[ros-users] Questions about VSLAM

[Anh Nguyen]

Sorry I forgot to reply all:

Thanks again Kurt,
>
> Do you know if this Minoru setup will work with vslam? I remember reading
> somewhere on ROS wiki that the timestamp from the two camera should be
> exactly the same, and it is said on the Minoru project website that those
> two webcams are not synchronized.
>
> Best,
>
> -M.A
>
>
>
> On Thu, Oct 28, 2010 at 2:07 PM, Kurt Konolige <konolige at willowgarage.com>wrote:
>
>> M.A., I remember this link for a stereo webcam:
>>
>> http://code.google.com/p/sentience/wiki/MinoruWebcam
>>
>> Reasonable baselines for indoors are 6 - 10 cm; wide-angle lenses also
>> help.
>>
>> Cheers --Kurt
>>
>>
>> On 10/28/2010 11:21 AM, Anh Nguyen wrote:
>>
>>> Hi Kurt,
>>>
>>> Thanks for the helpful answers. Look like cheap stereo vision is not an
>>> easy option, especially with my limited hardware skill.
>>>
>>> Can you extrapolate a bit more on augmenting VSLAM with odometry or
>>> IMUs. I have the odometry reading for my robot. How do I configure VSLAM
>>> to work with one camera and combine odometry / IMU with VSLAM (what
>>> would be a simple algorithm for that)?
>>>
>>>  From what I read, I also assume that IMU would work indoor, is that
>>> correct?
>>>
>>> Also, if I go with stereo camera,is there any requirement regarding the
>>> baseline, resolution, frame rate... for making it work with existing
>>> VSLAM stack?
>>>
>>> Best,
>>>
>>> -M.A
>>>
>>>
>>> On Thu, Oct 28, 2010 at 1:08 AM, Kurt Konolige
>>> <konolige at willowgarage.com <mailto:konolige at willowgarage.com>> wrote:
>>>
>>>    M.A. -
>>>
>>>    VSLAM currently works only with stereo cameras.  VSLAM with monocular
>>>    cameras is much less robust, unless it is augmented with other sensors
>>>    such as odometry or IMUs.
>>>
>>>    Using two webcams to make a stereo pair is difficult.  You have to:
>>>
>>>    1. Make sure they're rigidly mounted
>>>    2. Synchronize them
>>>
>>>    Synchronization is difficult for standard webcams.  At the moment I
>>>    don't think there are any cheap off-the-shelf stereo cams.  Here's one
>>>    reference for a do-it-yourself:
>>>
>>>    http://sszymczy.rootnode.net/index.php?menu=projects
>>>
>>>    It would be nice to do some kind of VSLAM on the Create using odometry
>>>    to help, but that would take some work.
>>>
>>>    Cheers --Kurt
>>>
>>>    On 10/27/2010 9:46 PM, Anh Nguyen wrote:
>>>     > Hi everyone,
>>>     >
>>>     > I have a few questions about VSLAM. I am new to robotics and most
>>>    of its
>>>     > terminologies so I would appreciate any references that may
>>>    explain the
>>>     > background needed to understand your answer :)
>>>     >
>>>     > - Can I use ROS VLSAM stack using only one camera (a webcam on my
>>>     > netbook to be more specific).
>>>     > - If so how do I configure VSLAM to get this to work?
>>>     > - If not, can I add another external webcam and use them as a
>>> stereo
>>>     > video system or do I have to purchase some commercial stereo
>>>    camera? If
>>>     > I have to purchase a commercial system, is there any  good one for
>>> <
>>>     > $400 range?
>>>     >
>>>     > Has anyone tried to get VSLAM to work with iRobot Create? I spent
>>> the
>>>     > last few weeks creating a reduced version of the PrairieDog stack
>>>    that
>>>     > work without the laser range finder and the stargazer, and mapped
>>> my
>>>     > office using the robot's bumper sensor, only to realize that I
>>> cannot
>>>     > rely solely on the robot's encoders for accurate localization.
>>>     >
>>>     > Thanks a lot,
>>>     >
>>>     > -M.A
>>>     >
>>>     >
>>>     >
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>>
>
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