Accurate and detailed elevation (height above sea level) data are critically important for many applications including construction planning (e.g. road and building construction), solar energy installations, telecommunication (e.g. tower positioning), air traffic routing and navigation, agriculture (e.g. precision farming, vineyard establishment, irrigation scheme design, drainage system planning), forestry (e.g. harvest planning, timbre volume estimation), environmental management and impact assessments (e.g. visual impact assessment of wind turbines); disaster risk mitigation (e.g. flood modelling, mudslide and avalanche predictions), as well as urban and regional planning (e.g. densification monitoring, population estimations). For more examples, please see Applications of Digital Elevation Models.
Collecting elevation data is expensive as it requires specialized equipment (e.g. LiDAR sensors mounted on aircraft) and state-of-the-art computer processing infrastructure. For most developing countries, such information is absent at suitable resolutions (detail) or available for small areas only. In South Africa, detailed (<5 m resolution) elevation data are only available for about 0.5% of the land surface area.
GeoSmart developed an autonomous procedure for extracting highly detailed (0.5-2 m resolution) DEMs from stereographic aerial photographs or satellite images. As a proof of concept, the technology was applied to freely-available aerial photography of South Africa, resulting in a highly detailed (2 m resolution) DEM, simply called "DEMSA2" (previously known as SUDEM Level 3).
A sample of the DEMSA2 can be downloaded here.
Below are some examples of data sets derived from DEMSA.
Height above mean sea level
|Vertical accuracy||50 cm|
|Format||TIF, IMG, or Geodatabase|
|Price||See pricelist below|
|Current coverage||See map below (full completion expected in 2018)|
Download the latest version of this map, by clicking here.
|Per square km (min order of 300km2 rectangular area)||R50.00*|
|Per 1:50 000 map sheet (e.g. 3318dd)||R25,000.00*|
|Per quarter degree square (e.g. 3318d)||R75,000.00*|
* Substantial discounts (up to 50%) are offered on large orders. Please enquire.