Gtopo30 digital elevation data covers most terrestrial areas of the planet at one kilometer resolution. Framework data introduction this chapter examines sources of framework geographic data, their characteristics, and their adequacy for existing and potential agenda 21 applications. Description z,refvec gtopo30 tilename reads the gtopo30 tile specified by tilename and returns the result as a regular data grid. Webgis brings you leading information and resources for geographical information systems. The development of the european gravimetric geoid model egg07.
This site from the land processes distributed active archive center presents global topographic data gtopo30, a global digital elevation model dem with a horizontal grid spacing of 30 arc seconds. If tilename is empty or omitted, a file browser will open for interactive selection of the gtopo30. Geological surveys eros data center in sioux falls, south dakota. Ukw tools can use both sets of data either separately or together in order to provide the best data possible, without paying for it. Reading and visualization of gtopo30 data, provided by eros data center.
Gtopo30 was developed to meet the needs of the geospatial data user community for regional and continental scale topographic data. Geological surveys center for earth resources observation and science eros. Webgis geographic information systems resource gis. This data can be downloaded from the usgs earthexplorer site. Gov#find dataproducts and data availablegtopo30 info.
Gtopo30 was derived from several raster and vector sources of topographic information and has been divided into tiles for easier distribution. Geological surveys eros data center over a 3year period with support from. Gtopo30 is a global raster digital elevation model dem providing terrain elevation data with a horizontal grid spacing of 30 arc seconds approximately 1. The following organizations participated by contributing funding or source data. The data are provided in 33 contiguous tiles that cover 50 degrees of latitude by 40 degrees of longitude. This data is currently distributed free of charge by usgs and is available for download from the national map seamless data distribution system, or the usgs ftp site. How to import gtopo30 or srtm30 data into arcmap for arcgis 9. It was created between 19931996 by a team led by the us geological survey from a range of raster and vector data sources.
The data is returned at full resolution with the latitude and longitude limits determined from the gtopo30 tile. Exe program, this importer can also read in the sdts dem file format see below for more information about sdts files. Digital elevation global 30 arcsecond elevation gtopo30. Here is how to search and download the revelant data from usgs earthexplorer. Gtopo30 is a global digital elevation model dem with a horizontal grid spacing of 30 arc seconds approximately 1 kilometer. For more details on the public data distribution rights and how to download gtopo30 visit. Gtopo30 data file names for latitudelongitude quadrangle.
Jul 04, 2017 all places gis managing data questions log in to create and rate content, and to follow, bookmark, and share content with other members. Gtopo30 correct projection geonet, the esri community. The tables below provide quality summary information for all of the calipso data products. For easier distribution, gtopo30 has been divided into tiles which can be selected from the map shown above.
The global land onekm base elevation project globe, has developed a 1km gridded, qualitycontrolled global land digital elevation model dem. Get the data we will be working with gmted2010 dataset from usgs. Elevations are given in meters above mean sea level using wgs84 as a horizontal datum. For easier distribution, gtopo30 has been divided into tiles which can be selected from the. Temis gtopo30 elevation data at different resolutions. The global 30arcsecond elevation data set gtopo30 is so named, because the. Importing gtopo30 files into arcgis 9 mcgill university. If access to actual elevation values are needed for analysis, the dem must be converted. Srtm30 is a nearglobal digital elevation model dem comprising a combination of data from the shuttle radar topography mission, flown in february, 2000 and the the u. Arcmap can display gtopo30 or srtm30 elevation data directly by simply renaming the file extension from. Radio mobile rf propagation simulation software gtopo30. In this example we will make a map showing most of italy, plus sicily, sardinia, and corsica, i. It has a resolution of 30 arc seconds approximately 1km and covers the whole world. A 1 arc second data product was also produced but is not available for all countries.
Free digital terrain data, lulc data, dlg data, books, vidoes, sorftware and more. This release represents the completion of global coverage of 30arc second elevation data that have been available from the eros data center beginning in 1993. Gtopo30 is a digital elevation model for the world, developed by united states geological survey usgs. Geografica e informatica inegi of mexico, the geographical survey institute gsi. The usgs dem geometry import converter imports, manipulates and converts digital elevation model dem data as well as gtopo30 dem data.
Detailed information on the characteristics of gtopo30 including the data. The resolution is suitable for continental or country mapping. It has a 30arc second resolution approximately 1 km, and is split into 33 tiles stored in the usgs dem file format. Gtopo30 digital elevation model dem data available from the u. Detailed information on the characteristics of gtopo30 including the data distribution format, the data sources, production methods, accuracy, and hints for users, is found in the gtopo30 readme file. Elevation data sets at different resolutions has been compiled from the gtopo30 global digital elevation model for use in making several data products. These data were by developed by the usgs eros data center in 1996 from a variety of data sources. Webgis free terrain data geographic information systems. To be removed read 30arcsecond global digital elevation. Description z,refvec gtopo30tilename reads the gtopo30 tile specified by tilename and returns the result as a regular data grid.
The gtopo30 global digital elevation model is made by the u. Distribution format for a global digital elevation model dem with 30arcsecond grid spacing. All places gis managing data questions log in to create and rate content, and to follow, bookmark, and share content with other members. This article explains how to download the global 30arcsecond. Gtopo30 is a global data set covering the full extent of. Elevations in gtopo30 are regularly spaced at 30arc seconds 1120th of a degree, which is approximately 1 kilometer at the equator. Like all good things the gtopo30 data set is divided into tiles, and by unhappy coincidence the area described above spans two tiles, so we need to do the following. Jan 20, 2020 gtopo30, completed in late 1996, was developed over a three year period through a collaborative effort led by staff at the u. Read 30arcsecond global digital elevation data gtopo30.
See the gmted2010 page for more information and download of compact data files at some standard resolutions. An alternative is to reproject the data into a system cough, utm that uses the same units for horizontal. This document describes how to download ibm infosphere datastage server, version 8. Topographic data available from the noaa national centers for environmental information ncei and collocated world data service for geophysics, boulder. A few calculations are necessary to make the file compatible with the functions in the spatial analyst extension. Using the gtopo30 global topographic data set with arcgis on. Gmted global multiresolution terrain elevation data is a global terrain dataset that is the newer version of gtopo30 dataset. Comments from users of gtopo30 are welcomed and encouraged.
Use to select a region as the spatial extent to subset data. Gtopo30 provides a new level of detail in global topographic data. Digital elevation model dem data are sampled arrays of surface elevations in raster form. Each table contains links to both a an overall quality summary, which provides a filelevel quality assessment for each data product. The gtopo30 data set is based on data derived from eight sources external link of. Gtopo30 correct projection geonet, the esri community gis. Launch arcgis a new empty map and make sure the arcgis spatial analyst and arcgis 3d analyst extensions are checked on recall from lab 6 tools extensioncheck the boxes. East and north bounds are adjusted automatically to make widthheight to be integer multiple of resolution xy. The data grid, z, is returned as an array of elevations. The srtm data covers most of the world at approximately 90m intervals but has inaccuracies, the gtopo30 and globe data covers the whole world at approximately 900m intervals and is accurate. The gtopo30 dataset provides an elevation model at a 30 arcsecond resolution for the entire global landmass. For both resolutions of canadian data, user can select data to be downloaded through the map user interface. The gtopo30 files can be converted to ascii by creating a grid, which was done in the previous step, and applying the following formula. This data was developed by the usgs eros data center in 1996 from a variety of data sources.
Get data tilesglobal land onekm base elevation project ncei. Gtopo30 is a global digital elevation model dem with a horizontal. Gtopo30 was derived from several raster and vector sources of topographic information. Previously, the best available global dem was the etopo5 data set, and its. Model gtopo30 data in arcview gis continued from page 49 usgs dem data, which is provided in ascii format.
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