[ros-users] Sync problem with stereo_image_proc
Radu Bogdan Rusu
rusu at willowgarage.com
Fri May 21 16:20:42 UTC 2010
Dear Sacha,
Thanks for the uploading the data. I had a look at the bag file that you recorded, and as far as I can tell, it looks
like the camera_info is screwed up:
header:
seq: 2145
stamp: 2144000000000
frame_id: fixed_frame
height: 240
width: 320
roi:
x_offset: 100
y_offset: 0
height: 240
width: 320
D: [0.0, 0.0, 0.0, 0.0, 0.0]
K: [inf, 0.0, 159.5, 0.0, inf, 119.5, 0.0, 0.0, 1.0]
R: [1.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0]
P: [inf, 0.0, 159.5, 0.0, 0.0, inf, 119.5, 0.0, 0.0, 0.0, 1.0, 0.0]
Did you calibrate the cameras using the instructions on the wiki? Having inf values in K and P is bad :)
Cheers,
Radu.
On 05/21/2010 09:15 AM, Sacha Aury wrote:
> Dear Radu
>
> Thanks for your help. Since my connection at work is not really fast, I
> will send the bag on http://fly.yozora-irc.net/shadow tonight. You can
> already see my disparity map and both left / right images at this place.
>
> Cheers,
> Sacha
>
> Le vendredi 21 mai 2010 à 08:55 -0700, Radu Bogdan Rusu a écrit :
>> Dear Sacha,
>>
>> Can you assemble a bag file with the following topics? Please replace "mystereo" with the name of your stereo camera:
>> /mystereo/left/image_raw
>> /mystereo/left/camera_info
>> /mystereo/right/image_raw
>> /mystereo/right/camera_info
>>
>> and upload it somewhere where I can access it?
>>
>> In the meantime, can you make a screenshot of the disparity image? Just visualize it using image_view, and save it to a
>> jpg/png.
>>
>> Thanks,
>> Radu.
>>
>> On 05/21/2010 02:41 AM, Sacha Aury wrote:
>>> Dear Radu,
>>>
>>> Even if I understand that having some not valid disparity values is
>>> possible, I actually do not have any good ones. Moreover, all my points
>>> are quite the same (0.0, 0.0, nan) which is a bit strange I think. What
>>> could I do to fix this ? I already tried to change parameters with
>>> dynamic_reconfigure, but it did not change anything.
>>>
>>> Cheers,
>>> Sacha
>>>
>>> Le jeudi 20 mai 2010 à 10:45 -0700, Radu Bogdan Rusu a écrit :
>>>> Dear Sacha,
>>>>
>>>> What you're seeing makes sense. Though your disparity "looks good", I am sure you don't have valid disparity values at
>>>> each pixel in the disparity image. None of us do :). What you are seeing as the output of rostopic echo is the list of
>>>> 3D points that do not have valid disparity values (we mark those with nan).
>>>>
>>>> Cheers,
>>>> Radu.
>>>>
>>>> On 05/20/2010 09:37 AM, Sacha Aury wrote:
>>>>> I do not really understand why, but I looked to the TF tutorial, added a
>>>>> few things to my program and rviz do not complain anymore. To recap, I
>>>>> now have a disparity map, rviz do not complain about a fixed_frame, but
>>>>> my goal is to get the points cloud. Rviz warns :
>>>>> [ WARN] 1274372115.122808000: TF_OLD_DATA ignoring data from the past
>>>>> for frame /test at time 16566 according to authority /camera_sync
>>>>> Possible reasons are listed at
>>>>>
>>>>>
>>>>>
>>>>> $rostopic echo /stereo/points | less :
>>>>> header:
>>>>> seq: 937
>>>>> stamp: 18596000000000
>>>>> frame_id: fixed_frame
>>>>> points: [
>>>>> x: 0.0
>>>>> y: 0.0
>>>>> z: nan,
>>>>> x: 0.0
>>>>> y: 0.0
>>>>> z: nan,
>>>>> x: 0.0
>>>>> y: 0.0
>>>>> z: nan,
>>>>> x: 0.0
>>>>> y: 0.0
>>>>> z: nan,
>>>>> x: 0.0
>>>>> y: 0.0
>>>>> z: nan,
>>>>> x: 0.0
>>>>>
>>>>> I don't get it, since my disparity map looks good. I can send you a
>>>>> screenshot of the map if you need it.
>>>>> So, why is the processing not sending the good coords ? I did not
>>>>> calibrate my cameras since I did not find a way to do it for stereo
>>>>> vision, is there a problem with that ?
>>>>>
>>>>> Thanks.
>>>>>
>>>>> Le mercredi 19 mai 2010 à 10:38 -0700, Josh Faust a écrit :
>>>>>> If you don't have a TF transform tree (http://ros.org/wiki/tf), the
>>>>>> fixed frame needs to match the frame you've set. You also need to set
>>>>>> the timestamp in the header.
>>>>>>
>>>>>> msg.header.stamp = ros::Time::now();
>>>>>>
>>>>>> Josh
>>>>>>
>>>>>> On Wed, May 19, 2010 at 7:53 AM, Sacha Aury<sacha at shadowrobot.com>
>>>>>> wrote:
>>>>>> Thanks for your help. I now have a single node synchronizing
>>>>>> my two
>>>>>> cameras (image and infos). It works with the stereo_view and I
>>>>>> get the
>>>>>> disparity map, which I am configuring. My question is now
>>>>>> about rviz,
>>>>>> which I've never used. It seems to need a fixed frame to
>>>>>> display my 3D
>>>>>> cloud points. I tried to set a frame_id in my synchronization
>>>>>> node
>>>>>> (before broadcasting it to stereo_image_proc), but it does not
>>>>>> work,
>>>>>> rviz still can't get any fixed frame.
>>>>>>
>>>>>> How can I do that ? I think I am close to the result, but I
>>>>>> can't see
>>>>>> it !
>>>>>>
>>>>>> Le mardi 18 mai 2010 à 09:07 -0700, Blaise Gassend a écrit :
>>>>>>
>>>>>> > Hi Sacha,
>>>>>> >
>>>>>> > stereo_image_proc doesn't care about when your message was
>>>>>> published, it
>>>>>> > just cares about the timestamp in the message. So your
>>>>>> republishing node
>>>>>> > needs to set the timestamp, both in the image topic and in
>>>>>> the
>>>>>> > camera_info topic.
>>>>>> >
>>>>>> > Blaise
>>>>>> >
>>>>>> > On Tue, 2010-05-18 at 16:29 +0100, Sacha Aury wrote:
>>>>>> > > I think that having a hardware solution is a bit overkill
>>>>>> for my
>>>>>> > > problem. So I tried to write a node which collected image
>>>>>> messages from
>>>>>> > > my two cameras and which published both message every x
>>>>>> seconds,
>>>>>> > > typically 1/2. And when I am using
>>>>>> image_pipeline/stereo_image_proc, I
>>>>>> > > got messages of that kind :
>>>>>> > >
>>>>>> > > [ WARN] 1274196325.866264000: [stereo_image_proc] Low
>>>>>> number of
>>>>>> > > synchronized left/right image pairs received.
>>>>>> > > Left images received: 831
>>>>>> > > Right images received: 831
>>>>>> > > Synchronized pairs: 0
>>>>>> > > Possible issues:
>>>>>> > > * The cameras are not synchronized.
>>>>>> > > * The network is too slow. For each synchronized image
>>>>>> pair, at most 1
>>>>>> > > is getting through.
>>>>>> > >
>>>>>> > > I don't know what I could do more, since the
>>>>>> synchronisation should be
>>>>>> > > done by a TimeSynchronizer in the stereo_image_proc class.
>>>>>> Could it be
>>>>>> > > posible to cheat on the timestamps in any way ?
>>>>>> > >
>>>>>> > > Thanks, and sorry for the double post, I made a mistake at
>>>>>> first.
>>>>>> > >
>>>>>> > > Le lundi 17 mai 2010 à 07:53 -0700, Gary Bradski a écrit :
>>>>>> > > > What level do you want synchronization on? Within
>>>>>> framerate (both
>>>>>> > > > frames happen randomly but within 1/30 of a second of
>>>>>> each other) or
>>>>>> > > > exact frame synchronization? The first is achievable,
>>>>>> the second needs
>>>>>> > > > extra hardware.
>>>>>> > > >
>>>>>> > > > At most, ROS can get you timestamps to align to, but to
>>>>>> get actual
>>>>>> > > > simultaneous frames, you'll need a triggering signal in
>>>>>> hardware such
>>>>>> > > > as a wire between 2 cameras (that allow for this). Some
>>>>>> 1394 cameras
>>>>>> > > > may allow triggering over the 1394 bus and then you'll
>>>>>> only have the
>>>>>> > > > problem of getting both buses to trigger at the same
>>>>>> time ... which
>>>>>> > > > may be approximately possible, most of the time ... on
>>>>>> average.
>>>>>> > > > Depends on the driver and the 1394 port.
>>>>>> > > >
>>>>>> > > > I've seen an automotive 1394 article (not ROS related)
>>>>>> where they have
>>>>>> > > > about 10 cameras. The cameras run the cameras at very
>>>>>> high framerates
>>>>>> > > > and then they do timestamp synchronization which allows
>>>>>> fairly
>>>>>> > > > synchronous alignment of multiple with no extra
>>>>>> hardware.
>>>>>> > > >
>>>>>> > > > Gary
>>>>>> > > >
>>>>>> > > > On Mon, May 17, 2010 at 5:23 AM, Sacha Aury
>>>>>> <sacha at shadowrobot.com>
>>>>>> > > > wrote:
>>>>>> > > > Hi,
>>>>>> > > >
>>>>>> > > > I am trying to make a stereo camera acquisition
>>>>>> using ROS with
>>>>>> > > > the
>>>>>> > > > cameradc1394 driver and the stereo_proc package.
>>>>>> I've got a
>>>>>> > > > separate
>>>>>> > > > computer to stream the image_raw from my two
>>>>>> cameras. The
>>>>>> > > > stream works,
>>>>>> > > > but when I launch stereo_image_proc, it seems
>>>>>> that my two
>>>>>> > > > cameras are
>>>>>> > > > not synchronized :
>>>>>> > > >
>>>>>> > > > [ WARN] 1274098675.074074000:
>>>>>> [stereo_image_proc] Low number
>>>>>> > > > of
>>>>>> > > > synchronized left/right image pairs received.
>>>>>> > > > Left images received: 3079
>>>>>> > > > Right images received: 3076
>>>>>> > > > Synchronized pairs: 0
>>>>>> > > > Possible issues:
>>>>>> > > > * The cameras are not synchronized.
>>>>>> > > > * The network is too slow. For each
>>>>>> synchronized image
>>>>>> > > > pair, at most 1
>>>>>> > > > is getting through.
>>>>>> > > >
>>>>>> > > > Here is my launch file :
>>>>>> > > >
>>>>>> > > > <!-- startstream.launch -->
>>>>>> > > > <launch>
>>>>>> > > > <param name="display" type="int"
>>>>>> value="0"/>
>>>>>> > > > <param name="framerate" type="double"
>>>>>> value="15"/>
>>>>>> > > > <param name="mode"
>>>>>> value="MODE_320x240_YUV422"/>
>>>>>> > > >
>>>>>> > > > <node name="camera_left" pkg="cameradc1394"
>>>>>> > > > type="cameradc1394"
>>>>>> > > > respawn="true">
>>>>>> > > > <param name="prefix" type="string"
>>>>>> > > > value="/stereo/left/"/>
>>>>>> > > > <param name="cameraindex" type="int"
>>>>>> value="0"/>
>>>>>> > > > </node>
>>>>>> > > >
>>>>>> > > >
>>>>>> > > > <node name="camera_right" pkg="cameradc1394"
>>>>>> > > > type="cameradc1394"
>>>>>> > > > respawn="true">
>>>>>> > > > <param name="prefix" type="string"
>>>>>> > > > value="/stereo/right/"/>
>>>>>> > > > <param name="cameraindex" type="int"
>>>>>> value="1"/>
>>>>>> > > > </node>
>>>>>> > > >
>>>>>> > > > </launch>
>>>>>> > > >
>>>>>> > > > Is there any specific way to make the two
>>>>>> cameras
>>>>>> > > > synchronize ?
>>>>>> > > >
>>>>>> > > > I am following that tutorial :
>>>>>> > > >
>>>>>> > > > http://www.ros.org/wiki/stereo_image_proc
>>>>>> > > >
>>>>>> > > > Thank you for any help.
>>>>>> > > >
>>>>>> > > > Sacha
>>>>>> > > >
>>>>>> > > >
>>>>>> > > > _______________________________________________
>>>>>> > > > ros-users mailing list
>>>>>> > > > ros-users at code.ros.org
>>>>>> > > > https://code.ros.org/mailman/listinfo/ros-users
>>>>>> > > >
>>>>>> > > > _______________________________________________
>>>>>> > > > ros-users mailing list
>>>>>> > > > ros-users at code.ros.org
>>>>>> > > > https://code.ros.org/mailman/listinfo/ros-users
>>>>>> > >
>>>>>> > >
>>>>>> > > _______________________________________________
>>>>>> > > ros-users mailing list
>>>>>> > > ros-users at code.ros.org
>>>>>> > > https://code.ros.org/mailman/listinfo/ros-users
>>>>>> >
>>>>>> >
>>>>>> > _______________________________________________
>>>>>> > ros-users mailing list
>>>>>> > ros-users at code.ros.org
>>>>>> > https://code.ros.org/mailman/listinfo/ros-users
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> ros-users mailing list
>>>>>> ros-users at code.ros.org
>>>>>> https://code.ros.org/mailman/listinfo/ros-users
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> ros-users mailing list
>>>>>> ros-users at code.ros.org
>>>>>> https://code.ros.org/mailman/listinfo/ros-users
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> ros-users mailing list
>>>>> ros-users at code.ros.org
>>>>> https://code.ros.org/mailman/listinfo/ros-users
>>>>
>>>
>>>
>>
>
>
--
| Radu Bogdan Rusu | http://rbrusu.com/
More information about the ros-users
mailing list