10-02-98 This directory contains the Large-Scale Digital Line Graph (DLG) data. *** File transfer mode must be set to BINARY if your Web browser *** *** doesn't do this automatically. *** *** The data files are stored on a robotic mass-storage device so there *** *** may be a short (~10 seconds) delay while the media is retrieved *** *** If you have any questions or suggestions, please contact Customer *** *** Services at custserv@edcmail.cr.usgs.gov *** DIRECTORY STRUCTURE The directory structure for the Large-Scale DLG FTP account is defined as follows: A-Z/mapname_STATE/layer/version where: A-Z = The first character of the map name mapname = The name of the Large-Scale map STATE = The two character state code used to distinguish between duplicate map names layer = The category of data (such as hydrography or transportation) version = The version of data (1-current; 2-historical) Example: B/bismarck_ND/boundaries/version_1 is the location for the boundary layer of the Bismarck, ND quadrangle. All files for each layer are contained under the layers directory. For more information see FILE EXTENT and DATA FORMAT sections of this readme. FILE EXTENT SDTS transfers are stored as compressed "tar" archive files. Each transfer contains a complete set of files, for a specific layer and version, covering a quadrangle. The transfer naming convention is as follows: XXX.layer.V.sdts.tar.gz. XXX = a unique quadrangle identifier; which consists of quad SE coordinates preceded by a D, layer = data category name abbreviation (such as "bd" for boundary) followed by 0 (zero) and "s" or "f" ("s" is for 7.5-minute and "f" is for 15-minute) V = file version (1-current; 2-historical) sdts = denotes that the data is in SDTS format tar = represents "tar" file gz = refers to "gzip" compression The "tar" files have been compressed to speed up the download. You will need to decompress the ".gz" files before untarring the SDTS files. For information about tar and unzip see the FILE COMPRESSION section of this "README". You must download the Master Data Dictionary (MDD), (00MASTERDD_LRG.SDTS) Version 3.0, which is meant to be used in conjunction with a Large Scale (DLG-3) SDTS transfer to form a fully compliant SDTS/Topological Vector Profile (TVP) transfer. The MDD can be found in this directory as a compressed tar file, (00MASTERDD_LRG.SDTS.tar.gz), or as separate uncompressed files in the 00MASTERDD_LRG.SDTS directory. Please refer to the "README" file found at /data/DLG/LARGE_SCALE/00MASTERDD_LRG.SDTS for more MDD information. ***** PLEASE NOTE THAT YOU MUST HAVE THE MASTER DATA ***** DICTIONARY AT THE SAME DIRECTORY LEVEL AS THE DATA. Unzipping, then untarring SDTS data creates several files all having a .DDF extension. Refer to "DLG-3 SDTS Transfer Description" draft document for details about the SDTS format. It may be found at the SDTS information ftp site in two formats. Word Perfect - ftp://sdts.er.usgs.gov/pub/sdts/datasets/tvp/dlg3/dlg3.wp Post Script - ftp://sdts.er.usgs.gov/pub/sdts/datasets/tvp/dlg3/dlg3.ps FILE COMPRESSION The SDTS transfers are stored as compressed "tar" archive files. Each transfer is comprised of several files which are combined with the Unix "tar" command and compressed using the GNU "gzip" utility. To extract the SDTS modules, the following UNIX command could be used: gunzip < hydro.sdts.tar.gz | tar xvBf - In MSDOS, the command is: gzip -d hydro.sdts.gz WARNING! Some uncompression utilities automatically default to "Smart TAR CR/LF translation". This setting must NOT be used as it will introduce errors in the data! (See "FTP SITES" for a list of places where DOS and MAC versions of tar can be downloaded.) Note: If you do not have access to gzip, the FTP server will uncompress the files as you retrieve them if you omit the gz extension. For example, in a ftp session, to retrieve the file "D4212204_bd0s.1.sdts.tar.gz" without compression, type: "get D4212204_bd0s.1.sdts.tar" Note that the uncompressed files are typically five times larger than the compressed versions and will take five times longer to transmit. Most web browsers will allow FTP retrieval as well. For a list of gzip sites see "FTP SITES". FTP SITES UNIX gzip: ftp://prep.ai.mit.edu/pub/gnu ftp://wuarchive.wustl.edu/systems/gnu MAC gzip and tar: ftp://mirrors.aol.com/pub/mac/util/compression macgzip0.3b2.sit.hqx suntar2.03.cpt.hqx MSDOS gzip and tar: ftp://prep.ai.mit.edu/pub/gnu gzip-1.2.4.tar ftp://ftp.uu.net/systems/ibmpc/msdos/pcroute tar.exe Example FTP: ftp prep.ai.mit.edu user name: password: cd /pub/gnu set binary get quit DATA FORMAT The Large-Scale DLG data files are available in two distribution formats: Spatial Data Transfer Standard (SDTS), and Optional. The Optional format is available "at cost" on various magnetic media in addition to CD-ROM through the Earth Science Information Center address provided below. For a complete explanation of the Large-Scale DLG format see the USGS National Mapping Program, Technical Instructions, Data User's Guide 1 "Digital Line Graphs from 1:24,000-Scale Maps". For details about the SDTS format see the "DLG-3 SDTS Transfer Description" draft document. These booklets can be ordered, for a small fee, from the Earth Science Information Center at the following address: Earth Science Information Center U.S. Geological Survey 507 National Center Reston, VA 20192 Tel: 703-648-6045 or 800-USA-MAPS Fax: 703-648-5548 Technical Instructions can also be obtained from the following anonymous FTP accounts: User Guide: ftp://mapping.usgs.gov/pub/ti/DLG/24kdlgguide (User Guide) SDTS Transfer Description and other SDTS documents: ftp://sdts.er.usgs.gov/pub/sdts/ The following URL addresses also provide additional information: SDTS home page: http://mcmcweb.er.usgs.gov/sdts/ General Large-Scale DLG information: http://edcwww.cr.usgs.gov/glis/hyper/guide/usgs_dlg Global Land Information System (GLIS) (allows you to connect to GLIS and search against the Large-Scale DLG data base: http://edcwww.cr.usgs.gov/glis/glis.html BACKGROUND INFORMATION: The Large-Scale Digital Line Graph (DLG) data, which are produced by the U.S. Geological Survey (USGS), are digital representations of cartographic information. These DLG data files are derived from USGS topographic maps published as 7.5-minute quadrangles at 1:24,000- or 1:25,000-scale. Where 7.5-minute coverage was not available, other sources were used. The Large-Scale DLG data are sold in nine layers, including: Public Land Survey System (PLSS), boundaries, transportation, hydrography, hypsography, surface cover, non-vegetative surface features, survey control and markers, and manmade or cultural features. **** FOR ADDITIONAL INFORMATION VISIT THE SDTS **** **** WEB SITE OR E-MAIL THE SDTS TASK FORCE **** POINT OF CONTACT: U.S. Geological Survey | E-mail: sdts@usgs.gov SDTS Task Force, MS 821 | Web: http://mcmcweb.er.usgs.gov/sdts 1400 Independence Road | FTP: sdts.er.usgs.gov (144.47.162.236)