[ros-users] stereo image sync

[Asghari Oskoei, Mohammadreza]

Jack, Blaise,

Thank you, knowing this I'll check higher rates and then come back,
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: 16 February 2011 05:31
To: User discussions
Subject: Re: [ros-users] stereo image sync

Hi Asghari,

As Jack points out, I think that rostopic hz is giving you an update
once per second. If the exposure time is 5 seconds, then four out of
five updates of rostopic hz will not have any new messages.

Blaise

On Tue, Feb 15, 2011 at 12:45 PM, Asghari Oskoei, Mohammadreza
<m.asghari-oskoei at herts.ac.uk> wrote:
>
> 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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>> ros-users at code.ros.org
>> https://code.ros.org/mailman/listinfo/ros-users
>>
>>
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