GADM, the Database of Global Administrative Areas, is a
high-resolution
Image resolution is the detail an image holds. The term applies to digital images, film images, and other types of images. "Higher resolution" means more image detail.
Image resolution can be measured in various ways. Resolution quantifies how cl ...
database
In computing, a database is an organized collection of data stored and accessed electronically. Small databases can be stored on a file system, while large databases are hosted on computer clusters or cloud storage. The design of databases s ...
of country administrative areas, with a goal of "all countries, at all levels, at any time period." Although it is a public database, GADM has a higher
spatial resolution
In physics and geosciences, the term spatial resolution refers to distance between independent measurements, or the physical dimension that represents a pixel of the image. While in some instruments, like cameras and telescopes, spatial resolut ...
than other free databases, and also higher than commercial software such as
ArcGIS
ArcGIS is a family of client, server and online geographic information system (GIS) software developed and maintained by Esri. ArcGIS was first released in 1999 and originally was released as ARC/INFO, a command line based GIS system for manipul ...
. Those sources are commonly use to complete
data analysis with
data visualisation
Data and information visualization (data viz or info viz) is an interdisciplinary field that deals with the graphic representation of data and information. It is a particularly efficient way of communicating when the data or information is nu ...
such as
data plots,
choropleth map
A choropleth map () is a type of statistical thematic map that uses pseudocolor, i.e., color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita inc ...
, etc.
Format
The database is available in a few
export formats, including
shapefiles that are used in most common
GIS applications.
Marine Life Mapping & Visualisation
/ref> Files for use with the data analysis language R are also available.
License
GADM is not freely available for commercial use. The GADM project created the spatial data
Geographic data and information is defined in the ISO/TC 211 series of standards as data and information having an implicit or explicit association with a location relative to Earth (a geographic location or geographic position).
It is also cal ...
for many countries from spatial databases provided by national governments, NGO
A non-governmental organization (NGO) or non-governmental organisation (see spelling differences) is an organization that generally is formed independent from government. They are typically nonprofit entities, and many of them are active in h ...
, and/or from maps and lists of names available on the Internet (e.g. from Wikipedia).
See also
* Natural Earth
References
{{reflist
Web mapping
Collaborative mapping
Geographical databases