GTOPO30 is a global raster digital elevation model (DEM) providing
terrain elevation data with a horizontal grid spacing of 30 arc
seconds (approximately 1 kilometer). GTOPO30 was derived from
several raster and vector sources of topographic information. For
easier distribution, GTOPO30 has been divided into tiles
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
GTOPO30, completed in late 1996, was developed over a three year
period through a collaborative effort led by staff at the U.S.
Geological Survey's Center for Earth Resources Observation and
Science (EROS). The following organizations participated by
contributing funding or source data: the National Aeronautics and
Space Administration (NASA), the United Nations Environment Program
and Global Resource Information Database (UNEP and GRID), the U.S.
Agency for International Development (USAID), the Instituto Nacional
de Estadistica Geografica e Informatica (INEGI) of Mexico, the
Geographical Survey Institute (GSI) of Japan, Manaaki Whenua
Landcare Research of New Zealand, and the Scientific Committee on
Antarctic Research (SCAR).