We are happy to announce that the paper Modeling a 3D City Model and Its Levels of Detail as a True 4D Model, authored by Ken Arroyo Ohori, Hugo Ledoux, Filip Biljecki and Jantien Stoter, has been published in the ISPRS International Journal of Geo-Information.
The topic of the paper is investigating and developing a three-step approach to model the level of detail (LOD) as an extra geometric dimension perpendicular to the three spatial ones. The result is a true 4D model in which a single 4D object (a polychoron) represents a 3D polyhedral object (e.g., a building) at all of its LODs and a multiple-LOD 3D city model is modeled as a 4D cell complex.
The paper (open access) can be accessed here.