# GRASS Help System

U.S. Geological Survey

## (USGS)

USGS: Elevation

Data Source:

National Cartographic Information Center
U.S. Geological Survey
User Services Section
507 National Center
Reston, VA 22092
Phone: 703-860-6045

Data Format:

Raster

Scale:

## 1:24000

Data Coverage:

Scattered quads throughout U.S. For current coverage write/call for
"Index to Digital Line Graph & Digital Elevation Model Data".

Data Description:

A regular array of elevation values referenced
to the UTM coordinate system with a spacing of
30 meters. Data are collected by either digitizing
7.5' contour overlays or scanning of photographs.
The data is available in one of three levels:
Level 1 - raw elevation data, only gross errors edited
Level 2 - data smoothed and edited to remove random errors
Level 3 - data edited and modified to ensure positional accuracy

Media:

Aquisition Costs:

$100/quad with a $25/tape service charge

Comments:

The NCIC/USGS also distributes digital elevation
data produced by the Defense Mapping Agency (DMA).
This data has a scale of 1:250000, is latitude/longitude
referenced, and a sampling interval of 3 arc seconds.
For more information see the Data Source Report for the
Defense Mapping Agency (DMA).

Information obtained from the USGS Circular 895-B
"Digital Elevation Models".

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Automatically created on: Thu Oct 13 02:16:43 2005