10 Meter (1/3 Arc Second) USGS DEM 3D Terrain Data
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USGS Quad Sheet
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30 Meter DEM 3D Surface
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10 Meter DEM 3D Surface
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10 Meter DEM Contours
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The USGS 10 Meter DEM (Digital Elevation Model) data consists of a grid of elevation
values posted every 10 meters (actually, every 1/3 arc second). The USGS has released
this very accurate terrain data for a large portion of the US, especially in the
western states. We have found that contours produced from this data follow almost
exactly the original contours from the USGS paper 1:24,000 scale topo maps. 3D surfaces
from this new data contain much more detail than the older 30 meter data. Click
on the above 3d renderings to see the difference in detail.
We have been very careful to only offer those quadrangles
that have true 10 meter data. There are some areas where the USGS just resampled
the 30 meter data at 10 meters, offering no better accuracy. The 10 meter data in
TopoDepot is only from areas where the USGS actually digitized the elevation data
at 10 meter postings from the original quad sheets.
Click here to view a status map showing
where we have 10 meter data.
TopoDepot offers two ways of using this data:
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TopoDepot can create contour lines at any contour interval from this data. We recommend
however, that you use the same interval as the original USGS quadrangle since file
sizes can get very large at small contour intervals.
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TopoDepot can export an XYZ or NEZ surface file
for use in many 3D surface analysis programs including AutoDesk Civil 3D. An XYZ
file is an ASCII file consisting of all the DEM elevation points. Each point consists
of an X, and Y position in the desired map projection, and a Z value (elevation)
in either feet or meters. If you tile several quads together, then the XYZ file
is also tiled together. Topodepot also supports a variant of XYZ, called AutoDesk
Uploadable Format, or AUF.
TopoDepotOnDVD also provides the capability to
extract just a smaller portion of an XYZ file. This can be very useful since the
number of points within a single quad is quite large.
Note that the 10 Meter data has 9 times more points than
the 30 meter data. While this provides greater accuracy, it also increases file
sizes by approximately 9 times.
It is now possible to select the vertical datum
(NAVD88 or NGVD29) as well as the horizontal datum
and projection when you output the data.
For more information:
http://seamless.usgs.gov/website/seamless/products/3arc.asp
