Free Geospatial Data

February 8, 2018

This page is designed for Afghan planners. It may also be useful to any GIS user who works in a country where comprehensive governmental data is hard to find. Free, worldwide geospatial data is increasingly available from governments, universities, space missions, aid agencies, and private corporations.

Furthermore, the open-source community has maintained and improved software such as QGIS and GDAL to view, analyze, and edit this public data. We stand on the shoulders of giants.

Borders and Administrative Boundaries

GADM: Global administrative areas, in multiple vector formats (polygons).

Roads, Railroads, Urban Areas, Rivers, Lakes

Natural Earth: Both vector (line and polygon) and raster (pixel) data compiled by the North American Cartographic Information Society (NACIS). Their data is organized into three scale levels (1:10m, 1:50m, and 1:110m) and three categories: Cultural, Physical, and Raster. It is general data, but good quality. The website is easy to use and the files are generally small.

DIVA-GIS provides a variety of data, but it has not been updated since about 2011, and much of the data comes from the Digital Chart of the World, which I think is data from 2000. MapAbility also provides older, but comprehensive vector data, derived from the vmap0 dataset.

Topography

Geospatial topography is usually in “digital elevation model” (DEM) raster format. Public files are usually provided as geo-referenced TIFF (tagged-information file format) images. They can be opened in image editors, and look like gray-scale representations of altitude.

Open Topography. This website references other websites, and gives a quick analysis of what data is available for your area. Maintained by the San Diego Supercomputer Center.

One example of a site that OpenTopography refers to is the Marine Geoscience Data System (MGDS) Global Multi-Resolution Topography (GMRT) web service. For this site, you need to type in coordinates by hand. The figure below should help give a sense of the coordinate range you are looking for.

[IMAGE HERE: AF, provinces, major cities, 1-degree grid]

Lower-resolution DEMs are suitable for regional planning. High-resolution data can make your software run slowly. If you do not need very high-resolution data, consider these:

Earth2014. Resolution: 1 arc-minute, about 2km x 2km at the equator (5 arc-min also available). These are single files of the whole earth, about 445 MB. Maintained by Technische Universität München (TU Munich) and Curtin University (Perth, Australia). Documentation here.
Recommended file: Earth2014/data_1min/GMT/Earth2014.SUR2014.1min.geod.grd

SRTM30_PLUS. Resolution: 30 arc-second, about 1km x 1km at the equator. SRTM stands for NASA’s Shuttle Radar Topography Mission (2000). This data has been processed and refined over several years, and the current best version is 4.1. Maintained and updated by the Scripps Institution of Oceanography at the University of California, San Diego.

ETOPO1 (1 arc-minute resolution, or 60 pixels/degree), from the USA’s National Geophysical Data Center (NGDC), part of the National Oceanic and Atmospheric Administration (NOAA)

AirPhotos, SatPhotos, and Land Cover

USGS EarthExplorer: The United States Geological Survey provides a wide variety of data through it s EarthExplorer website.

Blue Marble: NASA provides a 21,600 pixels x 10,800 pixels composite file which is 60 pixels/degree (1 arc-minute of coverage), and is 174 MB as an uncompressed TIFF file. This is a true-color image of the earth’s surface overlaid on a shadow-cast of topography. The true-color imagery comes from the MODIS sensor on the Terra satellite.