[ros-users] Questions about VSLAM
Abe Bachrach
abachrach at gmail.com
Wed Nov 3 05:16:00 UTC 2010
Since they are not synchronized, it will probably be equivalent to just
connecting 2 standard webcams. (probably won't work)
For ~$400 you can get 2 pt-grey firefly MV cameras, and synchronizing them
shouldn't be that hard...
you can either:
1) Use a PIC or other digital signal source to trigger both cameras using
their external trigger capability
or
2) connect the GPIO pin on one of the cameras to the external-trigger pin on
BOTH. (this only requires a jumper "cable between" the two cameras)
-=Abe
On Mon, Nov 1, 2010 at 12:46 AM, Kurt Konolige <konolige at willowgarage.com>wrote:
> Anh, I'm not sure if it will work, since I haven't tried it.
>
> Cheers --Kurt
>
> On Thu, Oct 28, 2010 at 1:03 PM, Anh Nguyen <nguyenminhanh at gmail.com>
> wrote:
> > 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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