<font size=2 face="Verdana">Dear ROCK devs,</font>
<br>
<br><font size=2 face="Verdana">I am at ESTEC/ESA and we are using ROCK
on our new robot named:"HDPR". We are close to the state that
we can go on the field to collect a dataset but, since I'm a fairly new
user/dev, I have a question: </font>
<br>
<br><font size=2 face="Verdana">I am using a custom build stereo camera,
with two firewire ptgrey connected on the same IEEE 1394 bus. So, using
the inherent 1394 properties, the two cameras are synchronised.</font>
<br><font size=2 face="Verdana">Now, software-wise I am using in a ruby
script the "</font><a href="http://rock-robotics.org/stable/pkg/drivers/orogen/camera_firewire/index.html"><font size=2 color=blue face="Verdana"><u>drivers/orogen/camera_firewire</u></font></a><font size=2 face="Verdana">"
component twice for the each camera and then the "</font><a href="http://rock-robotics.org/stable/pkg/perception/orogen/stereo/index.html"><font size=2 color=blue face="Verdana"><u>perception/orogen/stereo</u></font></a><font size=2 face="Verdana">"
to produce the disparity like this:</font>
<br>
<br><font size=2 face="Verdana">Ptgrey_camera_1->camera_firewire_orogen-----|-->stereo_orogen->disparity</font>
<br><font size=2 face="Verdana">
|</font>
<br><font size=2 face="Verdana">Ptgrey_camera_2->camera_firewire_orogen-----|</font>
<br>
<br><font size=2 face="Verdana">A struct view of the cameras in the rock-display
reveals that there is a timestamp from each camera like this:</font>
<br><font size=2 face="Verdana">Left PanCam:</font>
<br><font size=2 face="Verdana">Time: 28 Aug 2015 17:23:33.993947</font>
<br><font size=2 face="Verdana">Received time: 1 Jan 1970 01:00:00.0</font>
<br><font size=2 face="Verdana">Right PanCam:</font>
<br><font size=2 face="Verdana">Time: 28 Aug 2015 17:23:33.993943</font>
<br><font size=2 face="Verdana">Received time: 1 Jan 1970 01:00:00.0</font>
<br>
<br><font size=2 face="Verdana">I assume by now that "Time" means
sampled time and "Received time means" time saved to disk/ram!
Then we log the data in a .log file. In order to export the data to useful
.png files I use the following commands:</font>
<br><font size=2 face="Verdana">$ rock-export hdpr_perception.0.log --stream
/pancam_left.frame --filename "Pancam_#TIME_0.png"</font>
<br><font size=2 face="Verdana">$ rock-export hdpr_perception.0.log --stream
/pancam_right.frame --filename "Pancam_#TIME_2.png"</font>
<br>
<br><font size=2 face="Verdana"><u>Question one:</u></font>
<br><font size=2 face="Verdana">Even thought the images are actually synchronised
(I can see it from the product), the timestamps i am getting are not the
same because of the aforementioned struct properties. Is there an official
way of fixing this issue and have the images reported with exactly the
same timestamp, or should I create another component (or alter the stereo
one) in order to "fake" the timestamps to match? Something like
the</font><font size=3> </font><a href=http://wiki.ros.org/message_filters#Time_Synchronizer><font size=3 color=blue>ROS
time synchronzer</font></a><font size=3> would be perfect.</font>
<br>
<br><font size=2 face="Verdana"><u>Question two:</u></font>
<br><font size=2 face="Verdana">The fact is that we are using several sensors
on the rover (2 Stereo, IMU, TOF, DGPS) and in the best case we would like
to have them all synchronised (at some point since they've got different
frequencies) or at least real-time like, i.e. to know exactly when to expect
the images. Is there any "easy" (obviously, that is not easy)
way to do this in ROCK, since we cannot hardware trigger all of the sensors?</font>
<br>
<br><font size=2 face="Verdana">Thank you for your help and your time,</font>
<br><font size=2 face="Verdana">Evangelos Boukas</font>
<br><font size=1 color=#2f2f2f face="Verdana">=========================================================================</font>
<br>
<br><font size=1 color=#2f2f2f face="Verdana">Dip.Eng | M.Sc. in E.E.|Computer
Vision & Robotics Researcher | European Space Agency NPI</font>
<br><font size=1 color=#2f2f2f face="Verdana">Laboratory of Robotics and
Automation | School of Engineering | Democritus University of Thrace</font>
<br><font size=1 color=#2f2f2f face="Verdana">evanbouk@pme.duth.gr | </font><a href=http://robotics.pme.duth.gr/boukas><font size=1 color=blue face="Verdana">http://robotics.pme.duth.gr</font></a><font size=1 color=#2f2f2f face="Verdana">
| </font><a href=http://robotics.pme.duth.gr/boukas><font size=1 color=blue face="Verdana">http://robotics.pme.duth.gr/boukas</font></a><font size=1 color=#2f2f2f face="Verdana">
</font>
<br>
<br><font size=1 color=#2f2f2f face="Verdana">ESA - European Space Agency</font>
<br><font size=1 color=#2f2f2f face="Verdana">TEC-MMA - Automation and
Robotics Section </font>
<br>
<br>
<br><font size=1 color=#2f2f2f face="Verdana">ESTEC - European Space research
and TEchnology Centre</font>
<br><font size=1 color=#2f2f2f face="Verdana">Keplerlaan 1, PO Box 299 </font>
<br><font size=1 color=#2f2f2f face="Verdana">NL-2201 AZ Noordwijk, The
Netherlands </font>
<br><font size=1 color=#2f2f2f face="Verdana">Evangelos.Boukas@esa.int
| </font><a href=http://www.esa.int/TEC/Robotics/><font size=1 color=blue face="Verdana">http://www.esa.int/TEC/Robotics/</font></a>
<br><font size=1 color=#2f2f2f face="Verdana">Tel. +31 71 565 5499 </font>
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