GTOPO30 is a global digital elevation model (DEM) with a horizontal grid spacing of 30 arc-seconds (approximately 1 kilometer). It was derived from several raster and vector sources of topographic information which include Digital Terrain Elevation Data, Digital Chart of the World, USGS Digital Elevation Models, Army Map Service Maps, International Map of the World, Peru Map, New Zealand DEM, and the Antarctic Digital Database, and may be viewed here. Note that, while GTOPO30 is a truly global data set, spanning from pole to pole, SRTM30 may be considered a more accurate data set between approximately 60° north and south latitude, due to its single source and the fact that the data was collected over a single 11-day period.

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 EROS Data Center (EDC). The following organizations participated by contributing funding or source data: the National Aeronautics and Space Administration (NASA), the United Nations Environment Programme/Global Resource Information Database (UNEP/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).