Bittner, JiriWonka, PeterWimmer, MichaelKavita Bala and Philip Dutre2014-01-272014-01-2720053-905673-23-11727-3463https://doi.org/10.2312/EGWR/EGSR05/223-230We present a fast exact from-region visibility algorithm for 2.5D urban scenes. The algorithm uses a subdivision of line space for identifying visibility interactions in a 2D footprint of the scene. Visibility in the remaining vertical dimension is resolved by testing for the existence of lines stabbing sequences of virtual portals. Our results show that exact analytic from-region visibility in urban scenes can be computed at times comparable or even superior to recent conservative methods.Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism I.3.5 [Computer Graphics]: Computational Geometry and Object Modeling