The new digital orthometric elevation model of Kilimanjaro

Kibo, the highest of three peaks of Kilimanjaro, has not benefited from a medium to large scape topographic mapping in about 50 years. The rapidly changing topography associated with the glacier retreat and the fact that the slopes of Kibo attract about 40,000 climbers each year thus justify the need to develop a new topographic survey of this outstanding landmark, designated a UNESCO World Heritage Site in 1987. In this context, the application of the photogrammetric principles to the latest generation of very high resolution space-borne optical sensors (VHRS) offers new surveying opportunities by enabling the topographic mapping of remote and hardly accessible areas at large scale with unprecedented spatial resolution. This paper illustrates the potential of a space-borne photogrammetric survey technique by reporting on the last effort to map the topography of Kibo from GeoEye-1 stereo imagery, which has led to the creation of a new 50cm resolution Digital Elevation Model (DEM), namely KILISoSDEM2012. Furthermore, this new model is combined with the refined local geoid model KILI2008 generated from gravimetric observations captured by the international team that completed the last survey of the orthometric height of Kibo in October 2008. This paper shows that the new digital orthometric elevation model exhibits a 35% and 25% improvement in planimetric and elevation accuracy, respectively, compared to the specifications of GeoEye-1 Precision products.