[ros-users] Fwd: publishing large images at high fps using image_transport

[Dejan Pangercic]

Hi there,

I ran the program with the valgrind and found nothing fishy. Moreover
it turned out that the decay in publishing rate only happens when
there is a subscriber such as e.g. image_view subscribed to the topic.
What I then tried next was to subscribe to the output topic with 3
"rostopic hz /image_topic_2" commands only - see also an attached
rxgraph plot.
This resulted in every subscription having less and less publishing
rate (~ 30, 25 and 26 Hz respectively). Once again I ran this on one
machine and over the loopback. The program publishing images is now
also in tum-ros-pkg repo:
http://tum-ros-pkg.svn.sourceforge.net/viewvc/tum-ros-pkg/perception/image_algos/utils/openCV_to_ros.cpp?revision=432&view=markup
if someone wants to give it a try.

Could the decay in publishing rate be attributed to the way ROS's
subscribe mechanism handles the copying of data?

cheers, D.


On Fri, Apr 16, 2010 at 9:47 PM, Josh Faust <jfaust at willowgarage.com> wrote:
> Whoops, should've looked at the attached source.  In general a profiler is
> going to tell you what's taking time far better than we will.
>
> Josh
>
> On Fri, Apr 16, 2010 at 12:33 PM, Dejan Pangercic
> <dejan.pangercic at gmail.com> wrote:
>>
>> Hi Josh,
>>
>> I did not do profiling yet. However, since I read the image only once
>> when I start the program and then publish it from the memory, it can
>> not be harddrive.
>> D.
>>
>> On Fri, Apr 16, 2010 at 9:00 PM, Josh Faust <jfaust at willowgarage.com>
>> wrote:
>> > Have you tried profiling it to see where the time is being spent, and
>> > where
>> > the bottleneck is?  1.8MB * 30 = 54MB/sec, which could actually be
>> > harddrive-limited depending on the drive you're reading from.
>> >
>> > Josh
>> >
>> > On Fri, Apr 16, 2010 at 11:26 AM, Dejan Pangercic
>> > <dejan.pangercic at gmail.com> wrote:
>> >>
>> >> Hi there,
>> >>
>> >> I using an attached program to read an image from a disk and to then
>> >> continously publish it on an image topic at 30 fps. On _one_ machine
>> >> over loopback. When I tried it with a 1608x1236+0+0 color image
>> >> (1.8MB) and then used rostopic hz to display the publishing rate of
>> >> topic,
>> >> the most that I got was around 12, 13 Hz.
>> >> Any idea what would cause such a low performance? At what rates and
>> >> sizes do you folks usually send images around?
>> >>
>> >> thx and cheers, D.
>> >>
>> >> --
>> >> MSc. Dejan Pangercic
>> >> PhD Student/Researcher
>> >> Computer Science IX
>> >> Technische Universität München
>> >> Telephone: +49 (89) 289-17780
>> >> E-Mail: dejan.pangercic at in.tum.de
>> >> WWW: http://ias.cs.tum.edu/people/pangercic
>> >>
>> >> _______________________________________________
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>> >
>> >
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>>
>>
>>
>> --
>> MSc. Dejan Pangercic
>> PhD Student/Researcher
>> Computer Science IX
>> Technische Universität München
>> Telephone: +49 (89) 289-17780
>> E-Mail: dejan.pangercic at in.tum.de
>> WWW: http://ias.cs.tum.edu/people/pangercic
>> _______________________________________________
>> ros-users mailing list
>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>
>
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--
MSc. Dejan Pangercic
PhD Student/Researcher
Computer Science IX
Technische Universität München
Telephone: +49 (89) 289-17780
E-Mail: dejan.pangercic at in.tum.de
WWW: http://ias.cs.tum.edu/people/pangercic



-- 
MSc. Dejan Pangercic
PhD Student/Researcher
Computer Science IX
Technische Universität München
Telephone: +49 (89) 289-17780
E-Mail: dejan.pangercic at in.tum.de
WWW: http://ias.cs.tum.edu/people/pangercic
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