headtracker / mag lens / macro lens (linaccess at yokoy.de)

[linaccess at yokoy.de]

Hello Luke,

On Tue, 4 Sep 2007 16:11:34 -0700
"Luke Hutchison" <luke.hutch at gmail.com> wrote:

> Is the processing time for 640x480 the reason you're only using 90x30?
>

No, I am not at the point thinking about optimization the processing time.
You don't want to dance in front of the camera to control the mouse pointer. You just want to move your head a few degrees as if you would look to the edges of the display without moving your eyes. Then the area recognized from the camera is very small. It is like moving the mouse only one or two millimeters to move the mousepointer over the whole desktop. To get more 'delta pixel' I need a mag lens, I think.

regards,

yokoy


 
> You can actually dramatically increase the precision to which you can read
> back the bright point's location by fitting a paraboloid to the intensity
> values in the neighborhood of the brightest pixel, then reading off the
> location of the extremum of the paraboloid.  You will get at least one order
> of magnitude more accuracy that way than looking at the integer coords of
> the brightest pixel (perhaps as much as two orders of magnitude).
> 
> Luke
> 
> 
> On 9/4/07, linaccess at yokoy.de <linaccess at yokoy.de> wrote:
> >
> > Hello Mary Lou,
> >
> > On Tue, 04 Sep 2007 12:13:34 -0400
> > Mary Lou Jepsen <mljatolpc at gmail.com> wrote:
> >
> > > lenses are cheap.  it depends on what exactly you are doing with the
> > > software.
> >
> > tracking a little shiny point at the head and transform it into
> > mousepointer movements. Here is the description:
> > http://www.olpcaustria.org/mediawiki/index.php/Headtracker
> >
> > With the XO camera we typicaly use only 90x30 pixel from the 640x480
> > pixel. So I want to magnify the operative area with a lens.
> > Here is a picture of the area:
> >
> > http://www.olpcaustria.org/mediawiki/index.php/Headtracker#magnification_lens
> >
> >
> >
> > > American Science and Surplus is a good way to experiment:
> > > http://sciplus.com/category.cfm?subsection=21
> > >
> >
> > thank you for that link. A plastic lens is what I am searching for.
> >
> >
> > > then to china for mass production at very low price point.
> > >
> > >
> > > - Mary Lou
> > >
> > >
> >
> > regards,
> >
> > yokoy
> > --
> >
> > _______________________________________________
> > Devel mailing list
> > Devel at lists.laptop.org
> > http://lists.laptop.org/listinfo/devel
> >
> 


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