US GeoData Product Descriptions and Fact Sheets
- DEM's are digital records of terrain elevations for ground positions
at regularly spaced horizontal intervals (10-meter, 30-meter, and 2-arc
second).
- Level II DEM's are generated from digital contour line files
derived from USGS topogrophic quadrangles and are available in 7.5-minute,
15-minute, and 1-degree units.
DEM Fact Sheet
- DOQ's are digital images of aerial photographs in which displacements
caused by the camera and terrain have been removed. A DOQ combines the
image characteristics of a photograph with the geometric qualities of
a map.
- The standard DOQ produced by the USGS is a black-and-white or
color-infrared, 1-meter ground resolution, 3.75-minute image scanned from
1:40,000-scale quarter-quad centered photography produced under the National
Aerial Photography Program.
DOQ Fact Sheet
- DRG's are scanned images of USGS topographic quadrangles including
all map collar information. The image inside the map neatline is georeferenced
to the Earth's surface. DRG's can be used in combination with DOQ's
and elevation data to aid in the collection, review, and revision of other
types of digital data, especially vector data.
DRG Fact Sheet
- Vector representation in DLG-3 format of Public Land Survey System
(PLSS), boundary, hydrography, hypsography, and transportation features
as shown on USGS 7.5- and 15-minute topographic quadrangle maps. Please note
that the PLSS catagory is portrayed only as reference system and does not
contain information to the parcel level.
DLG Fact Sheet
Digital Line Graphs (DLG) -- Core Content
- Certain features, and some attribute information, found in full-content
DLG-3 data are not collected (refer to DLG-3 Core fact sheet for comparison).
- Due to the reduced feature content, less time is required to
generate a core-content DLG, and collection costs are correspondingly
reduced.
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