| USGS 1:24,000 DLG Roads | |
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Data format: SDE Feature Class File or table name: GISLIB.TRANS_RDS_24K_USGS_2002 Coordinate system: Transverse Mercator Theme keywords: Digital Line Graphs (DLG), transportation, roads, major roads, interstate highways, state highways, U. S. highways, turnpikes, local roads, large scale |
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Abstract:
The DLG/SDTS data were created by reformating DLG-O data into the SDTS standard. The SDTS transportation catagory quads that are within St Johns River Water Management District were downloaded from the USGS site and then mapjoined into a District wide coverage. This layer also includes those quads that were processed by CognoCarta GIS.
Digital line graph (DLG) data are digital representations of cartographic information. DLGs of map features are converted to digital form from maps and related sources. Large-scale DLG data are derived from USGS 1:20,000-, 1:24,000-, and 1:25,000-scale 7.5 minute topographic quadrangle maps and are available in nine categories: (1) hypsography, (2) hydrography, (3) vegetative surface cover, (4) non-vegetative features, (5) boundaries, (6) survey control and markers, (7) transportation, (8) manmade features, and (9) Public Land Survey System. All DLG Data distributed by the USGS - Level 3 (DLG-3), which means the data contain a full range of attribute codes, have full topological structuring, and have passed certain quality-control checks. |
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Metadata elements shown with blue text are defined in the Federal Geographic Data Committee's (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM). Elements shown with green text are defined in the ESRI Profile of the CSDGM. Elements shown with a green asterisk (*) will be automatically updated by ArcCatalog. ArcCatalog adds hints indicating which FGDC elements are mandatory; these are shown with gray text.
The DLG/SDTS data were created by reformating DLG-O data into the SDTS standard. The SDTS transportation catagory quads that are within St Johns River Water Management District were downloaded from the USGS site and then mapjoined into a District wide coverage. This layer also includes those quads that were processed by CognoCarta GIS. Digital line graph (DLG) data are digital representations of cartographic information. DLGs of map features are converted to digital form from maps and related sources. Large-scale DLG data are derived from USGS 1:20,000-, 1:24,000-, and 1:25,000-scale 7.5 minute topographic quadrangle maps and are available in nine categories: (1) hypsography, (2) hydrography, (3) vegetative surface cover, (4) non-vegetative features, (5) boundaries, (6) survey control and markers, (7) transportation, (8) manmade features, and (9) Public Land Survey System. All DLG Data distributed by the USGS - Level 3 (DLG-3), which means the data contain a full range of attribute codes, have full topological structuring, and have passed certain quality-control checks.
DLG's depict information about geographic features on or near the surface of the Earth, terrain, and political and administrative units. These data were collected as part of the National Mapping Program
There are two tiles in Northeast Florida, Edgewater and New Smyrna Beach that have both arc errors and attribute errors. When the USGS DOQQ is placed behind the arcs it cannot be determined what polygons or arcs match each other along the western part of the border of these two tiles. The explaination to this was given by the USGS as follows: "The New Smyrna Beach quad was part of the Palatka, FL NAD27->NAD83 conversion only. The Edgewater, FL quad was part of the Orlando, FL Digital Limited Update -- archived into the data base in April, 2000 When exterior edge alignment was performed on the Orlando project, the (unrevised) New Smyrna Beach hydro file was pulled from the data base and the edge flags set. Because of the edge flag change, as the Orlando project was archived into the data base, the New Smyrna Beach file was also resubmitted." Full explanation of Revision Standards can be found at: http://rockyweb.cr.usgs.gov/nmpstds/dlgstds.html under Part 1: Template Development and Use, Standards for 1:24,000-Scale Digital Line Graphs and Quadrangle http://rockyweb.cr.usgs.gov/nmpstds/acrodocs/dlgqmap/1dqm0401.pdf
ground condition
The St. Johns River Water Management District prepares and uses information for its own purposes and this information may not be suitable for other purposes. This information is provided "as is". Further documentation of this data can be obtained by contacting: St. Johns River Water Management District, Division of Integrated Application Systems, Post Office Box 1429, Palatka, Florida, 32178-1429, (386) 329-4500.
P.O Box 1429
Refer to Positional_Accuracy element
Topological requirements include: lines must begin and end at node points, lines must connect to each other at nodes, lines do not extend through nodes, left and right areas are defined for each line element and are consistent throughout the file, and the lines representing the limits of the file (neatline) are free of gaps. The tests of logical consistency were performed by the USGS PROSYS program. The Neatline was generated by connecting the four corners of the digital file, as established during initialization of the digital file. All data outside the enclosed region were ignored and all data crossing these geographically straight lines were clipped at the neatline. Data within a specified tolerance of the neatline were snapped to the neatline. Neatline straightening aligned the digitized edges of the digital data with the generated neatline, that is, with the longitud/latitude lines in geographic coordinates. All internal areas were tested for closure using PROSYS.
For Digital Revision Status = Not Revised: Data completeness reflects the content of the source quadrangle. Features may have been eliminated or generalized on the source graphic, due to scale and legibility constraints. For Digital Revision Status = Limited Update: This file has undergone limited update digital revision. The file contains only: those features that are photoidentifiable on monoscopic source, supplemented with limited ancillary source, and those features, present on the original source quadrangle, that can not be reliably photoidentified but that are not considered particularly prone to change. For Digital Revision Status = Standard Update: This file has undergone standard update digital revision. The data completeness of this file meets NMD Standards for feature content.
For Digital Revision Status = Not Revised
For Hypsography, Hydrography, and Survey Control and Markers Only: For digital Revision Status = Not revised:
spatial and attribute information
SDTS transportation datasets were downloaded from the USGS ftp site by individual quads. On completion of the download, the quads were converted into coverages using the sdts2cov.aml provided by the USGS. Topology was checked and any corrections required were made to the quads. Inorder to mapjoin all the quads certain items required removal using the DROPITEMS command in ARC/INFO. The number of items that were dropped varied by quad only those items consistent with all quads were retained. The quads were appended together and neatlines removed. The coverage was randomly checked for edgematching and cleaned using a fuzzy tolerance of 0.5. Detailed methodology and amls used can be found under enclosures.
For Digital Revision Status = Not digitally revised: This Digital Line Graph was digitized from the USGS source 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, which all resulted in a scanning/digital resolution of at least 0.001 inches. Stable base scanning process: the resulting raster data were vectorized and then attributed on an interactive editing station: paper map scanning process: the resulting raster data were vectorized and then attributed on an interactive editing station. The stable base resulting raster data were then manually digitized and attributed on an interactive editing station. The paper map resulting raster data were then manually digitized and attributed on an interactive editing station. Manually digitizing from either a stable-based copy of the graphic material or a paper map using a digitizing table to capture the digital data; attribution was performed either as the data were digitized or on an interactive editing station after the digitizing was completed. The determination of the DLG production method was based on vaious criteria, including feature density, featuer 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. The DLG data were checked for position and/or classification by one or more of the following processes: - comparing plots of the digital data to the graphic source or to the digital raster scan.
For Digital Revision Status = Limited Update: This file has undergone limited update digital revision. Limited update revision uses monoscopic imagery and limited ancillary source with no field verification.
For Digital revision Status = Standard Update: This file has undergone standard update digital revision. Standard update revision uses stereoscopic imagery, with field verification.
Cognocarta process: Once individual tiles were downloaded from the USGS and converted into Arc Coverages using Scott Whitaker's (Mapping Division, USGS) sdts2acov.aml, the neatline was removed. Step two was to EDGEMATCH the coverages using the ARC feature class. Coverages were then MAPJOINED and BUILT to rebuild topology
Dataset copied.
Internal feature number.
ESRI
transportation attribute code
ESRI
description of transportation feature and defines entity label
ESRI
ESRI
ESRI
ESRI
ESRI
ESRI
ESRI
indicates if there has been a photo revision
Number of lanes
width of road
Primary route number
Alternate or additional route number
Alternate or additional route number
Alternate or additional route number
Feature geometry.
ESRI
Length of feature in internal units.
DLG3 Attibute codes are used to describe the physical and cultural characteristics of DLG node, line, and area elements. Attribute codes are used to reduce redundant information, provide enough reference information to support integration with larger data base, and describe the relationships between cartographic elements. Each DLG element has one or more attribute codes composed of a three digit major code and a four digit minor code. For example, with the 1:24000-scale DLG data, the line attribute code 050 0412 has a major code (050), meaning hydrography, with a minor code (0412) meaning stream. Entable Label coding: Entity_label Description ----------- ---------- 1700005 Cul-de-sac 1700201 Primary route, class 1, symbol undivided 1700202 Primary route, class 1, symbol divided by centerline 1700203 Primary route, class 1, divided, lanes separated 1700204 Primary route, class 1, one-way, other than divided highway 1700205 Secondary route, class 2, symbol undivided 1700206 Secondary route, class 2, symbol divided by centerline 1700207 Secondary route, class 2, symbol divided, lanes separated 1700208 Secondary route, class 2, one-way, other than divided highway 1700209 Road, class 3, symbol undivided 1700210 Road, class 4 1700211 Trail 1700212 Road, class 5, four-wheel drive 1700213 Footbridge 1700214 Road ferry crossing 1700217 Road, class 3, symbol divided by centerline 1700218 Road, class 3, symbol divided, lanes separated 1700219 Road, class 4, one-way 1700221 Road, class 3, one-way 1700222 Road in transition 1700223 Road in service facility, rest area, or viewpoint 1700401 Traffic circle 1700402 Ramp in interchange 1700403 Tollgate 1700404 Weigh station 1700405 Nonstandard section of road
U.S. Department of the Interior, U.S. Geological Survey, 1987 Digital Line Graphs from 1:24000-Scale Maps--Data Users Guide 1; Reston, Virginia Softcopies in ASCII, Wordperfect, and PostScript Format available at: ftp://mapping.usgs.gov/pub/ti/DLG/. U.S. Department of the Interior, U.S. Geological Survey, 1990, Standards for Digital Line Graphs, Reston, VA, 1994.
Post Office Box 1429
The St. Johns River Water Management District prepares and uses information for its own purposes and this information may not be suitable for other purposes. This information is provided "as is". Further documentation of this data can be obtained by contacting: St. Johns River Water Management District, Division of Integrated Application Systems, Post Office Box 1429, Palatka, Florida, 32178-1429, (386) 329-4500.
ARC/INFO Export Format - UNIX Compression
There is no charge for downloading data from the DISTRICT web site at http://www.sjrwmd.com. Data can be orded on CD-ROM as instructed on the web site.
1. Use the DISTRICT website: http://www.sjrwmd.com to download data, or 2. Call or email to organizations listed under Distributor. Spatial data are in ARC/INFO interchange formats.
Post Office Box 1429