Shell model representation as a substitute of LoD3 for 3D modeling in CityGML

Abstract

The OGC standard for 3D city modeling is widely used in an increasing number of applications. It defines five consecutive Levels of Detail (LoD0 to LoD4 with increasing accuracy and structural complexity), in which LoD3 includes all exterior appearances and geometrical details and subsequently requires much storage space. A new LoD is introduced as shell model with the exterior shell of the LoD3 model and the opening objects like windows, doors as well as smaller façade objects are projected onto walls. In this paper, a user survey is presented. The results of this survey show that the shell model can give users almost the same visual impression as the LoD3 model. Furthermroe, algorithms are developed to extract the shell model from LoD3 model. Experiments show that this shell model can reduce up to 90% storage of the original LoD3 model. Therefore, on one hand it can be used as a substitute for a LoD3 model for the visualization on small displays. On the other hand, it can be treated as a sub-level of detail (SLoD3) in CityGML, since it retains almost the same amount of information but requires much less storage space.

3D building model simplification method considering both model mesh and building structure

“…These structures were continuously removed to simplify the model. Fan, Meng, and Jahnke (2009) and Fan, Mao, Shen, and Meng (2011) used the semantic information in the CityGML model to identify the internal and external building components. The building was simplified by deleting the internal components.…”

Quantitative and Qualitative Analysis on the Integration of Geographic Information Systems and Building Information Modeling for the Generation and Management of 3D Models

“…This format is still suitable for GIS and BIM integration because of its data interchangeability [39]. It is the most widely used international standard for storing and exchanging three-dimensional city models with semantics [23,[40][41][42] in the geospatial domain [24]. The CityGML core module defines the basic concepts and components of the data model; therefore, it is unique and must be implemented by any system.…”

“…The LoDs (from GIS) are developed in five levels of detail, from LoD0 to LoD4 (Figure 9), having different precisions and minimum dimensions, which are used to represent objects in the model of a three-dimensional city (El-Mekawy et al, 2012; Fan et al, 2011). Thus, LoD0 represents a terrain region in 2.5D; LoD1 are simple volumetric model representations, that is, "boxes"; LoD2 add the roof structure (flat or sloping) to the previous one; LoD3 present the architectural details on the exterior of the model, such as openings and wall textures; and, finally, LoD4 includes the representation of details of the interior of the model, such as the partitions and the delimitation of different spaces [41].…”

Revisiting the Concept of Level of Detail in 3d City Modelling

“…Usually, where the topic is tackled, researchers either relate to LoDs as seen from the computer graphics perspective, or assume common knowledge of the term. Meng and Forberg (2007);Fan et al (2011) detect the ambiguity that level of detail is uniformly defined as a number of milestones along the scale space when taking the scale space of 3D buildings as a linear continuum, but there are no agreed LoDs for 3D buildings because LoD frameworks are normally established according to the spatial accuracy, the semantic precision, and the complexity of buildings required for different applications.…”