[ros-users] Simple navigation with USB-WebCAM

[RobotNV]

Adam,

Do you know of any data on how fast the movement of camera/objects need to be compared to the speed of rolling shutter to influence results?

Aren't those shutters pretty fast? :)

On Sep 27,  2010, at 12:45 PM, Adam Leeper <aleeper at stanford.edu> wrote:

> Hi Christian-
> 
> A cheap, easy stereo webcam is available from Minoru. http://www.minoru3d.com/ 
> It is about $60 on Amazon. It has a 6cm baseline, which makes it useful for stereo range sensing in the range of about 30cm to a few meters.
> 
> Using the uvc_stereo package from umd-ros-pkg, it is straightforward to get the stereo image feed and camera info published on ROS, and then all the calibration and processing pipeline pieces work too.
> 
> The main disadvantage of these solutions, however, is that webcameras use a rolling shutter, which means your stereo data is only reliable when the camera and scene are static. Any motion, especially fast motion, will cause skew in the image, which causes unreliable variations in the computed distance to points. I'm not sure how this would affect your efforts to navigate... I've been using stereo webcam stuff for mostly static analysis.
> 
> 
> --Adam
> 
> 
> 
> 
> Adam Leeper
> Stanford University
> aleeper at stanford.edu
> 719.358.3804
> 
> 
> On Mon, Sep 27, 2010 at 12:16 PM, Christian Mock <christian.mock.chrimo at googlemail.com> wrote:
> Hello ROS-Community,
> 
> I'm a total beginner using the amazing ros-environment...
> In the past, I've coded a lot of routines at simple ARM-based systems (Lego NXT and ARM9 Linux) using C and Lua.
> 
> Last weekend I've made some tests with the brandnew rosnxt package and I had much fun with this Lego Gimick ... it works with ROS ! :-D
> 
> 
> Now, I'd like to start with a new platform (Ubuntu & ROS) and have some rookie questions to the community:
> 
> For me it seems that ROS needs expensive rangefinders... True ???
> Or is it possible to use cheap stereo USB-CAMs for basic navigation ?
> 
> Any suggestions how to use ROS without SICK or any other expensive lasers ?
> 
> 
> Thanks in advance
> 
> Cheers
> Christian
> 
> 
> -- 
> Chrimo Private Google Mail Account
> 
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