This is an index of county-based mosaics of USGS topographic maps.
Map images were derived from scans of USGS 7.5 minute quadrangle maps
(Digital Raster Graphics) circa 2000, from which the map collar
information was removed. Images are GeoTIFF files in NAD83, UTM zone 18.
Purpose
A DRG is useful as a source or background layer in a GIS, as a
means to perform quality assurance on other digital products, and as a
source for the collection and revision of DLG data.
Supplemental Information
1. Checking a sample of the DRGs produced by the U.S.G.S.
indicated that the images were mis-registered by as much as 5 pixels
(about 12 meters). Although the images were re-registered in an effort
to reduce this error, perfect registration was not always possible. We
found that some of the original images were scanned with distortion that
could not be removed in the re-registration process. Thus, an unknown
proportion of the images have errors which, when combined with any
errors in the original maps, may exceed the limits of the National Map
Accuracy Standards adhered to by the original maps. If a scanned image
is to be used where accuracy at the 1:24,000 scale is needed, its
registration accuracy should be verified. 2. The maps upon which the
images are based used either metric contours in meters or English
contours in feet. There is no easy way to determine which units are used
for a particular image because the map collar information is not
present. Users need to be aware of the need to use care in determining
elevation units from these images. 3. For more background on Digital
Raster Graphics, refer to the USGS.
Temporal Extent
Currentness Reference
Ground Condition
Time Period
Beginning
1942
End
2000
Bounding Box
West
-79.762152
East
-71.856214
North
45.01585
South
40.496103
Theme Keyword
Digital Raster Graphic
basemaps
topographic maps
topo maps
index map
Theme Keyword Thesaurus
None
ISO Topic Category
imageryBaseMapsEarthCover
Theme Keyword
basemaps
index map
Theme Keyword Thesaurus
CUGIR Category
Place Keyword
New York State
Place Keyword Thesaurus
None
Temporal Keyword
Access Restrictions
None
Use Restrictions
Acknowledgement of the USGS would be appreciated in products
derived from these data.
Status
Complete
Maintenance and Update Frequency
Irregular
Point of Contact
Contact Organization
New York State Department of Environmental Conservation
Delivery Point
625 Broadway
City
Albany
State
NY
Postal Code
12233-4754
Country
USA
Contact Telephone
518-402-8940
Contact Electronic Mail Address
kfbarnes@gw.dec.state.ny.us
Data Quality Information
Logical Consistency Report
Not Applicable
Completeness Report
The DRG is a faithfully reproduced digital images of the original
source map. Some differences may be detected between the source graphic
used and the DRG due to the RGB values assigned that particular color. The
intent is to recreate those colors as near as possible. Data completeness
for DRG files reflect content of the source graphic. Features may have
been eliminated or generalized on the source graphic due to scale and
legibility constraints. For information on collection and inclusion
criteria, see U.S. Geological Survey, 1994, 24,000-Scale Digital Line
Graphs and Natioal Mapping Program Technical Instructions and U.S.
Geological Survey, 1994, Standards National Mapping Program Technical
Instructions.
