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Cellular forums Home > Archive > Garmin GPS > January 2008 > Can DEM2TOPO use USGS data from Seamless to show topo data below
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Can DEM2TOPO use USGS data from Seamless to show topo data below
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| Gerry Snyder 2008-01-16, 4:33 am |
| With help from this group I have succeeded in making some topo maps for
my Garmin Etrex, but now I have a problem.
I will be going on a birding trip in the Salton Sea area of California,
and wanted to generate a map. The process works, but there are no
contour lines below an elevation of 0, which is where the interesting
areas are.
DEM2TOPO (v 2.9) has a setting for Sea level threshold, but setting it
to a negative value does not extend the contours.
Anyone have a suggestion for anything else to try, either in getting the
data from Seamless or in running DEM2TOPO?
TIA,
Gerry
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| b_gom@hotmail.com 2008-01-17, 12:34 pm |
| On Jan 15, 11:20=A0pm, Gerry Snyder <mesmerizer...@gmail.com> wrote:
> With help from this group I have succeeded in making some topo maps for
> my Garmin Etrex, but now I have a problem.
>
> I will be going on a birding trip in the Salton Sea area of California,
> and wanted to generate a map. The process works, but there are no
> contour lines below an elevation of 0, which is where the interesting
> areas are.
>
> DEM2TOPO (v 2.9) has a setting for Sea level threshold, but setting it
> to a negative value does not extend the contours.
>
> Anyone have a suggestion for anything else to try, either in getting the
> data from Seamless or in running DEM2TOPO?
>
> TIA,
>
> Gerry
Gerry,
DEM2TOPO does not support negative elevations, since it wasn't
anticipated that people would be using their GPS underwater, or that
people would get lost in Death Valley! You could try adding a constant
offset to the DEM to make all elevations positive, run it through
DEM2TOPO, then subtract the offset off of the generated contours.
Brad
(Note that there is a feedback form on the webpage for software
specific questions..)
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