cfr 250/590 introduction to gis, autumn 1999 data search & import © phil hurvitz,...

© Phil Hurvitz, 1999-2000

CFR 250/590 Introduction to GIS, Autumn 1999

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Data Search & Import

Overview

• Web search engines• NSDI GeoSpatial Data Clearinghouse• USGS GeoData site• University of Washington Map Library

GeoSpatial Data Archive

• Searching for data

• Importing data

• ARC/INFO interchange file• SDTS files

• USGS DEM data• USGS DLG data



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Searching for data

• Web search engines

• NSDI GeoSpatial Data Clearinghouse

• USGS GeoData site

• University of Washington Map Library GeoSpatial Data Archive



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Searching for data: Web search engines

• The primary method for searching for general data on the net

• Keyword searching

• Logical parsing of searches

• Search is far and wide

• Possible to use meta-searchers

• Graphical results

• Low precision



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• Search

“GIS&data”

• Results are good



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• Search

“GIS&data&Washington”

• Results are bad



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• Why are web search engines not the best tool for searching GIS data?

• Spiders only find and index keywords, not meaning

• Searching for keywords is not efficient

• Too many erroneous matches

• Not a true database query

• No spatial coordinates in normal search engines

• Too many dead ends and broken links

• No standard format for searching various engines



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Searching for data: NSDI GeoSpatial Data Clearinghouse (GDC)

• National Spatial Data Infrastructure (NSDI)

• Federal Geospatial Data Committee

• Better methods are needed for searching for GIS data

• Federal agencies mandated to increase access to geospatial data

• Development of common search engine

• Standardized approach

• Queryable databases (Z39.50 international library standard)

• Specific server network built on top of the Network

• Metadata is the keystone



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Searching for data: NSDI GDC: Metadata

• Content-standardized metadata is the foundation of a robust searching tool

• Records for individual data sets contain data for specific fields, e.g.,

• Title

• Abstract

• Spatial extent

• Data type

• Currency of time scale

• Source scale

• Developer/Contact information



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Searching for data: NSDI GDC: Indexed databases

• Metadata records are indexed into international library Z39.50 standard databases

• Specific sites containing indexes (nodes) are registered with search server sites

• Searches can be limited to individual nodes or to many nodes

• Databases are searchable across TCP/IP networks

• Searching functions are imbedded in web interfaces

• Results are displayed in web pages



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Searching for data: NSDI GDC: Searching

• Search by place name orgeographic location



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• Search by time period

• Search by keyword in various fields



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• Select node to search



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Searching for data: NSDI GDC: Results

• Number of hits is displayed

• Individual records can be browsed



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• Individual record titles can be browsed



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• Individual records can be read

• Particular data are hyperlinked



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• Find out where to get copies of the data



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Searching for data: USGS GeoData site

• A tremendous amount of data area available for “free”

• Data sets representing USGS topographic quadrangles

• Data from paper maps converted to digital format

• DEM (raster elevation) data

• Vector data for a variety of themes

• Variety of source scales



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Searching for data: USGS GeoData site

• 7.5’ (1:24,000) topographicquadrangle vector data series

• Always review 00README files



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Searching for data: USGS GeoData site: Downloading

• Interactive quadrangle searching

• Individual files are downloadable

• Text-only searching also available



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Searching for data: University of Washington Map Library GeoSpatial Data Archive (WAGDA)

• Staffed by “GIS Librarian” Jenny Stone

• Should be your first stop when searching for GIS data

• Depository library

• Suzzallo Library basement

• Data repository for Washington and PNW data

• On-line and off-line data sets

• City of Seattle GIS database

• 10 m USGS DEMs

• Large collection of paper maps & aerial photos



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Searching for data: WAGDA Web page



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Searching for data: WAGDA Web page



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Importing data

• ARC/INFO interchange file

• SDTS files

• USGS DEM data

• USGS DLG data



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Importing data: ARC/INFO interchange file

• ARC/INFO has been a leading software

• Very common file format

• Known as “interchange,” “export,” or “E00” file

• Easy to transfer from machine to machine or across file system; easy to distribute via the Network

• Can be imported into ARC/INFO format for use in ArcView



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Importing data: ARC/INFO file structure

some of these files

are associated with this data set



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Importing data: ARC/INFO file structure

• Problematic file structure for file management

• Directories for ARC/INFO data sets cannot be altered, copied, or moved arbitrarily

• Interchange file “packages” coverage directoryand info files into a single interchange file



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Importing data: ARC/INFO file structure: Importing

menu access to importing application



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• GUI-controlledimport function

Importing data: ARC/INFO file structure: Importing

• data imported asARC/INFO coverage



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Importing data: SDTS files

• USGS digital elevation model (DEM) data

• USGS digital line graph (DLG) data



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Importing data: SDTS files: USGS DEM data

• publicly available data sets

• distributed by USGS in SDTS file format

• public-domain tools for conversion from SDTS



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public-domain converter

input SDTS output DEM



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• ArcView imports USGS format DEMs



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Importing data: SDTS files: USGS DLG data

• vector format data

• publicly available data sets

• distributed in zipped or SDTS file format

• public-domain tools for conversion from SDTS to DXF

• ARC/INFO or other commercial softwarefor full conversion of SDTS to GIS data sets



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Importing data: SDTS files: Importing STDS DLG to DXF



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Importing data: SDTS files: Importing STDS DLG to ARC/INFO coverage

cfr 250/590 introduction to gis, autumn 1999 data search & import © phil hurvitz,...

Documents

particular data

general data

individual data sets

free data sets

data area available

gis data federal agencies

normal search engines

time period search