Automatic Façade Segmentation for Thermal Retrofit

In this paper we present an automated method to derive highly detailed 3D vector models of modern building façades from terrestrial laser scanning data. The developed procedure can be divided into two main steps: firstly the main elements constituting the façade are identified by means of a segmentation process, then the 3D vector model is generated including some priors on architectural scenes. The identification of main façade elements is based on random sampling and detection of planar elements including topology information in the process to reduce underand over-segmentation problems. Finally, the prevalence of straight lines and orthogonal intersections in the vector model generation phase is exploited to set additional constraints to enforce automated modeling. Contemporary a further classification is performed, enriching the data with semantics by means of a classification tree. The main application field for these vector models is the design of external insulation thermal retrofit. In particular, in this paper we present a possible application for energy efficiency evaluation of buildings by mean of Infrared Thermography data overlaid to the façade model.