Constructing a digital city on a web-3D platform: simultaneous and consistent generation of metadata and tile data from a multi-source raw dataset

In this study, we develop a platform that can display approximately 20 types of data via a web browser to realize a digital twin of a wider area, including a detailed reading display of block units and individual three-dimensional point cloud data (point cloud) of a city. Using actual data, we examine if the data model and visualization design correspond with the zoom level. Owing to the comparative examination of the wide-area display performance and the map representation design in a JavaScript-based open-source library, we were able to develop a platform with light architecture and an easily customizable display. Furthermore, prototyping, based on Mapbox GL JS and Deck.GL, and the display of spatiotemporal flow layers, such as background maps, point cloud data in many places, dozens of layer display types, and the General Transit Feed Specification (GTFS) allowed for the seamless transition from the local government to the wide-area display in the prefecture unit in approximately 10-20 s. It is recommended that this digital smart city platform should be standardized by other local governments, especially in areas where higher-order data visualization is yet to advance. To display this digital city in a lightweight environment, we consider the digital data situation of local governments in Japan. It is necessary to define the visualized design for each zoom level according to the characteristics of the data. We then arranged the display model of each zoom level for 20 types of urban infrastructure data related to the digital smart city by referring to the style schema of the tile form. Through these tasks, we organized the commonality and optimization of data models and formats.