-------- Original Message --------
Subject:        Re: Historical Topographic Maps
Date:   Sat, 12 Dec 2009 07:54:36 -0600
From:   Mike Flannigan <[log in to unmask]>
To:     Maps, Air Photo & GIS Forum <[log in to unmask]>
References:     <[log in to unmask]>




I'm sure glad this discussion came up.  I have
never understood why 7.5' topos are so freely
available and the 15' topos are so scarce in
electronic format.  Let's see - there are 1/4
as many 15' topos, they have been around longer,
they are more interesting from a historical
perspective, many people prefer them when
working in the field due to their smaller size,
and yet georeferenced 15' DRG's in electronic
format - less than 1% of USA coverage (that
I know of).

I think I'm hearing that we only have the
7.5' digital topos because the govt made a
concerted effort to do those.  I'm still confused
as to why they didn't do the 15' maps - I'm
guessing $ is the main reason.

I'm so glad to hear the 15' topos will be available
soon.  And I'm also glad to hear that many libraries
will be moving to large format scanners and printers.
This may really open up the field to the obscure maps
in your collections.

In the future I'm sure the whole thing will be vectorized,
and these raster scans will be ancient history.

Another thing that bothers me is the dearth of freely
available maps in other parts of the world.  I suspect
a day will come when these satellites will be used to
create some worldwide map products at a reasonable
resolution for free.  Maybe we'll have Bing maps for the
whole world soon.



Mike Flannigan


>
>Update from University of New Hampshire:
http://docs.unh.edu/nhtopos/nhtopos.htm
>We have all the 15' topos for New England and New York scanned as
quarter quads at 200 dpi.  Higher resolution 600 dpi, georeferenced 15'
New Hampshire quadrangles with collar information should be available
this spring (versions without collars are already available through our
partner, GRANIT, the NH GIS repository).  We would like to work with
USGS on 7.5' NH topos, but have not been able to make that happen.  We
have not rescanned the rest of New England/NY, but we have stitched the
quads and they should also be available in the spring.
>We also will be working on the interface and updating accompanying text.
>Thelma Thompson