The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc. They expand the visualization and... Show More

The advantages of three dimensional (3D) city models can be seen in various applications including photogrammetry, urban and regional planning, computer games, etc. They expand the visualization and analysis capabilities of Geographic Information Systems on cities, and they can be developed using web standards. However, these 3D city models consume much more storage compared to two dimensional (2 D) spatial data. They involve extra geometrical and topological information together with semantic data. Without a proper spatial data clustering method and its corresponding spatial data access method, retrieving portions of and especially searching these 3D city models, will not be done optimally. Even though current developments are based on an open data model allotted by the Open Geospatial Consortium (OGC) called CityGML, its XML-based structure makes it challenging to cluster the 3D urban objects. In this research, the authors propose an opponent data constellation technique of space-filling curves (3D Hilbert curves) for 3D city model data representation. Unlike previous methods, that try to project 3D or n-dimensional data down to 2D or 3D using Principal Component Analysis (PCA) or Hilbert mappings, in this research, they extend the Hilbert space-filling curve to one higher dimension for 3D city model data implementations. The query performance was tested for single object, nearest neighbor and range search queries using a CityGML dataset of 1,000 building blocks and the results are presented in this paper. The advantages of implementing space-filling curves in 3D city modeling will improve data retrieval time by means of optimized 3D adjacency, nearest neighbor information and 3D indexing. The Hilbert mapping, which maps a sub-interval of the ([0,1]) interval to the corresponding portion of the d-dimensional Hilbert's curve, preserves the Lebesgue measure and is Lipschitz continuous. Depending on the applications, several alternatives are possible in order to cluster spatial data together in the third dimension compared to its clustering in 2 D.

The dawn of GeoWeb 2.0, the geographic extension of Web 2.0, has opened new possibilities in terms of online dissemination and sharing of geospatial contents, thus laying the foundations for a... Show More

The dawn of GeoWeb 2.0, the geographic extension of Web 2.0, has opened new possibilities in terms of online dissemination and sharing of geospatial contents, thus laying the foundations for a fruitful development of Volunteered Geographic Information (VGI) systems. The purpose of the study is to investigate the extension of VGI applications, which are quite mature in the traditional bi-dimensional framework, up to the third dimension by means of virtual globes. Inspired by the visionary idea of Digital Earth, virtual globes are changing the way people approach to geographic information on the Web. Unlike the 2D visualization typical of Geographic Information Systems (GIS), virtual globes offer multi-dimensional, fully-realistic content visualization which allows for a much richer user experience. The proposed system should couple a powerful 3D visualization with an increase of public participation thanks to a tool allowing data collecting from mobile devices (e.g. smartphones and tablets). The participative application, built using the open source NASA World Wind virtual globe, is focused on the cultural and tourism heritage of Como city, located in Northern Italy. Users can create and manage customized projects and populate a catalogue of cartographic layers which is available to the entire community. Together with historical maps and the current cartography of the city, the system is also able to manage geo-tagged data, which come from user field-surveys performed through mobile devices in order to report POIs (Points Of Interest). Users can also extend POIs information adding more textual and multimedia contexts (e.g. images, audios and videos) directly on the globe. All in all, the resulting application allows users to create and share contributions as it usually happens on social platforms, additionally providing a realistic 3D representation enhancing the expressive power of data.

The present climate and environmental policy efforts require comprehensive planning regarding the modification of the energy supply and infrastructures in cities. The strategic planning of the... Show More

The present climate and environmental policy efforts require comprehensive planning regarding the modification of the energy supply and infrastructures in cities. The strategic planning of the different measures requires a holistic approach and the combination of extensive and complex information. Within this paper, current developments in the context of the project Energy Atlas Berlin are presented. The Energy Atlas Berlin is based on the semantic information model of CityGML and provides an integrative data backbone for the common spatio-semantic representation of the city structure including energy related information of different themes. The virtual 3D city model of Berlin (mainly LOD2 building models) is used as data basis and has been enriched by information of different stakeholders and disciplines. In order to ensure the energy supply, the knowledge about the energy demands of buildings during the planning and optimization of measures is of great strategic importance. Therefore, this paper focuses on the city-wide estimation of the energy demands of buildings including heating, electricity and warm water energy in the city of Berlin using available official geobase and statistical data integrated within the Energy Atlas Berlin. It is explained in detail how the spatial and semantic properties of the 3D building models are being used to estimate these energy demands on an individual building level for the entire city.

There is a great demand in multipurpose elements design for use adaptation. This in turn requires great flexibility in design strategies, as well as a wider spectrum of space settings to achieve the... Show More

There is a great demand in multipurpose elements design for use adaptation. This in turn requires great flexibility in design strategies, as well as a wider spectrum of space settings to achieve the required environment that special activities imply. Acoustics is an essential factor influencing cognitive acts and behavior as well as on the extreme end the physical wellbeing inside a space. The complexity of this constrain is fueled up by the extended geometric dimensions of multipurpose halls, making acoustic adequateness a great concern, that could not easily be achieved for each purpose. To achieve a performance oriented acoustic environment, various parametric shaped false ceilings based on origami folded notion are simulated. These parigamic shapes are able to fold and unfold forming an oribotic structure, and changing the mutual acoustic environment according to the geometric shapes position and its changing exposed surface areas. The mobility of the facets in the parigamic surface can stretch up the range from a complete plain surface to an unfolded element where a considerable amount of absorption is added to the space. The behavior of the parigamic shapes are being modeled employing a ray tracing computer simulation package for various shapes topology. Results revealed a divergence of results that is caused by the folded facets to shorten the mean free path thus introducing more reflections and consequently quicker decay curves.