This poster/paper presents an updated map of the spatial growth of the Greater Accra region in Ghana, based on the analysis of Sentinel-2 imagery. Special focus is put on the gradual development process within the peri-urban areas.
The classification method, which applies texture computed from multi-size, moving windows combined with an overlay scoring technique, is presented, and its potential compared to other segmentation/classification methods within the OBIA domain is discussed.
The resulting map of urban development is compared to global datasets of urban extent (e.g. Global Urban Footprint) as well as classification results obtained from high-resolution image analysis of smaller regions. The pace and type of urban development in Accra between 1985 and 2017 is analyzed based on additional data from a previous study where similar techniques were applied on Landsat-TM imagery.
Finally, the missing link between formal definitions of “urban” and the definitions implicitly defined by an applied RS method is discussed, including the specific challenges of classifying peri-urban areas characterized by a slow, gradual development process where building foundations are often laid years ahead of completions.