README

USGS Open-File Report 2004-1321

Topogrid Derived 10 meter Resolution Digital Elevation Model of the
Shenandoah National Park and Surrounding Region, Virginia

By

Peter G. Chirico and Seth D. Tanner

Explanation

The purpose of developing a new 10m resolution DEM of the Shenandoah
National Park Region was to more accurately depict geologic structure,
surfical geology, and landforms of the Shenandoah National Park Region
in preparation for automated landform classification. Previously, only a
30m resolution DEM was available through the National Elevation Dataset
(NED). During production of the Shenandoah10m DEM of the Park the
Geography Discipline of the USGS completed a revised 10m DEM to be
included into the NED. However, different methodologies were used to
produce the two similar DEMs. The ANUDEM algorithm was used to develop
the Shenadoah DEM data. This algorithm allows for the inclusion of
contours, streams, rivers, lake and water body polygons as well as spot
height data to control the elevation model. A statistical analysis using
over 800 National Geodetic Survey (NGS) first and second order vertical
control points reveals that the Shenandoah10m DEM, produced as a part of
the Appalachian Blue Ridge Landscape project, has a vertical accuracy of
±4.87 meters. The metadata for the 10m NED data reports a vertical
accuracy of ±7m. A table listing the NGS control points, the elevation
comparison, and the RMSE for the Shenandoah10m DEM is provided.

The process of automated terrain classification involves developing
statistical signatures from the DEM for each type of surficial deposit
and landform type. The signature will be a measure of several
characteristics derived from the elevation data including slope, aspect,
planform curvature, and profile curvature. The quality of the DEM is of
critical importance when extracting terrain signatures. The highest
possible horizontal and vertical accuracy is required. The more accurate
Shenandoah 10m DEM can now be analyzed and integrated with the geologic
observations to yield statistical correlations between the two in the
development of landform and surface geology mapping projects.

Contents of DVD

Quad_24k

Quad_bndry24k.e00- ArcInfo export format (.e00) file of the 1:24,000
scale USGS quadrangle boundaries of the study area.

DEM_data

snp_navd88_m.html -- FGDC compliant metadata file describing the 10m
DEM.

snp_navd88_m.dem -- 10m elevation data stored in USGS DEM format

snp_navd88_m.e00 -- 10m elevation data stored in ArcInfo export format
(.e00)

Plotfile

shenandoah.pdf -- Map plot of color shaded relief 10m DEM stored in
Adobe Acrobat .pdf file format.

shenandoah_sr.pdf - Map plot of shaded relief 10m DEM stored in Adobe
Acrobat .pdf file format.

Elevation Accuracy Report Table

Snp_dem_rmse.xls -- Microsoft Excel spreadsheet containing elevation
comparison between NGS vertical control points and Shenandoah 10m DEM
data.

Disclaimer

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employees, contractors, or subcontractors, make any warranty, express or
implied, nor assume any legal liability or responsibility for the
accuracy, completeness, or usefulness of any information, apparatus,
product, or process disclosed, nor represent that its use would not
infringe on privately owned rights.

References to non-USGS products, services and tradenames are provided
for information only and do not constitute endorsement or warranty,
express or implied, by the USGS, USDOI, or U.S. Government, as to their
suitability, content, usefulness, functioning, completeness, or
accuracy.