Supplementary material for: Pirowski, T., Szypuła B., 2023 "Dasymetric population mapping using building data"

This paper uses data on residential buildings from the nationwide vector database. Attribute information on buildings (location, volume, function, etc.) provides opportunities to estimate the number of residents. The recalculation of the population from the urban units into new spatial units was based on the area-weighted aggregation method. The location of buildings constituted a limiting variable, while the total square meterage (calculated as the area of the buildings and the number of their floors) constituted the binding variable. The introduction of additional binding variables related to the type of building and its location, as well as various methods of determining the square meterage per building type, resulted in the creation of a total of 19 maps of Cracow’s population. The results of the recalculation of population were related to demographic data compiled by the organisation Statistics Poland (GUS) relating to the 1x1 km grid. Comparison of the results with demographic data relating to other reference units allowed the reduction of subjective interpretation and the refining of input data conversion methods. As a result, correct methods for segmenting buildings were identified, useful optimisation criteria were selected, and the accuracy of population maps developed based on the database was calculated. For the input data, based solely on the amount of population in urban units, the calculated value of the mean absolute percentage error (MAPE) in the 1x1 km grid was 310.8%, and for the root mean square error (RMSE) was 1476 people. In the dasymetric method, directly associating the population with the volume of buildings, the errors fell to 21.9% and 632 people, respectively. Among the remaining 18 variants introducing the segmentation of buildings from the database, the best result was obtained for the variant based on minimizing the RMSE, associating the number of residents to single-family buildings (2.88 people/building) and associating the number of residents to the square footage in multi-family buildings (37.1m2/person) (MAPE=19.2%, RMSE=556 people).