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@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@willowgarage.com <mailto:konolige@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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