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Contemporary development of computer hardware and software, WebGIS and geo-web services as well as the availability of semantic 3D city models, facilitate flexible and dynamic implementation of web applications. The aim of this paper is to introduce 4D CANVAS, a web-based application for dynamic visualization of 3D geospatial data for improved decision making in smart city applications. It is based on the Cesium Virtual Globe, an open-source JavaScript library developed with HTML5 and WebGL. At first, different data formats such as JSON, GeoJSON, Cesium Markup Language (CZML) and 3D Tiles are evaluated for their suitability in 4D visualization applications. Then, an interactive Graphical User Interface (GUI) is built observing the principle of cartographic standards to view, manage, understand and explore different simulation outputs at multiple spatial (3D surface of buildings) and temporal (hourly, daily, monthly) resolutions. In this regard, multiple tools such as aggregation, data classification, etc. are developed utilizing JavaScript libraries. As a proof of concept, two energy simulations and their outputs of different spatial and temporal resolutions are demonstrated in five Asian and European cities. Finally, the 4D CANVAS is deployed both in desktop and multi-touch screens. The proposed application allows easy integration of any other geospatial simulation results, thereby helps the users from different sectors to explore them interactively in 4D.

Visualization of underground infrastructure in an interactive 3D immersive environment is extremely important for efficient management of city’s infrastructure. This paper describes different geometric modelling approaches to illustrate appropriate visualization of such data. A multimodal prototype has been developed by exploiting different algorithms to render these invisible underground objects as part of an urban model. This prototype has been integrated in an immersive geographic information system (GIS), named MultiVis, for handheld iOS and Android devices. As a part of the study, three distinct strategies have been tested; the first is based on the use of transparencies to convey a sense of depth, the second relies on an image-space superposition of “ditches” on top of the rendered frame and the third is a world-space deformation of the elevation model that exposes the underground elements. Furthermore, a comparative user experience analysis of different techniques aimed to the geometrically accurate visualisation of utility networks and other underground facilities are performed and evaluated. It includes a set of user evaluations for different parameters of these techniques, which gives us an insight on how the proposed methods affect the experience and usability for technical and non-technical users.

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This research explores the usage of freely available open-source resources for the deployment of a plug-in free web-application interface for 3D geospatial data to visualize energy related modelling and simulation results. Such plug-in free web mapping applications will be essential for future cartographic web applications as forthcoming web browsers will no longer support the usage and installation of those plug-ins used in the past. As a proof of concept, a 3D city model of the city of Karlsruhe in Germany consisting of over 87,000 buildings is used as a case study. This data set was compiled using OpenStreetMap data and outputs from energy simulation models. The CityGML format is used for data storage of this multi-domain data set. In order to ensure independence from browser plug-ins, HTML5 and freely available JavaScript libraries are used for the creation of this application. Multiple analytical cartographic and geospatial functions such as cartographic classification, attribute selection, descriptive statistics, spatial buffer analysis and the retrieval of modelling results from a PostgreSQL and PostGIS data infrastructure are implemented in this interface. This paper further discusses some case studies, future enhancement opportunities of the proposed interface and experiences gathered during the interface development process that would help other cartographers and GIScientists in developing future native 3D web mapping applications.