Topographic Mapping from Space for Arid and Semi-Arid Lands in Northern Kenya Akira Hirano Institute of History and Anthropology University of Tsukuba Japan Abstract This paper demonstrates how the use of the ASTER stereo image data can effectively contribute to updating the outdated topographic maps with minimal ground survey work in the arid and semi-arid terrain in northern Kenya. Six full scenes of ASTER stereo data each covering 60 km by 60 km were captured in August 2003 while the author performed a control survey with a global positioning system (GPS) unit on the ground. Existing but very scarce geodetic network information was supplied by the Survey of Kenya, the federal mapping agency in order to supplement the controls. Automated stereo image matching techniques were used to generate the digital elevation models (DEMs). The use of the DEMs enabled the author to update 3 topographic maps in the study area at scales 1:100,000 covering the eastern edge of the Chalbi desert and much of the Kaisut desert in Marsabit District. The multispectral ASTER image data were then orthorectified using the DEMs. Not only being able to provide the high-resolution DEMs with 30 m post spacing, the author also could map the newly developed road network and emerging towns which never appeared on the outdated topographic maps. Results indicate that topographic mapping using the ASTER stereo image data coupled with cost-efficient DEM generation algorithm requiring very little survey work prove viable in many developing countries where such geospatial data in digital format are lacking.