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Acquisition of 3D regular prismatic models in urban environments from DSM and orthoimages
Published in João Manuel, R. S. Tavares, R. M. Natal Jorge, Computational Modelling of Objects Represented in Images, 2018
João Ferreira, Alexandre Bernardino
In this paper we address the problem of automatic generation of 3D building models in urban areas. Several cities around the world have built virtual models of certain parts of their territory. These virtual models are important for many purposes, e.g urban modelling, telecommunications for transmitter placement, environmental planning, simulation etc. However, the large majority of the models are obtained by manual methods, requiring many man-hours of work for introducing data which makes the creation and maintenance of such models too costly and time consuming. Therefore there is a great deal of effort put in the research for automatic or semi-automatic tools for the acquisition, validation and update of cadastral data in urban areas. Classically the main input data for the production of 3D city models were aerial images, terrestrial images, map data, and surveying data. In the last years LIDAR (LIght Detection And Ranging) has become a very attractive alternative for the acquisition of 3D information since this technique directly provides a high density of 3D points. However, the obtained maps are usually smoothed and irregular, and should be complemented with other sources of information. Several works have proposed the use of aerial images to complement the LIDAR maps and present methods to combine their information toward 3D building reconstruction [3,4]. Our work fits in the same approach but the main problem addressed here is the acquisition of regular shapes for buildings’outlines. This is important in order to obtain succinct representations of buildings, allowing light storage cost and fast manipulation in visualization systems.
Flood damage cost estimation in 3D based on an indicator modelling framework
Published in Geomatics, Natural Hazards and Risk, 2020
Mostafa Elfouly, Anna Labetski
Virtual 3D city models provide details about cities and have data integrating a variety of different types of geoinformation and georeferenced urban data, which can be utilized in multiple domains such as urban planning and disaster management. These interdisciplinary domains are interconnected, so that a change in one of the domains may have an impact on one or more of the others. Additionally, virtual 3D city models have proven to be an effective tool in visualizing different application areas that facilitate the decision-making process. Hence, these models can act as an information hub assisting decision-makers, executives and politicians in exploring urban data, conducting research studies, applying analysis and feasibility studies to a specific domain in a city model, and measuring its impact on other interdisciplinary domains (Döllner et al. 2006). Nevertheless, a considerable amount of contributions to such models is pure graphical representations neglecting the semantic and topological aspects of the city (Gröger and Plümer 2012). Therefore, these models can solely be used for visualization with no further thematic or geospatial analysis being applied (Kolbe et al. 2008).
CityGML goes mobile: application of large 3D CityGML models on smartphones
Published in International Journal of Digital Earth, 2019
Christoph Blut, Timothy Blut, Jörg Blankenbach
Often virtual 3D city models are used for a general overview of large-scale environments or in areas such as urban planning, -management and -simulation. Some examples for analyses tasks are solar potential analyses, shadow analyses and disaster analyses. Biljecki et al. (2015) present a state-of-the art review for the use of 3D city models with around 30 use cases and more than 100 applications which underlines the increasing importance of 3D city models. While the majority of virtual 3D city models was purely graphical in the past and prevented more sophisticated applications, the growing popularity of semantic information models in recent years has created new opportunities. For example in the AEC industry Building Information Modeling (BIM) is becoming more and more important. With the Industry Foundation Classes (IFC) a semantic data model for the description and exchange of building data in the context of BIM already exists. One of the most influential models in geographic information science is City Geographic Markup Language (CityGML) which is an XML-encoding schema based on Geography Markup Language (GML) for storing and exchanging virtual 3D urban objects and their semantic- and topological information. It uses the ISO 19107 standard (Herring 2001) and a number of other ISO 191xx standards. Geometries are defined using Boundary Representation (B-Rep) which uses collections of observable surfaces (boundaries) to model a solid. CityGML’s module-based structure and Level of Detail (LOD) system ranging from LOD0 to LOD4 allow for problem-specific modeling. While the mandatory core module contains basic definitions, the extension modules, like the building or appearance module, add specific thematic information. The LOD system allows modeling objects in different granularities (Kolbe 2008; Schall et al. 2011; Gröger et al. 2012).
Calculating solar irradiance without shading geometry: a point cloud-based method
Published in Journal of Building Performance Simulation, 2021
Á. Bognár, R.C.G.M. Loonen, J.L.M. Hensen
3D city models can be used for representing the features of cities and landscapes, such as buildings, bridges, tunnels and transportation objects (McGlinn et al. 2019; Reinhart and Davila 2016). Worldwide coverage of 3D city models is hard to assess, due to the scattered nature of databases but it appears that their availability is increasing, especially for larger cities. Some municipalities offer their 3D city models for free (Gemeente Eindhoven 2011; SWEB 2019; tudelft3d 2021) and paid services are also available (ArcGIS 2019; CGTrader 2020).