Analysis of Data Sources and Mapping Techniques for Generating Topographic Base Map in Sub Saharan Africa: Case of Malawi

Abstract

Topographic maps that are being used in Malawi today are out of date. Accurate, up-to-date, reliable, accessible, consistent and reusable spatial data is required to produce Geoinformation that support the nation with development planning and decision making. Aerial Photogrammetry has been the most reliable used technology for creating and updating topographic maps. However, the method is expensive and requires highly skilled personnel such that it has been difficult for Malawi to maintain its use due to limited resources. Today high resolution satellite imageries are recommended as cost effective data source for topographic mapping. This paper presented here, evaluates the economically and technically viable mapping data sources, their processing procedures and mapping techniques for the generation of topographic base maps for Malawi at low cost. The results have shown that most countries in sub Saharan Africa are still accustomed to aerial Photogrammetry and commercial software though some have started using satellite data. The study has established that using SPOT-5 in combination with existing digital layers, Global map layers and STRM30 DEM would contribute to low cost data sources. Furthermore, use of computers with on screen digitising and use of open source software such as grass, would further reduce the cost in updating the 1:50,000 map scale as opposed to creation of new series at 1:25,000 map scale.