FLORIDA GEOGRAPHIC DATA LIBRARY DOCUMENTATION
VERSION 2003, RELEASED NOVEMBER, 2002.
USGS 1:24,000 HYDROGRAPHY - LINES
Geodataset Name: HY24L Geodataset Type: SHAPE Geodataset Feature: LINE
GENERAL DESCRIPTION:
This dataset contains Hydrological features from the USGS 1:24000 scale DLG's. This coverage is both a polygon and a line coverage.
DATA SOURCE(S): United States Geological Survey SCALE OF ORIGINAL SOURCE MAPS: 1:24,000 DATE OF AUTOMATION OR SOURCE: June 10, 1994 GEODATASET EXTENT: State of Florida
FEATURE ATTRIBUTE TABLES
Datafile Name: HY24L.DBF
NAME WIDTH TYPE PRECISION BANK 1 CHARACTER INTERMITT 1 CHARACTER DESCRIPT 100 CHARACTER FEATURE 20 CHARACTER
FEATURE ATTRIBUTE TABLES CODES AND VALUES:
BANK
INTERMITT Intermittent
Y Yes
DESCRIPT Descript Item
Description based upon ENT_LABEL
USER NOTES:
This coverage comes from the USGS USGeoData site as an SDTS Spatial Data Transfer Standard file. This was imported into ArcInfo Coverage format. It has been taken from its original single layer format with two themes (polygon and line) to two seperate layers one for polygons hy24p (lakes, ponds, etc.) and one for lines hy24l (streams, shoreline, etc)
This new coverage is different than past DLG's in that it does not rely on the Major Minor pairs to describe a feature. The new description item is called ENT_LABEL or Entity Label. This contains the familiar Major Minor Code (50 xxxx in this case), as one item (this is further simplified as the DESCRIPT item). This new coverage now parses out other descriptors into their own items:
INTERMITT is now an item that can be queried as 'Y' for those features that are intermittant.
SUBMERGED features can also be queried by reselecting for 'Y'
HOW TO USE THIS DATASET:
This dataset was automated at a scale of 1:24000. This means that
for every unit of measure on the map, say 1 inch, there are
24000 of those units (inches) on the ground. With this in mind
the map measures 1 inch for every 2000 feet of real distance.
Dataset was converted from a SDTS TOPOLOGICAL VECTOR PROFILE,
VERSION 1.0 JUNE 10, 1994. For documentation on this profile
please see FIPS 1731 PART 4. (This can be viewed in HTML format
on the internet, please go to the following address:
http://mcmcweb.er.usgs.gov/sdts/SDTS_standard_nov97/p4start.html)
According to the USGS:
As applied to the USGS 7.5minute quadrangle topographic map, the horizontal accuracy standard requires that the positions of 90 percent of all points tested must be accurate within 1/50th of an inch (0.05 centimeters) on the map. At 1:24,000 scale, 1/50th of an inch is 40 feet (12.2 meters). The vertical accuracy standard requires that the elevation of 90 percent of all points tested must be correct within half of the contour interval. On a map with a contour interval of 10 feet, the map must correctly show 90 percent of all points tested within 5 feet (1.5 meters) of the actual elevation.
This dataset should NOT be used for VERY Large scale (> 1:24000) analysis or site planning. This data is good for regional, state, or substate analysis only.
FGDL QUALITY ASSURANCE STATUS:
-Fuzzy tolerance temporarily increased to 3 meters for mapjoining
the 1044 7.5 minute quads that make up the state. No change was
detected following the mapjoin.
-DESCRIPT Item Added based upon ENT_LABEL item
-Set Tolerances to FGDL Standards
-Set Precision to Double
-Projected to FGDL Albers from UTM Zone 16 & 17
DATA LINEAGE SUMMARY:
LINEAGE DATA QUALITY REPORT for master data dictionary for USGS
DLG3 data. This data dictionary was created using the
following references: DLG3 to SDTS Attribute Mapping (NMD
1993); Standards for Digital Line Graphs, Part 3. Version 1.00
initial version. Version 1.01 19940919 removes records in
the Data Dictionary/Domain module for attributes for which no
information is known on the domain (such records are
nonconforming to the standard) and updates Identification module
to be compliant to version 1.0 of the TVP. Version 2.00
19950411 has been assembled to describe the attribute
restructuring done to support 1:2,000,000 scale DLGs. In this
restructuring records enumerating the domain for the term
LAND_GRANT were deleted. These enumerated value descriptions
are now carried as attribute values of the newly defined term
LANDGRANTNAME. Version 3.00 19951012 is built on version 1.01
19940919 and does not include enhancements made to version 2.00
19950411. Version 3.00 was assembled to support the changes
made in the 7/95 version of the Standards for Digital Line
Graphs Part 3 Attribute Coding. Version 3.00 also includes
changes made to support DLG3 Core (DLG with Framework content)
specifications. Version 3.00 also adds back the records in the
Data Dictionary/Domain module that were deleted in version 1.01
(these records have been rearranged to be conforming to the
standard.)
COMPLETENESS DATA QUALITY REPORT for master data dictionary for USGS DLG3 data. This master data dictionary is used to transfer DLG3 files which use the attribute coding scheme of the Standards for Digital Line Graphs, Part 3. This data dictionary is current as of the 7/95 change to the Standards for Digital Line Graphs, Part 3. This data dictionary includes some entities and attributes which are not currently collected in DLG3 files but were in the past and thus may occur in older DLG3's. This data dictionary includes some entities and attributes which are not in the Standards for Digital Line Graphs but are used by the USGS to support 1:2,000,000scale DLG's and some 1:100,000scale DLG's for federallyadministered lands. This data dictionary also contains codes not found in the Standards for Digital Line Graphs that were included to support DLG3 Core (DLG3 with Framework content) specifications.
Certain node/geometry and topology (GT)polygon/chain
relationships are collected or generated to satisfy topological
requirements. (The GTpolygon corresponds to the DLG area).
Some of these requirements include: chains must begin and end at
nodes, chains must connect to each other at nodes, chains do not
extend through nodes, left and right GTpolygons are defined for
each chain element and are consistent throughout the transfer,
and the chains representing the limits of the file (neatline)
are free of gaps. The tests of logical consistency are
performed by PROSYS (USGS) program. The neatline is generated
by connecting the four corners of the digital file, as
established during initialization of the digital file. All data
outside the enclosed region are ignored and all data crossing
these geographically straight lines are clipped at the neatline.
(Exception: Early files may have area pointings outside of the
neatline, for those areas which were too small to place the area
pointing within, given software constraints at the time of
collection.) Data within a specified tolerance of the neatline
are snapped to the neatline. Neatline straightening aligns the
digitized edges of the digital data with the generated neatline,
that is, with the longitude/latitude lines in geographic
coordinates. All internal polygons are tested for closure;
early files were checked using plots, later files were checked
using PROSYS. Certain attributes and/or entities, e.g. closure
line, convey data quality information; for details refer to the
SDTS Data Dictionary Modules. Throughout the transfer, null
values are denoted by adjacent delimiters. When a subfield,
either userdefined in Attribute Primary and Attribute Secondary
Module records, or in other SDTS Module records, is implemented
as fixedlength, the following null scheme is used: (a) when
information to be encoded in the subfield is known to be not
applicable (undefined, not relevant), then the subfield is
valued by a string of spaces; and (b) when the information to
be encoded is relevant but unknown (or missing), then the
subfield is valued by a string of question marks "?".
Accuracy of this digital data (if not digitally revised), is based upon the use of source graphics which are compiled to meet National Map Accuracy Standards. NMAS horizontal accuracy requires that at least 90 percent of points tested are within 0. 02 inches of the true position. The digital data are estimated to contain a horizontal positional error of less than or equal to 0.003 inches standard error in the two component directions relative to the source graphic. NMAS vertical accuracy requires that at least 90% of well defined points tested be within one half contour interval of the correct value. Comparison to the graphic source is used as control to assess digital positional accuracy. Cartographic offsets may be present on the graphic source, due to scale and legibility constraints. Digital map elements require edge alignment between data sets. Data along each quadrangle edge are tested against the data set for the adjacent quadrangle; tests check for positional accuracy between data sets within a 0.02 inches tolerance. Features with like dimensionality, and with or without like attribution, that are within the tolerance are adjusted by moving the feature equally in both data sets. Features outside the tolerance are not moved. All disconnects are identified by edge matching flags that document the mismatch. These edge matching flags are located in the SDTS AHDR Attribute Primary Module in subfields EDGEWS, EDGEWR, EDGENS, EDGENR, EDGEES, EDGEER, EDGESS, and EDGESR. If the digital data underwent limited update revision, then the data meets at least the class 2 positional accuracy specification in the draft "United States National Cartographic Standards for Spatial Accuracy". If the digital data underwent standard update revision, then the data meets the class 1 positional accuracy specifications. Certain attributes and/or entities, e.g. BEST_ESTIMATE, convey data accuracy information; for details refer to the SDTS Data Dictionary Modules.
Attribute accuracy is tested by manual comparison of the source with hard copy plots and/or symbolized display of the digital line graph on an interactive computer graphic system; selected attributes that cannot be visually verified on plots or on screen, are interactively queried and verified on screen. In addition, PROSYS software (USGS) tests the attributes against a master set of valid attributes for the hydrography category; it also checks for selected valid attribute combinations, and for valid attributes relative to topology and dimensionality. All attribute data conform to the attribute codes current as of the date of digitizing as described in Part 3: Attribute Codes in "Standards for Digital Line Graphs", National Mapping Program Technical Instructions, USGS. Accuracy is estimated to be 98.5 percent. Certain attributes and/or entities, e.g. BEST_ESTIMATE, convey data quality information; for details refer to the SDTS Data Dictionary Modules.
REFERENCES:
DLG Digital User Guide
National Map Accuracy Standards
FIPS Publication 1731
Please visit the USGS web site for all mentioned references:
or
MAP PROJECTION PARAMETERS
Projection ALBERS Units METERS Datum HPGN Spheroid GRS1980 1st standard parallel 24 0 0.000 2nd standard parallel 31 30 0.000 central meridian -84 0 0.000 latitude of projection's origin 24 0 0.000 false easting (meters) 400000.00000 false northing (meters) 0.00000
DATA SOURCES CONTACT(S):
Name: UNITED STATES GEOLOGICAL SURVEY
Abbr. name: USGS
Address: USGS Mapping Applications Center
National Cartographic Info Center
507 National Center
Reston VA 22092
Phone: (703) 8606045
Fax: (703) 6484165
Web site: http://www.usgs.gov
Email: MACWEBMASTER@USGS.GOV
Contact Person: They will route your message to the person best
qualified to respond
FGDL CONTACT:
Name: FLORIDA GEOGRAPHIC DATA LIBRARY
Abbr. Name: FGDL
Address: Florida Geographic Data Library
431 Architecture Building
PO Box 115706
Gainesville, FL 32611-5706
Web site: http://www.fgdl.org
Contact FGDL:
Technical Support: http://www.fgdl.org/fgdlfeed.html
FGDL Frequently Asked Questions: http://www.fgdl.org/fgdlfaq.html
FGDL Mailing Lists: http://www.fgdl.org/fgdl-l.html
For FGDL Software: http://www.fgdl.org/software.html