Mapping our land more clearly and colourfully
for better analysis and visualisation


Acknowledging SRTM





To easily and quickly start image analysis on the most well-known satellite imagery - Landsat?

Please try the GUI tools Spectral Transformer for Landsat-8 imagery and Sentinel-2 imagery - for rapid band combinations, image stretching and pan-sharpening with a few simple button clicks


World basemaps

global basemaps



Applications ...

GIS desktop mapping

Web mapping

Virtual exploration

Field exploration

Flight simulation

Landscape simulation

Computer games

Defense & homeland security

Global environmental changes

Natural resources

Land cover & land use changes















































Shuttle Radar Topography Mission (SRTM), flew on the Space Shuttle Endeavour launched on 11 February 2000, had successfully collected 3D measurements of the ~80% Earth's surface. The mission was a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense, and the German and Italian space agencies, and was managed by NASA’s Jet Propulsion Laboratory (JPL) for NASA's Earth Science Enterprise, Washington, D.C.

The USGS freely distributes the latest SRTM Version 2 (also known as the "finished" version) data set, which is the result of substantial editing effort by NGA. It features the following:

- Well-defined water bodies (e.g., lakes, reservoirs and major rivers) and coastlines;
- Absence of spikes and wells (single pixel errors); and
- A small percentage of elevation voids (gaps, holes or missing data) still present.

We advocate the importance and potential of this public-domain data set, and have undertaken significant post-processing to produce a seamless, highest-resolution, near-global / global elevation mosaic and a series of cartographically-designed, GIS-ready shaded relief basemaps.

1 - Spatial resolution comparison

resolution comparison


Left 1km-resolution in previous global elevation mosaics, e.g., GTOPO30, SRTM30
Right 90m-resolution in the new near-global SRTM elevation mosaic and hillshading maps
  1km to 90m resolution: 100 times more detailed!
1km to 30m resolution: 1,000 times more detailed!


2 - GIS Applications

With the near-global / global raw elevation data at hand, users (even with limited GIS background) can conveniently subset any region of interest and then perform dedicated 2D and 3D terrain modelling in GIS. A few examples are shown below:

3D: Shaded relief
Region: Mt. Fuji, Japan
3D: SRTM elevation 3D: Global elevation mosaic + Earth Land Surface 2000 satellite imagery. Region: Mt. Rainier, Washington


Are you interested in large-sized, GIS-ready, global data products and having a copy locally? Please consider the following:

  • Some business applications (e.g., real estate, 3D urban model) require very detailed imagery such as StreetView and oblique aerial photos, but for many applications such as landscape simulations and regional environmental studies, medium-resolution data from 14.25m to 90m-resolution would be sufficient.
  • Imagine you have infrastructure and platform to make another virtual world, but are seeking a low-cost solution for quality, highly-processed global imagery and terrain data.
  • Imagine the enormous expertise and resources that are needed to reproduce the similar data products. No time is to be wasted.
  • Are you thinking of boosting company-wide mapping productivity using globally consistent data sets?
  • Do your mapping applications require a global coverage?
  • Will the imagery and terrain data be used by someone with little or no geospatial experience?
  • Imagine you are interested in GIS desktop mapping and wish to make underlying imagery and elevation layers fully dynamic and integrative.
  • Imagine you do not wish to have access to or are feed up with periodic subscriptions to online imagery tiles from virtual globes such as Google Maps, Bing Maps and ArcGIS Online, due to concerns over complex licensing terms, sluggish access speed, unexpected network disconnections and lack of your own control ...


3 - Free download 1km-resolution, global SRTM30_PLUS hillshading map

Scripps Institution of Oceanography, at University of California, San Diego, has recently created a popular 1km-resolution global elevation and bathymetry data set called SRTM30_PLUS. The data can be downloaded from its website freely for non-commercial uses. Users should read SRTM30_PLUS COPYRIGHT and README files for more information.

We at GeoSage have also implemented a terrain analysis and created hillshading maps in JPEG2000 format for the SRTM30_PLUS (SRTM30_PLUS data courtesy of Joseph Becker). Interested users can download a copy of SRTM30_PLUS hillshading map below freely for non-commercial applications, with due acknowledgement.



SRTM30_PLUS hillshading map in Google Earth


SRTM30_PLUS hillshading map A

Readme file

(image size: 43,200 x 21,600 pixels; file size: 47MB; format JPEG2000)


SRTM30_PLUS hillshading map B

Readme file

(image size: 43,200 x 21,600 pixels; file size: 29.5MB; format JPEG2000)

Small sizes:
4,320 x 2,160 pixels
8,640 x 4,320 pixels

World shaded-relief basemaps in different styles and at consistent 30m-resolution (1,000 times more detailed than the above maps at 1km-resolution; image size 1,296,000 x 648,000 pixels)


Free, efficient tools for viewing large-sized JPEG2000 files:

Nowadays almost all popular GIS and remote sensing software can display JPEG2000 files easily.



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