Introduction In the past decades various activities have been conducted related to 3D Cadastres (or 3D Land Administration). The start of the international awareness of this topic was marked by the first Workshop on 3D Cadastres (sponsored by FIG commissions 3 and 7), organized by Delft University of Technology in November 2001. This was followed by virtually a session at every FIG working week and congress afterwards (stimulated by the FIG working group on this topic). Within cadastral organizations this was paralleled by on-going developments at Cadastral organizations in many countries to provide better 3D-support. The increasing complexity of infrastructures and densely built-up areas requires a proper registration of the legal status (private and public), which only can be provided to a limited extent by the existing 2D cadastral registrations. Despite all research and progress in practise, very few countries in the world can claim to have a true 3D Cadastre, the functionality is always limited in some manner; e.g. only registering of volumetric parcels in the public registers, but not included in a 3D cadastral map, or limited to a specific type of object with ad hoc semi-3D solutions; e.g. for buildings or infrastructure. At the FIG Congress in September 2022 in Warsaw is was decided to link to ISO TC211 and OGC and to add LADM (Land Administration Domain Model) activties to the scope of the working group and use a new name: Land Administration Domain Model/3D Land Administration (3DLA). This is reflecting the broader scope, now also including, marine georegulation, valuation information and spatial plan information (all needing 3D represengations of the legal spaces). The context of the FIG 3DLA Working Group is now defined by ISO 19152 (and its succesoors, now under development) Land Administration Domain Model.

Key Publications ISO and FIG publication 84 The Land Administration Domain Model - An Overview, Christiaan Lemmen, Peter van Oosterom, Abdullah Kara, and Eftychia Kalogiannin, pp.44, April 2025 (ISSN 2311-8423 / ISBN 978-87-93914-23-0 pdf). FIG publication LADM in the Classroom - Exyended version, Christiaan Lemmen, Malumbo Chipofya, Andre da Silva Mano, Abdullah Kara, Dennis Ushiña Huera, Peter van Oosterom, Eftychia Kalogianni, Eva-Maria Morscher- Unger, Javier Morales Guarin, Anthony Beck, Stephan Honer, Rohan Bennett, Paula Dijkstra, and Jaap Zevenbergen, First version, pp.166, April 2025 (ISSN 2311-8423 / ISBN 978-87-93914-24-7 pdf). FIG Publication Best Practices 3D Cadastres - Extended version, Editor: Peter van Oosterom, International Federation of Surveyors, Copenhagen, Denmark, pp. 258, March 2018 (ISBN 978-87-92853-64-6, ISSN: 2311-8423), Mongolian version (update January 2025) FIG Publication 72 Best Practices 3D Cadastres, Editor: Peter van Oosterom, International Federation of Surveyors, Copenhagen, Denmark, pp. 78, November 2018 (ISBN 978-87-92853-83-7 /ISSN 1018-6530 printed, ISBN 978-87-92853-84-4 / ISSN 2311-8423 pdf) Book Research and Development Progress in 3D Cadastral Systems, Peter van Oosterom, Efi Dimopoulou (editors), MDPI, Basel, Switzerland, pp. 302, October 2019, Printed Edition of the Special Issue Published in International Journal of Geo-Information, ISBN 978-3-03921-056-5 (Pbk); ISBN 978-3-03921-057-2 (PDF)