Comparison of models calculating the sky view factor used for urban climate investigations

Martin Hämmerle, Tamás Gál, János Unger, Andreas Matzarakis

Research output: Contribution to journalArticle

44 Citations (Scopus)


The sky view factor (SVF) describes the surface geometry and is a commonly used and important measure in urban climate investigations whose aim is the exploration of effects of a complex urban surface on climatological processes in built-up areas. A selection of methods and models for calculating the SVF was compared. For this purpose, fish eye images were taken at several locations in the city of Szeged, southern Hungary. The fish eye images equidistantly follow linear transects to cover a range of SVF values and to analyze the reaction of the methods to a continuously changing environment. The fish eye pictures were evaluated by three methods: the method according to Steyn (Atmos-Ocean 18(3):245-258, 1980) implemented in a GIS-Script, the "Edit free sky view factor" tool of the RayMan model and BMSkyView. The SVF values at the coordinates of the fish eye pictures were calculated with three numerical models (SkyHelios, ArcView SVF extension, and SOLWEIG) with a 3D building data base as input. After comparing the results of the first run, a deviation occurs. The deviation disappears after implementing an option to include a weighting factor in some of the models.

Original languageEnglish
Pages (from-to)521-527
Number of pages7
JournalTheoretical and Applied Climatology
Issue number3
Publication statusPublished - Oct 2011


ASJC Scopus subject areas

  • Atmospheric Science

Cite this