[ros-users] stereo image sync

[Asghari Oskoei, Mohammadreza]

Blaise, 

The output to both

rostopic hz /stereo/left/image_rect_color   (image_view_proc)
rostopic hz /stereo/left/image_raw          (image_raw)

in exposure 5, is something as below  

Rate: x.xxx
max: xxx min: xxx ....
no new message 
no new message
no new message 
no new message
Rate: x.xxx
max: xxx min: xxx ....
no new message 
no new message
no new message 
no new message

in exposure 0.5, is something as below  

Rate: x.xxx
max: xxx min: xxx ....
Rate: x.xxx
max: xxx min: xxx ....

1 PC run just roscore + 1 PC run just camera drivers and image_proc + 2 net prosilical cameras (640x480) + 1 desktop to run rostopics all connected through a network with two hubs is hardly to say limitation in hardware, 

Could it be a problem in configuration?  

Reza,
 




-----Original Message-----
From: ros-users-bounces at code.ros.org [mailto:ros-users-bounces at code.ros.org] On Behalf Of Blaise Gassend
Sent: 15 February 2011 17:40
To: User discussions
Subject: Re: [ros-users] stereo image sync

What do you mean that you get one message out of 5? Do you mean that
you see messages on the image_raw topic but not on the output of
stereo_image_proc, or does it mean that the images aren't even
arriving on the image_raw topic?

In any case, resource limitations of various types can cause a lower
than expected frame rate:
- CPU overload can cause frames to be dropped.
- Insufficient lighting can cause the exposure time to be long, and
the frame rate to be lower than requested.
- Insufficient network bandwidth can limit how many frames get over
the network (seems unlikely in your case).

Hard to say more without knowing more about your system.

On Tue, Feb 15, 2011 at 2:47 AM, Asghari Oskoei, Mohammadreza
<m.asghari-oskoei at herts.ac.uk> wrote:
>
>
> Hi,
>
> I setup a pair of prosilica camera, in mode 640x480 in two exposure rates 5
> and 0.5 ,
>
> When I subscribe to their topics by either "rostopic hz
> /stereo/left/image_rect_color" or "rostopic hz /stereo/left/image_raw"
>
>
>
> In exposure rate 0.5, receive all messages without missing any  and then it
> repeats again
>
> In exposure rate 5, receive just 1 message and miss other 4 messages then it
> repeats again
>
>
>
> I tried this in different rates and found out that I just can receive two
> messages (one left and one right) per second (or per ROS refresh rate), and
> any more messages would be missed by ROS.
>
>
>
> The other point is that when I run stereo_image_proc  it crashes as soon as
> starting to subscribe to it by either stereo_view or face_detector.
>
>
>
> Anyone can help, please?
>
> Reza,
>
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