Topographic contours for Puerto Rico quadrangles converted form USGS Digital Line Graph data

Same as source DLG

Line features representing topographic contours. Digital vector format DLG-3

This data set was generated by converting USGS Digital Line Graph topographic data for the 1:20,000 Puerto Real quadrangle of Puerto Rico to the ESRI coverage format. The resulting coverage was projected from the original Universe Transverse Mercator (UTM) projection to the State Plane coordinate system for Puerto Rico (Lambert Conformal Conic projection). The elevation of the contour was assigned to ELVMTS (AAT item) to facilitate using the attributes. The vector GIS software  attributes. The vector GIS software Arc/Info (by ESRI) was used to process the files. The coverage was converted to the ESRI shapefile format

The source Digital Line Graph was digitized from the USGS quadrangle, by either the National Mapping Division, one of their cooperators, or one of their contractors. The digital data were produced by one of the following methods:

- scanning a stable-based copy of the graphic
materials. The scanning process captured the digital
data at a scanning resolution of at least 0.001 inches;
the resulting raster data were vectorized and then
attributed on an interactive editing station.

- scanning the paper map. The scanning process captured
the digital data at a scanning resolution of at least
0.001 inches; the resulting raster data were vectorized
and then attributed on an interactive editing station.

- scanning a stable-based copy of the graphic
materials. The resulting raster data were then manually
digitized and attributed on an interactive editing
station. The resolution of the digital data is at least
0.001 inches.

- scanning the paper map. The resulting raster data
were then manually digitized and attributed on an
interactive editing station. The resolution of the
digital data is at least 0.001 inches.

- manually digitizing from a stable-based copy of the
graphic material using a digitizing table to capture
the digital data at a resolution of at least 0.001
inches; attribution was performed either as the data
were digitized, or on an interactive edit station after
the digitizing was completed.

- manually digitizing from the paper map using a
digitizing table to capture the digital data at a
performed either as the data were digitized, or on an
interactive edit station after the digitizing was
completed.

The determination of the DLG production method was
based on various criteria, including feature density,
feature symbology, and availability of production
systems. Four control points corresponding to the four
corners of the quadrangle were used for registration
during data collection. An eight parameter projective
transformation was performed on the coordinates used in
the data collection and editing systems to register the
digital data to the internal coordinates used in
PROSYS, and a four parameter linear transformation was
performed from the PROSYS internal coordinates to
Universal Transverse Mercator (UTM) grid coordinates.
The DLG data were checked for position by one or more
of the following processes: - comparing plots of the
digital data to the graphic source. - comparing the
digital data to the digital raster scan.

DLG data classification was checked by at least one of
the following processes. - comparing plots of the
digital data to the graphic source - comparing the
digital data to the digital raster scan.

Line features between adjacent quadrangles were edgematched by the USGS Caribbean District

First draft of metadata created by msant@usgs.gov using
FGDCMETA.AML ver. 1.35 08/02/2000 on ArcInfo data set
m:\pr-data\qd-data\dlg\topo\prtp02

Dataset copied.

Internal feature number.

ESRI

Feature geometry.

ESRI

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