Coalescing terrestrial laser scanning and aerial orthophotography for urban 3D modelling

Recent advances in aerial photography enabled cadastrates of several countries to proceed to the cartography of rural areas and record existing forestry, farming yards, plane fields and registered land ownerships. Efforts are being made to expand this project to urban areas as well, where the main object of interest apart from land itself are the buildings themselves. The main difficulty with buildings is that they are 3D objects and additional to their planar expansion there is also their height that is of significance as well. This paper aims to comprise planar information obtained through features´ extraction from ortho-open aerophotographs with vertical information obtained using terrestrial laser scanning to produce three dimensional models of multiple neighboring building blocks in an urban area. Results from the application of the proposed approach to the historic 1866 square in Chania, Greece, demonstrate both the capabilities and difficulties associated with such an attempt and derive useful conclusions for future advancements that can lead to valuable topographical urban three dimensional mappings.