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3D Mapping in South Africa: Status & Usages

S Naidoo and B Mohamed
Department of Land Affairs,
Chief Directorate of Surveys and Mapping, South Africa

Three dimensional (3D) mapping has come a long way in South Africa, starting primarily with aerial photogrammetry. The photogrammetric methods have become increasingly automated and Digital Terrain Models (DTMs) are generated by stereoscopy, using overlapping aerial photographs and ground control points as input. Digital Elevation Models (DEMs) are a collection of elevation data (heights) giving a representation of the Earth's surface. South Africa is fortunate that the Chief Directorate of Surveys and Mapping (CDSM) produces 400m, 200m, and 50m DEMs for flat, mountainous and built up areas respectively (CDSM, 2007). The most effective 3D display is obtained by draping an image over the DEM. 3D mapping was, until recently, the exclusive domain of geo-information practitioners. It required expensive and highly specialised software. Today, freely available software such as Google Earth, has made 3D mapping accessible to the public and has spurned a new and huge demand for three-dimensional maps. Currently, most GIS users in South Africa are using 2D mapping but the rapidly growing interest in 3D models is increasing and rendering techniques are being developed. The use of 3D functions is particularly powerful for the creation of DEMs and 3D visualization models which are used in a very wide range of applications.

In South Africa, we can define a few distinct categories where 3D mapping is commonly used namely; commercial sector and marketing, planning and design, as a learning tool for the promotion of information and tourism as well as in mining. 3D models are effective for visualizing the locations of users, spatial distribution of the clients and market demands for specific economic activities as well as the availability of space for development. Various agencies use DEMs for Radio Frequency planning in the design and implementation of mobile telecommunication network coverage. Landscape designers make use of 3D models for their inherent aesthetic considerations. The use of 3D visualisation and mapping in architectural applications is the norm today, achieving almost photo-realism. Extensive research has been done into 3D visualization projects using 3D reconstruction of cultural heritage buildings and other cultural resources using photogrammetric techniques and laser scanning. Some mapping companies are employing 3D mapping and visualization for more intuitive maps from which tourists can benefit. Mining companies are using 3D maps for slope and site monitoring systems, and also to monitor faulty activities before, during, and after earthquakes. 3D is also being used widely in archaeology for reconstructing the spatial context of the geology and fossils. The demand for computer-based, photo-realistic, real time visualisation of 3D environments will accelerate as more agencies, municipalities and geo-information stakeholders make high quality GIS data available in South Africa.