Digital Elevation Models (DEMs) are an important source of information in many geospatial applications where they are used in modelling, visualisation, correction of satellite imagery, etc. This is particularly the case at all stages of a mineral project from the exploration, development and mining stages. LiDAR surveys from aerial platforms are the most accurate however such surveys may be very expensive because of location charges or may not be available due to flying restrictions. In such circumstances, DEMs from Satellite Platforms are a viable option.
The following table includes the current satellites from which stereo imagery is available to produce DEMs as well as some coarse worldwide DEMs available from various sources and their accuracies.
|Source||Spatial resolution (m)||Accuracy (m)||Availability|
|SRTM||90||6-8||Land areas between latitudes
60 and -56
|GDEM (ASTER)||30||Variable||Most land areas|
|SPOT HRS||20-30||8||From archive|
|WorldDEM||12||2m vert||Most land areas|
|ALOS PRISM||5||5||From archive|
|WV-1, WV-2, GEOEYE-1||1||1||New Capture|
The SRTM DEM is an interfrommetric DEM produced from radar data collected from a Shuttle mission in 2000. The GDEM is a DEM produced from stereo imagery collected from the ASTER sensor and processed semi-automatically by ERSDAC and JPL. The initial version of this DEM was released in mid 2009 and varies from very good to un-useable depending on the area. The HRS DEM was produced by SPOT IMAGE from an instrument that is flown on the SPOT5 satellite. The individual stereo imagery is not available for purchase.
Worldwide SRTM DEM
The PRISM sensor is an instrument on the Japanese ALOS satellite which started capturing imagery in May 2006. The sensor is unique in capturing back, nadir and forward looking images for a 35 km wide swath at 2.5 m resolution. A considerable archive of triplet imagery is available and can be processed to provide good quality DEMs.
Comparison of ALOS PRISM DEM and SRTM
There are currently four Very High Resolution Satellites with ground resolution less than 1 m which can be programmed for in track stereo captures. These produce DEMs with a cell size of 1 to 2 m and accuracy in elevation of 1 to 2 m. Geoimage has found that the DEMs produced from the WorldView-2 satellite produce excellent quality DEMs.