Product Support

2101 - Accessing Geospatial Data on the Internet for the Mapping Toolbox

About Geospatial Data Files and Formats
Vector Geospatial Data
Raster Geospatial Data
Portals to Global, Regional and Local Area Geodata
MATLAB Functions that Access Internet Data Directly
Abbreviations, Names, and Home Pages for Organizations
Disclaimer
Notes

About Geospatial Data Files and Formats

Many vector and raster data formats have been developed for storing geospatial data in computer files. Some are widely used, others are obscure. Some are simple, while others have elaborate record and file structures. Some formats are government or international standards, others are simply popular. A format can be general-purpose, specific to a narrow class of data, or may be used just to publish a certain data set.

Using the Mapping Toolbox you can read geodata files in generic exchange formats (e.g., ESRI® shapefiles, GeoTIFF and SDTS files), which a variety of mapping and image processing applications can also read and write. You can also read files that are in a variety of special formats designed to exchange specific sets or kinds of geodata (e.g., GSHHS, DCW, DEM, and DTED files). You can order, and in many cases, download such data over the Internet from public agencies and private distributors. When fees are charged, they are generally quite modest.

The Mapping Toolbox provides generalized sample data in the form of data files for the entire Earth and its major regions, as well as some more detailed demo geodata files covering small areas. These datasets are frequently used in the code examples provided in the Mapping Toolbox documentation. You can find them, along with the demos that use them, in matlabroot/toolbox/map/mapdemos. You can list them, along with their metadata and the demos that use them by typing in MATLAB

ls(fullfile(matlabroot, 'toolbox', 'map', 'mapdemos'))

The following two tables describe a small but useful subset of geodata resources on the Internet, providing URLs from which you can obtain documentation, metadata, and the data sets themselves. The first table describes vector data sets and data products, and the next one describes raster data sets and products. Within each table, entries are arranged alphabetically by the data set /or data product name. Click any numbered footnote in the right-hand column to access the page on the Web. Click on any function name to read its documentation page on the MathWorks Web site.

Vector Geospatial Data

Some of the more commonly-used vector (feature) geospatial data sets available over the Internet are described below. Click their names for information on locating the data on the Internet and the Mapping Toolbox commands that read this form of data:

Vector Data Set or Data Product	Data Provider	Associated Toolbox Functions	Function Purpose	Internet URLs for Documentation and Data (HTTP or FTP)
Canadian provincial and Mexican state boundaries in zipped shapefile format	NOAA/NWS	unzip shapeinfo shaperead shapewrite geoshow mapshow mapview	Expand a zipped archive Read, write, display, or obtain information about geospatial data and associated attributes in shapefiles	Documentation link: [1] Canada data link: [2] Mexico data link: [3]
Digital Chart of the World (DCW)	DMA, ESRI	dcwdata dcwgaz dcwread dcwrhead	Read, search, or select data or headers from the DCW, prepared for the U.S. DMA by ESRI in 1992	Documentation links: [1]; [2] ; [3] Data link: [4] (by country and U.S. state; fees charged); [5] (by country or world region, free via browser GUI)
ESRI shapefiles (various content)	ESRI and many other sources	shapeinfo shaperead shapewrite geoshow mapshow mapview	Read, write, display, or obtain information about geospatial data and associated attributes in a shapefile	Documentation link: [1] For data links, see entries for TIGER, U.S. National Atlas, and U.S. coastlines
Federal Information Processing Standard (FIPS) Place Codes	NIST	fipsname	Read Topographically Integrated Geographic Encoding and Referencing (TIGER) thinned boundary file FIPS names	Official numeric and alphabetic place codes for U.S. civil subdivisions State and County Data:[1] State Data: [2] State FIPS Doc: [3] County FIPS Doc: [4]
Fifth Fundamental Catalog of Stars (FK5)	U. of Strasbourg	readfk5	Read data from the FK5 catalog	Documentation links: [1]; [2] Data links: [3]; [4]
Global Self-Consistent Hierarchical High-resolution Shoreline (GSHHS)	NOAA/NGDC	gshhs	Read Global Self-Consistent Hierarchical High-resolution Shoreline data	Doc and data link: [1] Data and software (original format): [2] Data (shapefiles, v. 1.3 [3], v. 1.2 [4])
TIGER/Line® files	Census	tgrline shapeinfo shaperead	Read data from TIGER/Line files for 1990-2002 in native TIGER or shapefile formats	Documentation and Data link: [1] Data (for 2000, in shapefile format): [2] Note: TIGER contents and formats can vary from one edition to the next; you may be able to find TIGER data in shapefile format that suits your purposes.
TIGER cartographic boundary files	Census	shapeinfo shaperead geoshow mapshow mapview	Read TIGER cartographic boundary files for the U.S. in shapefile format	Documentation link: [1] Data: [2] (this site contains downloadable boundary files for census geographies in ESRI Ungenerate, E00, and shapefile formats; use shapefile when importing to Mapping Toolbox.
U.S coastlines, historical data	NOAA	shapeinfo shaperead geoshow mapshow mapview	Read or obtain information about geospatial data and associated attributes in a shapefile	Documentation, Metadata, and Data in Shapefile format: [1] .
U.S. National Atlas	USGS	shapeinfo shaperead geoshow mapshow mapview	Read/display U.S. National Atlas data layers in shapefile format	Documentation link [1] Data link [2] Note: some files are attributes only (DBF); geodata is also provided in SDTS format
Vector Smart Map Level 0 (VMap0)	NGA	vmap0data vmap0read vmap0rhead vmap0ui	Extract and read selected data from the Vector Map Level 0 files on CD-ROMs or disk via commands or GUI.	Documentation links: [1]; [2] ; [3] Data (on CD-ROM): [4]; (Web download; note instructions on WinZip settings) [5]
World coastlines from various sources	NGDC/USGS	load *	Read a data file into workspace	Data link (GUI to specify extent and format, including MATLAB®, for various sources of vector coastlines): [1]

Raster Geospatial Data

Some of the more commonly-used raster (gridded) geospatial data sets available over the Internet are described below. Click their names for information on locating the data on the Internet and the Mapping Toolbox commands that read this form of data:

Raster Data Set or Data Product	Data Provider	Associated Toolbox Functions	Function Purpose	Internet URLs for Documentation and Data (HTTP or FTP)
Digital Elevation Models in original format	USGS	usgsdem usgsdems usgs24kdem demdataui	Read DEM files, filenames and activate DEM data user interface	Documentation link: [1] Documentation and data links: [2]
Digital Elevation Models in SDTS format	USGS	sdtsdemread sdtsinfo geoshow mapshow mapview	Read or obtain information about an SDTS DEM data set	Documentation links: [1]; [2]; [3]; [4] Data link: [5]
Digital Terrain Elevation Data (DTED)	DMA / NIMA / NGA	dteds dted	Search for or read local network DTED data	Documentation links: [1] Data links: [2]
Earth Topography, 2-Minute (ETOPO2)	NOAA/ NGDC	etopo	Read data from the ETOPO2 or ETOPO5 data set	Documentation link: [ 1] Data (binary) link: [2] (either ETOPO2.dos.bin or ETOPO2.raw.bin can be used)
Earth Topography – 5 Minute (ETOPO5)	NOAA / NGDC	etopo	Read data from the ETOPO2 or ETOPO5 data set	Documentation links: [1] Data links (binary): [2] (only ETOPO5.DOS should be used)
Geographically referenced TIFF images (GeoTIFF)	various	geotiffread geoshow mapshow worldfileread	Read GeoTIFFs and/or worldfiles to obtain data grids and referencing matrices	Documentation links: [1] USGS Digital Raster Graphics (scanned topo sheets) Data: [2]
Global Land Cover Characteristics (GLCC)	USGS	avhrrgoode avhrrlambert	GLCC data products (derived from AVHRR) in Goode or Lambert projections	Documentation links: [ 1 ]; [2] Data links: [3]
Global Land 1-km Base Elevation (GLOBE)	NOAA / NGDC	globedems globedem	Read GLOBE 30-arc-second (1 km) digital elevation filenames and data	Documentation and Data links: [1] Data links: [2]
30-arc-sec (1 km) Global Elevation data (GTOPO30)	USGS	gtopo30s gtopo30	List and read GTOPO30 files	Documentation links: [1] Data links: [2]
Global 2-minute (4 km) satellite topography and bathymetry data	Scripps	satbath	Read binary topographic data grid	Documentation links: [1]; [2] Data links: [3]; [4] Note: Download the latest data file topo_8.2.img; if using a MATLAB release prior to version R2007a, rename the data file to 'topo_6.2.img'.
TerrainBase topography & bathymetry binary and ASCII grid files	NOAA / NGDC	tbase	Read data from the TerrainBase data set	Documentation links: [1]; [2] TerrainBase 5-minute data: [3] Note: Higher-resolution data can be ordered on CD-ROM.
U.S. coastal nautical chart images	NOAA / NOS	geotiffread geoshow mapshow mapview	Read scanned nautical chart GeoTIFF and worldfiles (1:20K and smaller)	Data (via UI to select a specific chart): [1]
U.S. National Elevation Dataset (NED)	USGS	imread * geotiffread geotiffinfo geoshow mapshow mapview	Read data in TIFF or GeoTIFF format	Documentation links: [1] Data (at 1/3 and 1 arc-sec resolutions in ArcGRID, TIFF, GridFloat, and BIL-meters formats): [2]
WGS84 EGM96 Geoid Model	NGA, NASA	egm96geoid	Read 15-minute gridded geoid heights from the EGM96 geoid model.	Documentation links: [1] Documentation and Data links: [2]

Portals to Global, National, Regional and Local Area Geodata

You can access a worldwide network of geodata servers through the U.S. Federal Geographic Data Committee (FGDC) National Geodata Clearinghouse web portal at http://clearinghouse3.fgdc.gov/. The Geospatial Data Clearinghouse is a collection of several hundred spatial data servers that provide access to digital geographic data primarily for use in geographic information (GIS), image processing systems, and other modeling software. You can search any of these data collections based on their descriptions or metadata. The Clearinghouse Search Wizard shown below, at http://clearinghouse1.fgdc.gov/servlet/FGDCWizard, and several other sites included at the Clearinghouse web portal mentioned above, is one of several interfaces for browsing geospatial data and metadata worldwide. The page http://clearinghouse4.fgdc.gov/registry/clearinghouse_sites.html enumerates the sites involved in the clearinghouse. You can find other data and metadata resources at the Geospatial One-Stop e-government gateway for improving access to geospatial information and data at http://www.geodata.gov/.

Two Federal Government Web sites bundle vector and raster geodata layers for download in several file and archiving formats: the National Elevation Dataset (http://ned.usgs.gov/) and Seamless Data Distribution System (SDDS, http://seamless.usgs.gov/website/Seamless).

Individual, tiled USGS Digital Elevation Models (DEM) will not be offered through the new Tiled Data Delivery System (TDDS). The current official National Map elevation data, National Elevation Dataset (NED), incorporates the DEMs and offers the best available elevation product through Seamless Data Distribution System (SDDS). The DEMs will still be available for purchase through EarthExplorer.

In the United States, state and local governments maintain geospatial data, for example land use, parcels, highways, and other elements of infrastructure, demographics, and economics. Much of it is digital, and a significant amount is online and publicly accessible. One useful starting point for exploring local geodata resources is an index of U.S. state GIS, geodata web sites, and clearinghouses.

You can browse environmental and geophysical data for many regions of the earth via the Global Change Master Directory (GCMD) portal. Some of the topics for which you can access data sets are Agriculture, Atmosphere, Biosphere, Climate Indicators, Human Dimensions, Hydrosphere, and Land Surface. The portal also connects you to data services in the following areas:

Data Analysis and Visualization
Data Management / Data Handling
Education / Outreach
Environmental Advisories
Hazards Management
Metadata Handling
Models
Reference and Information Services

GCMD is the North American Coordinating Node of the Committee on Earth Observation Satellites (CEOS) International Directory Network, http://idn.ceos.org/.

EarthExplorer is a Web site operated by the EROS Data Center through which you can query and order satellite images, aerial photographs, and cartographic products through the U.S. Geological Survey on CD-ROM, DVD, magnetic tape, and Internet file transfer. Fees are charged for files, whether shipped on media or downloaded via FTP. You can log in as a guest or registered user at http://earthexplorer.usgs.gov and specify areas of interest by clicking and zooming into maps or by entering geographic coordinates. Data sets available through the site are listed in the following table. Note that not all the formats used for these data sets are recognized by the Mapping Toolbox.

Satellite Imagery	Advanced Very High Resolution Radiometer Declassified Satellite Imagery - 1 (1996) Declassified Satellite Imagery - 2 (2002) EO-1 Advanced Land Imager EO-1 Hyperion ETM+ (Landsat 7, June 1999 - May 2003) ETM+ SLC-off (Landsat 7, July 2003 - present) Landsat Orthorectified TM Mosaics MSS (Landsat 1-5, July 1972 - October 1992) SPOT (Search Only) TM (Landsat 4-5, July 1982 - present)
Aerial Photography	Digital Orthophoto Quadrangles Digital Orthophoto Quadrangles - County National Aerial Photography Program (1987-present) National High Altitude Photography (1980-1989) Space Acquired Photography Survey Photography USGS High Resolution Photography
Digital Line Graphs	Digital Line Graph - 1:100,000 scale Digital Line Graph - Large Scale
Elevation	Digital Elevation Model - 15 Minute Digital Elevation Model - 30 Minute Digital Elevation Model - 7.5 Minute National Elevation Dataset (Pre-Defined Areas
Maps	Digital Raster Graphics National Atlas of the United States

MATLAB Functions that Access Internet Data Directly

The following MATLAB functions can read a file identified by a URL and write the file to a local directory or load it into your MATLAB Workspace:

geotiffread	Read a georeferenced image from GeoTIFF file
gunzip	Uncompress files in the GNU-Zip format
imread	Read image from graphics file
untar	Extract the contents of a Tar-file
unzip	Extract the contents of a Zip-file
urlread	Returns the contents of a URL as a string
urlwrite	Save the contents of a URL to a file

These functions do not access web services, they just read files from URLs. All except urlread and urlwrite can read files on local and network file systems using path syntax as well.

Example: Write a USGS 1:24,000 scale Digital Elevation Model to your current directory, and then import it to the workspace using the usgs24kdem function:

demFilename = 'sanfranciscos.dem';
dataServerURL = 'http://bard.wr.usgs.gov/bard/dem/dems24k/sanfrancisco/';
URL = [dataServerURL demFilename];
urlwrite(URL, demFilename);  
[lat, lon, Z] = usgs24kdem(demFilename, 2);

For additional details, see the Mapping Toolbox documentation for usgs24kdem.

Abbreviations, Names, and Home Pages for Organizations

Census	Bureau of the Census (U.S. Dept. of Commerce)
CEOS	Committee on Earth Observation Satellites
DMA	Defense Mapping Agency (now NGA, U.S. Dept. of Defense)
ESRI	Environmental Sciences Research Institute (private company, Redlands CA, U.S.A.)
FGDC	Federal Geographic Data Committee
FIPS	Federal Information Processing Standard (administered by NIST)
GCMD	Global Change Master Directory (A CEOS clearinghouse housed at NASA)
NASA	National Aeronautics and Space Administration (U.S.A.)
NGA	National Geospatial Intelligence Agency (U.S. Dept. of Defense)
NGDC	National Geophysical Data Center (NOAA)
NIMA	National Imagery and Mapping Administration (now NGA, U.S. Dept. of Defense)
NIST	National Institute of Standards and Technology (U.S. federal agency)
NOAA	National Oceanic and Atmospheric Administration (U.S. Dept. of Interior)
NOS	National Ocean Service, (NOAA)
Scripps	Scripps Institution of Oceanography (private nonprofit, La Jolla CA, U.S.A.)
USGS	U.S. Geological Survey (U.S. Dept. of Interior)

Disclaimer

The MathWorks provides the information on this page as a courtesy to users of the Mapping Toolbox. The MathWorks does not warrant the accuracy, timeliness, or fitness for use of any data set listed above, and makes no endorsement of any data vendor mentioned. Web addresses (URLs) for data may disappear or change, making some of the above links unusable. If you are a licensed MATLAB user and find that any of the above pages is no longer accessible, please report the URL to the MathWorks at http://www.mathworks.com/support/contact_us/index.html or call 508-647-7000 and press 5.

Notes

ESRI is a registered trademark of Environmental Systems Research Institute, Inc. MATLAB is a registered trademark of The MathWorks, Inc. TIGER and TIGER/Line are registered trademarks of the United States Census Bureau.

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