Construction and Storage of 4D City Objects


The aim of this research line is to investigate the methods to construct and store multiple 3D objects in 4D space. This aims to be an alternative to the existing solution on multi-LoD objects storage, in a way that correspondences are not only kept in the city object level but also between geometric features of the objects. In addition, a continuous representation of scale or time as the 4th dimension allows for distinct LoD objects to represent different states of the 3D objects, while intermediate objects are implied by such a structure.

More specifically, this research aims to answer the following questions:

  • What kind of representation can we use in order to store and manipulate efficiently objects in 4D space?
  • What is the best way to encode city objects and semantics in such a data structure?
  • How can we identify common features between objects of different LoDs and how can they be represented in a continuous way in 4D?
  • How can we construct a complete 4D city model containing all the geo- metric and semantic information of its LoDs?
  • What is the most efficient way for permanent storage and exchange of 3D and 4D city models?

Topological reconstruction of 3D City Models

As part of this research line, we have worked on the topological reconstruction of 3D City Models from CityGML. This has been implemented in a computer software which is available as open-source in GitHub.


  • 10 Sep 2020 Presented paper: "CityJSON + web = ninja" at the 2020 3D GeoInfo Conference.
  • 24 Jun 2020 Published paper: "CityJSON in QGIS: development of an open-source plugin"
  • 14 May 2020 Invited talk '3D Gebouw Reconstructie uit BAG+AHN3' by Ravi on De Grote Geo Show.
  • 30 Apr 2020 Invited talk 'wat doet TU3D?' by Hugo on De Grote Geo Show.
  • 18 Mar 2020 Article published in the GIM International Magazine: Business Guide 2020.
  • 03 Dec 2019 Stelios Vitalis presented about versioning of 3D city models at the EuroSDR - AMS GeoBIM benchmark workshop.
  • 02 Dec 2019 Stelios Vitalis presented about CityGML support in software at the EuroSDR - AMS GeoBIM benchmark workshop.
  • 27 Sep 2019 Presented paper: "A Data Structure to Incorporate Versioning in 3D City Models" at the 2019 3D GeoInfo Conference.
  • 27 Sep 2019 Awarded Best Paper Award (Runner-up) for the paper: "A Data Structure to Incorporate Versioning in 3D City Models" at the 2019 3D GeoInfo Conference.
  • 07 Aug 2019 The first stable version of our CityJSON loader plugin for QGIS is officially accepted in the QGIS plugins' repository.
  • 02 Aug 2019 Published paper: "Incorporating Topological Representation in 3D City Models"
  • 17 Jun 2019 Published paper: "CityJSON: a compact and easy-to-use encoding of the CityGML data model."
  • 22 Jan 2019 Invited talk 'Improving the usability of 3D city models' by Hugo at the Universität Münster GI-Forum
  • 02 Oct 2018 Organised the 2018 3D GeoInfo Conference in Delft.
  • 01 Oct 2018 Presented paper: "A framework for the representation of two versions of a 3D model in 4D space" in the 2018 3D GeoInfo Conference
  • 30 Sep 2018 Organised the pre-conference workshop "Automated reconstruction of 3D City Models and using them in urban applications" for the 2018 3D GeoInfo Conference in Delft.
  • 30 Sep 2018 Developed an up-to-date 3D building service covering whole of the Netherlands 3D BAG. Published via 4TU Data Centre
  • 30 Aug 2018 Keynote at the GIScience conference in Melbourne.
  • 24 Aug 2018 Open lecture at the National University of Singapore..
  • 14 Jun 2018 Presented paper: "Topological reconstruction of 3D city models with preservation of semantics" in AGILE 2018.
  • 04 May 2018 Stelios Vitalis participated in the 3rd week of the Intensive Research Program in Discrete, Combinatorial and Computational Geometry.
  • 21 Mar 2018 Invited talk 'CityJSON---A JSON-based implementation of the CityGML data model' by Hugo at the OGC meeting (Orléans, France)
  • 15 Mar 2018 (Co)organised a successfull international symposium on Point Clouds Processing.
  • 13 Feb 2018 Stelios Vitalis successfully passed his Go/NoGo meeting after submitting his research proposal.
  • 30 Dec 2017 Jantien Stoter interviewed for ten years anniversary ERC ERC Anniversary interview.
  • 27 Nov 2017 Invited talk 'CityGML (as an encoding) is dood, lang leven CityJSON!' by Hugo at the the Geonovum Springplank (Amersfoort, the Netherlands)
  • 24 Nov 2017 Invited presentation at the GeoBIM conference in Amsterdam.
  • 02 Nov 2017 Presented our reseach subject to the NCG Symposium at the TU Delft.
  • 02 Nov 2017 Jantien Stoter nominated for personal Geo Prestige Award Professional Geo Prestige Professional Award.
  • 10 Oct 2017 Our contribution to QGIS 3D visualisation was accepted.
  • 20 Sep 2017 Presented a 3D Talk on "CityGML in GDAL introduction".
  • 22 Jul 2017 Stelios Vitalis visited FOSS4G Europe 2017 in Paris / Marne-le-Vallee in order to test the new GDAL capabilities for parsing CityGML.
  • 08 Jun 2017 Stelios Vitalis visited the "Geometry Understanding in Higher Dimensions" symposium in Paris.
  • 07 Jun 2017 Anna Labetski and Stelios Vitalis participated in the TU Delft Research Exhibit 2017.
  • 30 Mar 2017 We co-organised the EuroSDR workshop on economic value of 3D Geoinformation at ICGC Barcelona
  • 24 Mar 2017 Presented our research in the PhD symposium with the Geomatics department of TU Munchen.
  • 17 Mar 2017 We organised the technial meeting of the worldwide standardisation organisation of geographical information (OGC) in Delft (200+ participants) OGC TC Meeting Delft
  • 15 Mar 2017 We organised the Symposium 3D urban modelling with Prof Thomas H. Kolbe
  • 01 Mar 2017 Stelios Vitalis officially started working on UMnD.
  • 02 Feb 2017 The project was shown during the Research Exhibition of Delft University of Technology (175th anniversary).
  • 02 Feb 2017 Jantien (PI) participated in working visit of Dutch delegation (industry, academia and government) to London.
  • 25 Nov 2016 We organised the National 3D symposium (150+ participants)
  • 01 Sep 2016 Jantien appointed as Principal Investigator at Amsterdam Institute of Advanced Matropolitan Solutions