[ros-users] Questions about VSLAM

[Kurt Konolige]

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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