Abstract
The CityGML model is now the norm for smart city or digital twin city development for better planning, management, risk-related modelling and other applications. CityGML comes with five levels of detail (LoD), mainly constructed from point cloud measurements and images of several systems, resulting in a variety of accuracies and detailed models. The LoDs, also known as pre-defined multi-scale models, require large storage-memory-graphic consumption compared to single scale models. Furthermore, these multi-scales have redundancy in geometries, attributes, are costly in terms of time and workload in updating tasks, and are difficult to view in a single viewer. It is essential for data owners to engage with a suitable multi-scale spatial management solution in minimizes the drawbacks of the current implementation. The proper construction, control and management of multi-scale models are needed to encourage and expedite data sharing among data owners, agencies, stakeholders and public users for efficient information retrieval and analyses. This paper discusses the construction of the CityGML model with different LoDs using several datasets. A scale unique ID is introduced to connect all respective LoDs for cross-LoD information queries within a single viewer. The paper also highlights the benefits of intermediate outputs and limitations of the proposed solution, as well as suggestions for the future.
Highlights
Spatial scale modeling, either in 2D or 3D, aims to create abstraction objects/ models in various domains for improved understanding and decision-making in managing the real world
We introduced a term called “Scale Unique ID” to denote the construction of building model in several levels of detail (LoD) which comply with the CityGML schema and effective data management solutions to minimize current implementation drawbacks
This section discussed the final results of the CityGML LoD models migration into the PostgreSQL database as well as the capability to execute advanced spatial and attribute queries across the LoD model
Summary
Either in 2D or 3D, aims to create abstraction objects/ models in various domains for improved understanding and decision-making in managing the real world. Handling multiple LoD models in separated file-based architecture is inefficient in terms of storage, attribute information, data updating, and information query, especially if it involves visualization platforms. It limits the ability of stakeholders, agencies, and public users of their respective domains to share data (e.g. upload and download operation or using Application Programming Interface (API) of an online system). The proposed solution starts with constructing the CityGML model with various LoDs, migration to a database, and retrieval of information cross-LoDs. This paper introduces a new scale unique ID which acts as a primary key to connect different LoDs and enables cross-LoD queries within the database.
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