From consistency to flexibility: A simplified database schema for the management of CityJSON 3D city models

Abstract

The use of 3D city models is now common practice; many large cities have their own digital model. Resilient and sustainable management of these models is necessary in many cases, where an application could evolve over its life cycle. The complexity of generic modelling standardization is often a limitation for a light and user-friendly usage and further developments. This paper aims to propose an alternative providing a simplified database schema implemented in a document-oriented storage. Thanks to the use of the NoSQL store, the focus is on flexibility of the data schemas and thus its clarification. In order to aim attention at the compactness in web development, CityJSON has been chosen for the encoding of the 3D city models. Finally, a full-stack application (persistent storage, consistent edition and visualization of 3D city models) has been developed to handle the simplified schema and illustrates its capabilities in two practical use cases.

From consistency to flexibility: Handling spatial information schema thanks to a middleware in a 3D city modeling context

“…Most of the time, the server and the database are closely linked and installed on the same physical machine (the architecture thus becomes a “two‐tier architecture”). A brief explanation of the usefulness of each tier provides a better understanding of the paradigm shift proposed started in previous research in which this contribution fits (Nys & Billen, 2021).…”

“…It finally results in a better usage of resources and the sharing of capabilities and information. Servicification in geographic systems is well illustrated in SOA (Bukhsh et al, 2015; Nys & Billen, 2021). A flexible architecture allows the composition and sequencing of data processing.…”

“…Without providing a complete solution compared to what relational solutions offer, the NoSQL databases offer premises of spatial data management on the web (da Costa Rainho & Bernardino, 2018). Especially in 3D city modeling, the shift from consistency to flexibility opens many possibilities (Nys & Billen, 2021). In this research, a combination between CityJSON and the NoSQL document‐oriented database provides an alternative to the traditional geodata management.…”

“…It could then be interesting to provide an alternative that concedes a loss of consistency to improve the architecture flexibility. A partial answer to this problem is to shift the use of a traditional database and move toward a NoSQL solution (Nys & Billen, 2021). This contribution is in line with this answer and proposes to make a step further from the consistency to the flexibility of databases in the scope of modeling urban environments.…”

“…As defined in the previous sections, its groundwork relies on three things: the usage of a NoSQL database that improves flexibility at the expense of some consistency, the usage of a common definition basis such as the CityGML data model, and finally a new component that filtrates information. These specifications are available thanks to the simplified database schema for the management of CityJSON 3D city models in a document‐oriented store (Nys & Billen, 2021).…”