The introduction of web based mapping facilities that use satellite imagery,
offers local people the possibility to map their environment. However, maps need to be
accurate, which is the reason why map making is assigned to professionals. In this paper,
we investigated the classification accuracy of road infrastructure from high resolution
satellite imagery of an urban area in western Kenya achieved by surveyors and
non-surveyors alike, with and without local knowledge. Those with local knowledge
classified roads with over 92% accuracy on average, irrespective of surveying background.
Professional surveyors and laymen without local knowledge achieved lower accuracies of
67.7% and 42.9% respectively. We argue that local knowledge is also likely to improve the
classification accuracy of many other attributes featured in topographic maps and thus
conclude that there is reason to consider engaging local expertise in the production and
updating of topographic maps.