://github.com/ros-drivers/vrpn_client_ros
cd ..
catkin_make_isolated -DCMAKE_INSTALL_PREFIX=/opt/ros/kinetic -DLIB_SUFFIX="64" -DCMAKE_BUILD_TYPE=Release --install

Now an important announcement:
VRPN streams only rigid bodies
Not cool, right? But we will fix it waaaaay later on, in Python. Right now, let us start it:


Create a Rigid Body from a set of points.
Make sure there are no white spaces in the filename: e.g. RigidBody1.

VRPN in advanced options:

Broadcast VRPN Data: true

Now check if the tracker responds:

vrpn_print_devices RigidBody1@

aaaand start ROS package vrpn_client_ros:

#1 console:

source /opt/ros/kinetic/setup.bash
roslaunch vrpn_client_ros sample.launch server:=

#2 console:

source /opt/ros/kinetic/setup.bash
rostopic echo /vrpn_client_node/RigidBody1/pose

a happy stream should be visible.

(PLACEHOLDER FOR EXPLANATION – you don’t need it, but I do:

roslaunch vrpn_client_ros sample.launch server:=
roslaunch mavros px4.launch fcu_url:="udp://:14550@" gcs_url:="udp://@
rosrun topic_tools relay /vrpn_client_node/(tracker name)/pose /mavros/mocap/pose rosrun topic_tools relay /vrpn_client_node/(tracker name)/pose /mavros/mocap/pose

ok, done, in case I forget it or lose it again)

Back to our usual program – what else can we do?

Maybe… MOCAP?

The setup for this one is as generic as humanly possible:

source /opt/ros/kinetic/setup.bash
mkdir mocap
cd mocap
mkdir src
cd src
git clone https://github.com/ros-drivers/mocap_optitrack
cd ..

Yeah, no surprises there. Now launch it:
#1 console

roslaunch mocap_optitrack mocap.launch

#2 console

rostopic list
rostopic echo /Robot_1/pose

What’s the result?

  seq: 3438
    secs: 1519816203
    nsecs: 344498680
  frame_id: "world"
    x: -1.3609367609
    y: -1.55265676975
    z: 0.809030890465
    x: -0.0133089488372
    y: 0.00888985395432
    z: 0.605775594711
    w: -0.795474588871

No deal. Also, a note – the configuration file is static and written by hand:


after only pointing him to a right multicast, it started working BUT only for rigid bodies – there is no individual marker info.

Any other bright ideas?


Ok, so again, do the installation procedure for the package:


I did it by hand, so you know the drill:

catkin_make_isolated -D...

standard to /opt/ros/kinetic.
I got a couple of errors at the very start:
missing launch/ in share/optitrack/, ok, I did a copy from src
missing config/ – the same, make a copy
missing scripts/ – the same.

That’s not a good start. Ok, now a quick sketch to get the basic data:

import optirx as rx

dsock = rx.mkdatasock(ip_address='',multicast_address='', port=1511)
version = (2, 7, 0, 0)  # NatNet version to use
while True:
    data = dsock.recv(rx.MAX_PACKETSIZE)
    packet = rx.unpack(data, version=version)
    if type(packet) is rx.SenderData:
        version = packet.natnet_version
    print packet 

And the result:

FrameOfData(frameno=846853, sets={'RigidBody1': [(-1.4107482433319092, 0.809095025062561, 1.4977911710739136), ...  tracked_models_changed=False)

Those three dots in the middle are from me – originally it exceeded the line limit in KWrite.

Sometimes the short version is also enough, I needed the multicast options, but just in case:

import optirx as rx

dsock = rx.mkdatasock()
version = (2, 9, 0, 0)  # NatNet version to use
while True:
    data = dsock.recv(rx.MAX_PACKETSIZE)
    packet = rx.unpack(data, version=version)
    if type(packet) is rx.SenderData:
        version = packet.natnet_version
    print( packet )

Now, if you would like to store a single packet for later:

import pickle

f = open('store.pckl', 'wb')
pickle.dump(packet, f)

and to restore it:

f = open('store.pckl', 'rb')
packet = pickle.load(f)

… and in case you don’t have OptiTrack on hand and no pennies to buy one (like me):

And that’s it – the individual points are there, so we’re finished.

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