-------- Original Message --------
Subject:        Large format capture systems
Date:   Tue, 09 May 2006 23:02:15 -0700
From:   Dr. Virginia R. Hetrick <[log in to unmask]>
To:     Maps, Air Photo & Geospatial Systems Forum <[log in to unmask]>



Hi, Jon -

You might take a look at the following two technologies:

1.  A device called a SmartBoard which uses its own nominally colored
"markers" that you could use to trace with.  Pretty expensive (around
$10,000 US for one as I recall).  Problem is that the spatial resolution
of the "markers" which operate by interrupting a grid of light beans is
pretty course.

2.  A better solution might be to use a large scale digitizing tablet,
say 1.5 meters or 2 meters square, which will normally have a
light-colored surface.  You should be able to mount it with the surface
in a vertical position with the projector system centered on the
digitizing tablet.

Some years ago I wound up digitizing the polygons of a classified,
projected, Landsat image after I had digitally rectified the image of
some Atlantic barrier islands to a map projection.  I found the real
problem was how to avoid getting my head (or other body parts) in the
way while tracing the projected image.   By the time I was done, I had
pretty well gotten the hang of it.  To make my life easier, I used a
cross-hair device to do the tracing because I could handle it without my
hand (or head) getting in the way.  I figured that, if the viewing angle
to the cross-hair was consistent, then all the digitized areas would be
pretty good.

HTH.

virginia
--

\ /     Virginia R. Hetrick, here in sunny California
0      Voicemail:  310.471.1766  Email:  [log in to unmask]
Oo     "There is always hope."
My fave:  http://www.washington.edu/cambots/camera1_l.gif