Terrain data are extremely useful and essential for a wide range of environmental studies. At the local level, high-density LiDAR point clouds and derived high-resolution (e.g. 1m) Digital Elevation Models (DEMs) are increasingly produced. At the global level, medium-resolution (30m) open elevation data (e.g. SRTM and ASTER GDEM) are popular in the scientific community. The quality of such medium-resolution data varies quite a lot, and we have provided some illustrations at this page (link).

After checking and analysing more than half of dozen medium-resolution global elevation data sources, we have developed a more consistent global elevation mosaic (single file) at a spatial resolution of 30m. For areas with latitudes ranging from 60N to 56S, the 30m-resolution SRTM data are sourced; for higher latitudes, resampling from coarse-resolution (e.g. 60m to 250m) open elevation data is used.

It is always handy to have access to a good-quality elevation data mosaic. While its size appears large, with the new generation of geospatial software including open source libraries and tools, analysing and manipulating such data would not be as daunting as one initially thought. We can advise on this.

Some specifications of the global elevation mosaic:

Resolution: 30m
Projection: Latitude/longitude Geographic, WGS84
Image size: 1,296,000 by 648,000 pixels
Image file size: About 1,557 GB or 1.5 TB (single file on external hard drive)
Format: GeoTIFF (with BigTIFF) or any other suitable raster formats

Apart from the raw elevation data, we are also making 30m- and 15m-resolution shaded-relief basemaps in various styles at the global level. When superimposed with digital satellite and aerial images, the basemaps become more rich in information and context. We endeavour to make basemaps unique and more insightful by highlighting important terrain features, be they geomorphological or geologic.

A few samples are included below: