--- Begin Forwarded Message ---
Date: Tue, 01 Dec 1998 21:56:03 -0500
From: Mark Eaton <[log in to unmask]>
Subject: Re: Topographic Maps <fwd>
Sender: Mark Eaton <[log in to unmask]>
To: [log in to unmask], [log in to unmask],
[log in to unmask]
Reply-To: Mark Eaton <[log in to unmask]>
Message-ID: <[log in to unmask]>
I wouldn't put much faith in converting USGS DEM's into the exact contours that were used to generate the DEM's. We've been playing with the Grid->Contour algorithms for some time and our success has been far from outstanding. A lot of the problems have to do with the lack of consistency in terrain and as we all know the earths surface is anything but consistent. In regards to the availability of 24k DLG's, there is roughly 7% coverage for the entire US. We have 100% coverage for 100k DLG data for Hydro, Trans, PLSS & Bdys. If the Quads in question contain US Forest Service Lands you can acquire CFF files from the FS as an alternative. If your looking for 100% Topographic coverage that reflects the consistancy and content of the 24k Topographic Map your only option for quite some time will be the 24k Topographic Map. Sorry for the bad news.....mark
>>> Johnnie Sutherland <[log in to unmask]> 12/01 3:36 PM >>>
--- Begin Forwarded Message ---
Date: Tue, 01 Dec 1998 17:00:25 -0500
From: Tsering Wangyal Shawa <[log in to unmask]>
Subject: Re: Topographic Maps <fwd>
What sort of topographic information person needs. If a person need
elevation info s/he can download DEM data from usgs web
page(http://edcwww.cr.usgs.gov/doc/edchome/ndcdb/ndcdb.html). Of course,
all of the DEM 1:24,000 data are in sdts format. I hate this format(but
there are free translator which you can download from above web site).
Anyway, the sdts data can be converted into grid or ascii format then
person could bring them in ArcView Spatial Analyst or Arc/Info GRID Module.
You can either view them as DEM in a grid format or convert them into
contour lines. You could create similar contour interval as topo sheet to
get same contour line as USGS 1:24,000 Topo sheets.
Besides, DEM data-- there are DLG data where you get info about boundary,
hydrology, hypsography,
transportation etc. All of the above data are free.
Tsering Wangyal Shawa
Geographic Information Systems Librarian
Digital Map and Geospatial Information Center
Geosciences and Map Library
Guyot Hall
Princeton University
Princeton, NJ 08544
Tel: (609) 258-3247
Fax: (609) 258-1274
http://www.princeton.edu/~geolib/gis
>--- Begin Forwarded Message ---
>Date: Mon, 30 Nov 1998 13:32:02 -0600 (CST)
>From: Doralyn H Edwards <[log in to unmask]>
>Subject: Topographic Maps
>
>
>This may be a very naive question, but I'm not sure where else to go at
>this point. I have a patron who is looking for Topographic maps of the
>Crystal Crag, Bloody Mountain, and Mammoth Mountain regions in
>California at the 1:24,000 scale in a digital format. From my searching
>on the web, it doesn't appear that many topos are available on the web.
>Does anyone know of a place I can get this on the web for free--otherwise,
>we'll just scan them here (I'd rather not purchase them from a vendor,
>unless reasonably priced).
>
>Thanks--I'm new at this and I'm not sure where else to go with the
>question.
>
>Doralyn
>
>************************************************************
>Doralyn H. Edwards phone: (713)737-5691
>GIS/Data Librarian fax: (713)285-5902
>Fondren Library email: [log in to unmask]
>Rice University work: http://www.rice.edu/Fondren/GDC
>Houston, TX personal: http://is.rice.edu/~doralyn
>************************************************************
>
>
>
>
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>
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