UDMV14: Eurographics Workshop on Urban Data Modelling and Visualisation

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https://diglib.eg.org/handle/10.2312/7761

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Browsing UDMV14: Eurographics Workshop on Urban Data Modelling and Visualisation by Issue Date

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    Hierarchical Radiosity for Procedural Urban Environments
    (The Eurographics Association, 2014) Roure, Ferran; Besuievsky, Gonzalo; Patow, Gustavo; Gonzalo Besuievsky and Vincent Tourre
    In this paper we present a novel solution for the computation of diffuse global illumination in urban environments that takes advantage of the underlying structure of the procedural building models used for generating the city, using them to compute a realistic global illumination solution based on the well known hierarchical radiosity algorithm. As we generate the geometry procedurally, we take advantage of the generation hierarchy to be the base of the hierarchical radiosity algorithm, without using the classic quad-based subdivision scheme. This structure is used for low-frequency global illumination, being later combined with a shadow-map-like system for the highfrequency component, thus resulting in a complete global illumination solution for procedural urban environments.
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    Ground Temperature Modelling: The Case Study of Rue des Maraîchers in Geneva
    (The Eurographics Association, 2014) Upadhyay, Govinda; Kämpf, Jérôme; Scartezzini, Jean Louis; Gonzalo Besuievsky and Vincent Tourre
    This paper presents a methodology to approximate the urban heat island effect by using a PostgreSQL database and CitySim software, a simulation tool to evaluate urban energy flows. A ground temperature model has been developed for shallow depths (until 4m), which reproduces the phenomena of heat transfer into the ground on an hourly basis. This model is further used to predict the outdoor ground surface temperature, which is an indicator of the urban heat island effect. A PostgreSQL database which contains information such as the building footprints, geographical location, address, construction date, energy system etc. of the buildings was modified to include data relative to this model. A case study has been performed in a small neighbourhood, Rue des Maraîchers, in Geneva (Switzerland) in order to illustrate the usage of this tool to analyse the surface temperature of asphalted roads and green alleys. Finally, a methodology has been introduced to predict the urban heat island effect using this temperature.
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    Managing Temporal Change of Cities with CityGML
    (The Eurographics Association, 2014) Morel, Maxime; Gesquière, Gilles; Gonzalo Besuievsky and Vincent Tourre
    An increasing number of cities are developing digital models. It becomes thus necessary to take into account changes over time. Interoperability and thus the use of standards is also recommended. In this paper, we propose a new method, based on CityGML to take into account changes in the objects which compose the city. This method is efficient for any kind of changes of the city objects (semantic, geometry, topology or appearance). We then propose an extension of our method in order to consider more frequent changes as it is the case with sensors data that can be linked with part of city objects.
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    A Configurable LoD for Procedural Urban Models intended for Daylight Simulation
    (The Eurographics Association, 2014) Besuievsky, Gonzalo; Barroso, Santiago; Beckers, Benoit; Patow, Gustavo; Gonzalo Besuievsky and Vincent Tourre
    In many applications, such as in massive urban models visualization or in the study of the impact of urban simulation at different scales, models with different levels of detail are required. In this paper we propose a flexible system for configuring level of details models using Procedural Modeling aiming to generate only the geometry required for each specific need. We test our system for a solar simulation analysis at urban scale. We evaluate the solar irradiation and the Sky View Factor in order to study the impact at different scales. We show that our tool provides a way to handle the complexity of urban scale models, and specifically to study the sensitivity of the geometry.
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    Applying Level-of-detail and Perceptive Effects to 3D Urban Semantics Visualization
    (The Eurographics Association, 2014) Zhang, Fan; Tourre, Vincent; Moreau, Guillaume; Gonzalo Besuievsky and Vincent Tourre
    Urban environment consists of various types of data, both geometric ones and non-geometric ones, among which urban semantics are important sources for non-geometric data. The modelling and visualization of urban semantics is one type of information visualization (InfoVis). In both 2D and 3D environment, a lot of work has been done, which use different kinds of representation forms to illustrate knowledge and information stored in the original abstract dataset. This paper aims to apply the idea of information level-of-detail (LoD) to urban semantics visualization and a text-based semantic database is built to illustrate how the idea works. Then in the implementation process, four perceptive factors for text visualization are chosen, while we mainly test, compare and analyse text size, aiming to better aid users find new knowledge and make decisions.
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    Topological Reconstruction of Complex 3D Buildings and Automatic Extraction of Levels of Detail
    (The Eurographics Association, 2014) Diakité, Abdoulaye A.; Damiand, Guillaume; Maercke, Dirk Van; Gonzalo Besuievsky and Vincent Tourre
    This paper describes a new method allowing to retrieve the indoor and outdoor topology of a detailed 3D building model from its geometry and to extract different levels of detail (LoD) from the resulting topological description. No prior information about the initial model, except its geometric information is needed as input, and using the combinatorial maps data structure, the method recovers the topological information of the identified parts of the building. The topology is needed for most of the applications using 3D building models after the architects design it. While classical models available are mainly furnished in a Boundary Representation (B-Rep) format, we discuss how to recover the components that allow to distinguish the several parts of the building (defined as volumes) then the spatial relationships linking them.
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    Visualizing Street Orientation and Solar Radiation in Relation to Complex Topography
    (The Eurographics Association, 2014) Mohajeri, Nahid; Gudmundsson, Agust; Kämpf, Jérôme H.; Scartezzini, Jean Louis; Gonzalo Besuievsky and Vincent Tourre
    Street networks can be visualized in various ways depending on the purpose. Here we introduce (in the present context) a new technique for visualizing the orientation of street networks in relation to complex topography. The technique is tested on the city of Sheffield, England, with a current population of about 555,500 (in 2010) and a total street number of 23,500. Using digital elevation maps and unique historical datasets, we show how the street network of Sheffield has expanded in a complex topographical environment for close to three centuries, that is, since 1736. The results demonstrate how the topography has affected the spatial orientation of the evolving network. We quantify the network geometry through entropy analysis; entropy is a measure of dispersion or spreading. The results show that the orientation entropy of the network has gradually increased with time. In 1736 the network was primarily composed of orthogonal streets, and had comparatively low entropy. As the network expanded the topographical constraints have contributed to the street orientation becoming more uniform on the rose, resulting in increasing entropy. The analysis also shows that the entropy of the central part of the present network is lower than that of the outer and younger parts. The potential solar radiation for Sheffield is also calculated, visualized, and compared with the topography model and the street network density. The results show that the network density (number of streets per unit area) correlates solar radiation; high-density parts of the network tend to coincide with high-intensity solar radiation.
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    Incremental Plane-based Reconstruction and Exploration of Buildings in old Postcards
    (The Eurographics Association, 2014) Younes, Lara; Romaniuk, Barbara; Bittar, Eric; Gonzalo Besuievsky and Vincent Tourre
    We present an approach for 3D reconstruction of a city model over the time from a collection of old postcards of the city of Reims. The planar structure of the buildings façades constraints the dense reconstruction of the city. We use a feature matching technique while proposing the registration of façades in the images and there use for the reasoning about there visibility in the images. This system is semi-automatic, it requires a user control in the complicated case where no matches are found to link an image to the dataset. The image data set is sparse and the urban space evolves over time.