There are numerous elevation datasets with global or nearly global coverage,
but by far the most significant is SRTM.
SRTM: NASA Shuttle Radar Topography Mission
- A free dataset created by combining data from many sources, including gap-filling
SRTM, and sheets of contour maps.
- Coverage at 3 arc seconds is now global, and unlike SRTM and ASTER GDEM,
there are no serious voids or artifacts.
- In particular, he notes, with SRTM:
"..unfortunately not quite all the world was mapped. [..] Although the
0.2% of the rest of the world may not seem significant, its significance is
increased by the fact that it covers the highest summits of most of the
world's mountain ranges, including all 14 of the world's 8000m+ summits and
most of the world's 6000m+ summits. [..] More than 10 years later, NASA's
SRTM data still do not cover these areas. I began the task of filling them
from alternative sources in May 2005 and completed it in November 2012,
completing NASA's mission to map the world."
- There is even data for e.g. Norway, Sweden and the Faroe Islands where no
SRTM data is available.
- Not available yet, but... a project of the European company Astrium, begun
in 2010, with data promised in 2014, which is "intended to
be the replacement dataset for SRTM"
- 12m x 12m raster, with vertical accuracy: 2m (relative)
/ 10m (absolute)
- Global homogeneity, highly consistent dataset thanks to data collection
within 2.5 years only.
- No ground control information needed thanks to high geometric precision
- No word yet on whether it will be as free and unrestricted as SRTM.
- "Global Multi-resolution Terrain Elevation Data, 2010".
- Produced by the USGS in 2011 by combining the "current best available
global elevation data" from public sources. It is multi-resolution,
with areas at 30-, 15-, and 7.5-arc-second resolution.
- In theory, it replaces the older GTOPO30 dataset (see below).
- The dataset is delivered as tiles whose dimensions are 30° of longitude
x 20° of latitude.
- GDEM is 30m elevation dataset created by stereo-correlating the 1.3 million
scene ASTER VNIR archive, covering the Earth’s land surface between 83N and
83S latitudes, formatted in 1 x 1 degree tiles as GeoTIFF files.
- It is available from
- NASA’s GDEM
WIST site. However, the process is cumbersome, involving registration
and a complex search. In fact, as of July 2009, when i attempted to find
GDEM for two areas (Hawaii and Bolivia), both searches came back with the
name of the data file (e.g. ASTGTM_S20W065.zip) but "On-line Access:
- Japan's ASTER
GDEM site, which is easier to use.
- In a review
at the time of release, it was observed that "While
the elevation postings are ~30 m, the detail of topographic expression resolvable
in the ASTER GDEM appears to be between 100 m and 120 m... residual cloud anomalies,
a variety of pervasive artifacts.. straight lines, pits, bumps, mole runs, and
other geometric shapes.. unsightly bump/pit pairs."
- like GTOPO30, another 30 Arc Second dataset (~ 1 km)
- it is newer or more accurate than GTOPO30 in some areas
- the data is not in any format at all - just large blocks of raw binary 16-bit
values, with headers in a separate file
- has a number of nicely pre-rendered versions of the dataset
- has a handy form,
GLOBE: Select Your Own Area to specify and download a rectangular area (in
- The classis Global 30 Arc Second Elevation Data Set (around 1km resolution)
- Same resolution as DTED0, GLOBE and SRTM30 - but
older and less accurate.
- A collection of 33 files.
- The file extension is "DEM" but it's not the same format as normal
USGS HYDRO 1K Elevation Derivative Database is a version of GTOPO30 which
has been corrected using hydrology data.
Other Global Elevation
- NEXTMap World
30 (commercial data)
- Claims "Seamless, void-free coverage across the entire globe, 30-meter
ground sampling. Aggregates ASTER, SRTM and GTOPO using worldwide control
combined with Intermap’s proprietary data fusion technology."
- Commercial: "pricing is as low as $0.01 per square kilometer"
- LandInfo - Maps and International
GIS Map Products
- largest vendor of international map products
- costs can be high; e.g. $600 per 1-degree quad
- individual countries - see the Locations Page
- Converting from contour maps may be necessary
if DEMs are not available for your area of interest