The increasing complexity of infrastructures and densely built-up areas requires a proper registration of the legal status (private and public), which can only be provided to a limited extent by the existing 2D cadastral registrations. The registration of the legal status in complex 3D situations will be investigated under the header of 3D Cadastres. The Workshop on 3D Cadastres addresses developments in the following areas: - 3D Cadastre operational experiences (analysis, LADM based, learn from each other, discover gaps) - 3D Cadastre cost effective workflow for new / updated 3D parcels = 4D (part of whole chain: from planning / design / permit in 3D, to registration / use in 3D) - 3D Cadastre web-based dissemination (usability, man-machine interfaces, including mobile/AR) - Legal aspects for 3D Cadastre, best legal practises in various legislation systems - Focus on large cities, including developing countries