CityGML goes mobile: application of large 3D CityGML models on smartphones

Abstract

CityGML, a semantic information model for digital/virtual city models has become quite popular in various scenarios. While the data format is still actively under development, it is already supported by different software solutions, especially GIS-based desktop applications. Mobile systems on the other hand are still neglected, even though the georeferenced objects of CityGML have many application fields, for example, in the currently popular area of location-based Augmented Reality. In this paper we present an independent multi-platform CityGML viewer, its architecture and specific implementation techniques that we use to realize and optimize the process of visualizing CityGML data for use in Augmented Reality. The main focus lies in improving the implementation on mobile devices, such as smartphones, and assessing its usability and performance in comparison to web-based approaches. Due to the constrained hardware resources of smartphones, it is a particular challenge to handle complex 3D objects and large virtual worlds as provided by CityGML, not only in terms of memory and storage space, but also with respect to mobile processing units and display sizes.

3DCityDB - a 3D geodatabase solution for the management, analysis, and visualization of semantic 3D city models based on CityGML

“…While documents stores have their weakness with more complex queries including joins and spatial operations, they can be a great choice for web application backends sitting in between the RDBMS and a client. GeoRocket, 7 for example, decomposes CityGML XML files and stores the XML fragments in a (distributed) file system like Amazon S3 or MongoDB. GeoRocket is available in an Open Source and a commercial version.…”

“…Due to the Open Source nature of the 3DCityDB, researchers also report on modifying specific parts of the software. For example, Ghassoun and Löwner [15] document their adaption and usage of the 3DCityDB migration SQL script for the calculation of building volumes and Blut et al [7] describe their development of a simplified database schemawhich is inspired by the 3DCityDB schemafor using CityGML models on smartphones.…”

Cityjson + Web = Ninja

“…In the realm of 3D model visualisation there exist several frameworks to support the web distribution of common graphics formats such as COLLADA, OBJ or X3D; but direct support for CityGML is limited (Blut et al, 2019). There are several commercial software packages for CityGML visualisation, including ArcGIS (ESRI), Bentley Map (Bentley Systems) and the CityEditor (3DIS GmbH) and freeware/open source software such as FZKViewer (KIT Karlsruhe) (Blut et al, 2019).…”

“…In the realm of 3D model visualisation there exist several frameworks to support the web distribution of common graphics formats such as COLLADA, OBJ or X3D; but direct support for CityGML is limited (Blut et al, 2019). There are several commercial software packages for CityGML visualisation, including ArcGIS (ESRI), Bentley Map (Bentley Systems) and the CityEditor (3DIS GmbH) and freeware/open source software such as FZKViewer (KIT Karlsruhe) (Blut et al, 2019). Nevertheless, there is no direct support for CityGML visualisation and dissemination through the web, without the use of additional tools (such as 3DcityDB) and intermediate formats (such as GLTF) (Ledoux et al, 2019;Noardo et al, 2019).…”

Combining VR Visualization and Sonification for Immersive Exploration of Urban Noise Standards

“…Once compiled, all the resources are part of the resulting VR app. For a more dynamic approach to CityGML data, see [28], where CityGML data are still preprocessed but can then be loaded as needed.…”