topo maps online...

Adrian Snyder said:

This message is in answer to question posted on 12/28/04 re getting topo
maps for GPS calibration. For some reason any reply I make to the
newsgroup goes into a black hole so thought I'd try a different approach.

Larry---

Try the following website. I googled it
http://www.topozone.com/

Thanks for the info. That was one of the first sites
I found, but it only gave rough data unless you went
for the $ version. I was able to narrow it down to
within 20' or so using Terraserver, and then the
president of Topozone, who saw my post, was kind enough
to look up my exact elevation. I now know it far more
accurately than I need. :-)

Quoted message said:

Let me know if you get this... reason--- my replies are not getting on the
newsgroup.. Can't email you directly---your address is not accepted by mail
administrator...

Did you remove the nospam?

Larry Coon
University of California

Larry Coon said:

Adrian Snyder said:

This message is in answer to question posted on 12/28/04 re getting topo
maps for GPS calibration. For some reason any reply I make to the
newsgroup goes into a black hole so thought I'd try a different approach.

Larry---

Try the following website. I googled it
http://www.topozone.com/

Thanks for the info. That was one of the first sites
I found, but it only gave rough data unless you went
for the $ version. I was able to narrow it down to
within 20' or so using Terraserver, and then the
president of Topozone, who saw my post, was kind enough
to look up my exact elevation. I now know it far more
accurately than I need. :-)

Not sure what level of accuracy you need. If you need better accuracy
than a topo map, you can search for National Geodetic Survey benchmarks
in your area:
http://www.ngs.noaa.gov/cgi-bin/datasheet.prl

These benchmarks are located on places like bridge abutments, public
buildings, or buried a foot underground in the middle of a field.
(There is a picture at the NGS site)
http://www.ngs.noaa.gov/cgi-bin/get_image.prl?PROCESSING=list&PID=AE8289

Ed McNierney said:

Just to clarify things a bit, the coordinates you get for free on
TopoZone are no more "rough" than those you get with subscription
services. Our TopoZone Pro service adds features like street address
lookup, which can help you pinpoint the location for which you're
trying to find coordinates, but the coordinates themselves are just as
precise and accurate in both cases.

Oops, poor choice of words on my part. As I wrote in
another post, the problem was not really an issue of the
map's resolution as much as pinpointing exactly where I
am on the map, based on topographic features only.

Quoted message said:

And I will remind you that the coordinates you got from TerraServer
were 1/4 mile away from where you wanted to be <g>.

Yeah, perfect example...I narrowed my location down to
the wrong spot!

Larry Coon
University of California