Re: [Calmap] TopoZone vs TerraServa?

From: Scott Phillips (sphillips@esrp.csustan.edu)
Date: Mon Sep 11 2006 - 11:32:16 PDT

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    Hi, If the difference is in the order of 50-200 meters (~0.001 degrees),
    I would suspect a difference in map datums* between the maps and the
    coordinates displayed (NAD27 or NAD83/WGS84). Most topographic maps are
    based on the older North American Datum of 1927 (NAD27).

    Regards, Scott
    Scott Phillips, CSUS/ESRP
    sphillips@esrp.csustan.edu

    *
    http://www.connect.net/jbanta/FAQ.html#q03
    http://www.colorado.edu/geography/gcraft/notes/datum/datum.html

    Linda P Newman wrote:
    > And Happy Monday morning, folks!
    >
    > I’m curious to your impression for determining lat/long using TopoZone
    > vs TerraServer.
    >
    > I was requested for coordinates of a point in NoWhere NV at county
    > borders [not a specific named point]. I tried TopoZone and TerraServer,
    > maneuvered around to the exact county boundary and read the coordinates
    > in D/M/S. Clearly (as I have the 7.5’ sheet in front of me), the
    > TopoZone coordinates were more accurate than TerraServer – which was a
    > surprise.
    >
    >
    >
    > Comments? Suggestions?
    >
    >
    >
    > Hope to see you in Flagstaff for WAML!
    >
    > Linda Newman
    >
    > UNR
    >

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