UDMV16: Eurographics Workshop on Urban Data Modelling and Visualisation

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https://diglib.eg.org/handle/10.2312/2631130

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3D Cities Rendering and Visualisation: A Web-Based Solution
(The Eurographics Association, 2016) Haje, Noura El; Jessel, Jean-Pierre; Gaildrat, Véronique; Sanza, Cédric; Vincent Tourre and Filip Biljecki
3D cities reconstruction and visualisation have always been a challenging area. Many software have been developed for constructing, editing and visualising 3D virtual cities. These software that allow the semi-automatic generation of virtual cities whether destined for visualisation, simulation and games have largely reduced the cost and charges of manual generation and sometimes their work outstrips the geometry to reach the semantics at a higher level. However, for faster and better performance, we are focusing on the visualisation and management of real-world data and more precisely geographic data for the web. This data is written in different standards and is largely available to users and cost free. This paper proposes a user intuitive solution based on the quite recent ArcGIS software Application Programming Interface (API) and CityGML (Geography Markup Language) in order to visualise and manage a real interactive editable city.
3D Model for Solar Energy Potential on Buildings from Urban LiDAR Data
(The Eurographics Association, 2016) Bill, Andreas; Mohajeri, Nahid; Scartezzini, Jean-Louis; Vincent Tourre and Filip Biljecki
One of the most promising sustainable energies that can be considered in urban environments is solar energy. A 3D model for solar energy potential on building envelopes based on urban LiDAR data was developed in this study. The developed algorithm can be used to model solar irradiation with high spatio-temporal resolution for roof-, facade-, and ground surfaces simultaneously, while taking into account the surrounding vegetation. Global solar irradiation is obtained for regularly spaced points on building- and ground surfaces with a spatial resolution of 1m2 and a time resolution of 1 hour. The algorithm has been implemented in Matlab and results were generated for two different test areas in the city of Geneva, Switzerland. The results for these specific areas show that, even in a dense urban area, the upper parts of south-east to south-west oriented facades receive 600 to 1000 kWh/m2/year of solar input, which is suitable for active solar installations. The results also show that south oriented facades can get higher solar input during winter months than the low inclined roof surfaces. This demonstrates that, depending on the latitude, facades can have a significant impact on the solar potential of buildings in urban areas, particularly for a sustainable energy planning application.
Automated Production of Interactive 3D Temporal Geovisualizations so as to Enhance Flood Risk Awareness
(The Eurographics Association, 2016) Jacquinod, Florence; Pedrinis, Frédéric; Edert, Jérémy; Gesquière, Gilles; Vincent Tourre and Filip Biljecki
The FLOOD AR project originates from an explicitly expressed need for digital 3D temporal georeferenced models that can be largely diffused among riverside residents through computers and mobile devices, in order to support the raising of public awareness concerning flood risk along the Rhône river. This project is led by a multidisciplinary consortium of researchers from several fields who are working together to develop usable tools and models as well as recommendations regarding visual content, interfaces and context of use for those 3D models. As far as computer science is concerned, given the practical difficulties of resorting to 3D georeferenced technologies for practitioners and the current limitations of commonly used GIS data formats and tools, automatic tools allowing any interested parties to produce 3D temporal models in order to support flood risk awareness' enhancement were developed in the first phase of the project. The storage of those 3D models in an interoperable format (CityGML) ensures that those 3D temporal models are available for other purposes in relation to flood mitigation (regarding flood risk mitigation planning and public consultations or visual analysis for instance). Automating the production of 3D temporal models guarantees that those models can be produced for any territory along the Rhône river. A tool to visualize those 3D temporal models interactively will also be made available as an open source tool as part of the project.
An Automatic Comparison Approach to Detect Errors on 3D City Models
(The Eurographics Association, 2016) Gorszczyk, Benjamin; Damiand, Guillaume; Servigne, Sylvie; Diakité, Abdoulaye; Gesquière, Gilles; Vincent Tourre and Filip Biljecki
3D building models are needed in several professional domains. To provide better results, these models must be errors-free and that is why it is required to have a way to detect and to correct errors. These errors can be geometric, topological or semantic. By using a topological structure called EBM-LCC that allows to model buildings, we create a new tool that allows to detect these three type of errors in 3D city models. The solution we propose is an algorithm that compares two EBM-LCC. This algorithm can be used to compare two different models, for example acquired with two different processes, or resulting from two different acquisition campaigns. It is also an interesting tool to compare and validate algorithms. In this work, we compare an EBM-LCC loaded directly from a CityGML model with an EBM-LCC reconstructed from a soup of polygons only. Then we can use the result of this comparison to outline possible differences or to correct one of the two models by using the information of the other one. This algorithm allowed to automatically detect and correct semantic errors on several models that are currently used by professionals. This shows the interest of EBM-LCC for the city modeling domain as it helps to reach an error-free model.
City Reconstruction and Visualization from Public Data Sources
(The Eurographics Association, 2016) Menzel, J. Robert; Middelberg, Sven; Trettner, Philip; Jonas, Bastian; Kobbelt, Leif; Vincent Tourre and Filip Biljecki
We present a city reconstruction and visualization framework that integrates geometric models reconstructed with a range of different techniques. The framework generates the vast majority of buildings procedurally, which yields plausible visualizations for structurally simple buildings, e.g. residential buildings. For structurally complex landmarks, e.g. churches, a procedural approach does not achieve satisfactory visual fidelity. Thus, we also employ image-based techniques to reconstruct the latter in a more realistic, recognizable way. As the manual acquisition of data required for the procedural and image-based reconstructions is practically infeasible for whole cities, we rely on publicly available data as well as crowd sourcing projects. This enables our framework to render views from cities without any dedicated data acquisition as long as there are sufficient public data sources available. To obtain a more lively impression of a city, we also visualize dynamic features like weather conditions and traffic based on publicly available real-time data.
A Data Model for Simulation Models Relying on Spatio-temporal Urban Data
(The Eurographics Association, 2016) Langlois, Jean-Gil; Tourre, Vincent; Servières, Myriam; Gervais, B.; Gesquière, Gilles; Vincent Tourre and Filip Biljecki
To understand the complexity of modern cities and anticipate their expansion, experts from various fields conceive simulation models that can be very different. Those simulation models work with a variety of data with their own organization. Furthermore, because the urban objects are studied in the context of the evolution of a city or urban area, they carry temporal and spatial information (ADD EXAMPLES). In this paper, we present the base classes of a common data model robust and flexible enough to serve the identified use cases (EXAMPLES). We then introduce a mechanism that allows to add thematic information to those classes (AND OTHER MECHANISMS). We also present some possibilities of the use of the data model. (We end this paper by evoking the future improvements of the data model NOT MANDATORY).
From Regional LULC Model to Urban Population Density Simulation in Wallonia
(The Eurographics Association, 2016) Stephenne, Nathalie; Poelmans, Lien; Hallot, Eric; Beaumont, Benjamin; Uljee, Inge; Vincent Tourre and Filip Biljecki
Cities must develop ''Smart'' management and planning strategies to mitigate the challenges caused by urban population growth. The SmartPop project proposes a LULC model and dasymetric population density maps to Walloon policy makers for analyzing and simulating future city development and localization of citizens. In this study, the constrained Cellular Automata LULC change model developed for Flanders and the Brussels-Capital Region is applied to the Walloon Region. This paper presents the first outputs from both parts of the project. On the one hand, maps of current and simulated LULC in 2050, resulting from the the first prototype of the LULC model are presented. Secondly, the dasymetric mapping protocol developed for Flanders is calibrated with Walloon data. The resulting population density map is validated with anonymous data of the National Register of Natural Persons. This project makes use of existing tools and data to propose a common spatial planning model for Wallonia, Flanders and Brussels.
Interactive Low-Cost Wind Simulation For Cities
(The Eurographics Association, 2016) Rando, Eduard; Muñoz, Imanol; Patow, Gustavo; Vincent Tourre and Filip Biljecki
Wind is an ubiquitous phenomenon on earth, and its behavior is well studied in many fields. However, its study inside a urban landscape remains an elusive target for large areas given the high complexity of the interactions between wind and buildings. In this paper we propose a lightweight 2D wind simulation in cities that is efficient enough to run at interactive frame-rates, but also accurate enough to provide some prediction capabilities. The proposed algorithm is based on the Lattice-Boltzmann Method (LBM), which consists of a regular lattice that represents the fluid in discrete locations, and a set of equations to simulate its flow. We perform all the computations of the LBM in CUDA on graphics processors for accelerating the calculations.
Optimizing Window Shape for Daylighting: An Urban Context Approach
(The Eurographics Association, 2016) Fernández, Eduardo; Aguerre, José Pedro; Beckers, Benoit; Besuievsky, Gonzalo; Vincent Tourre and Filip Biljecki
Configuring the optimal shape and position of a building opening, such as windows or skylights, is a crucial task for daylight availability. Computing daylighting requires the use of climate-based data, which involves large data sets and a time-consuming task performed by procedures that in general are not well suited for optimization. In addition, optimal opening shapes may be strongly affected by the urban context, which is rarely taken into account or roughly approximated. In this paper we present a new opening shape optimization technique that considers the urban environment. The exterior contribution is computed through a radiosity approximation. A pinhole-based model is used to model the influence of daylight component on the interior surfaces. Our results show the importance of the exterior influence in the final optimal shapes by computing the same room at different building locations.
Point Clouds as an Efficient Multiscale Layered Spatial Representation
(The Eurographics Association, 2016) Poux, Florent; Neuville, Romain; Hallot, Pierre; Billen, Roland; Vincent Tourre and Filip Biljecki
3D point clouds describe urban shape at different scales, precisions and resolutions depending on the underlying sensors and acquisition methodology. These factors influence the quality of the data, as well as its representativity. In this paper, we propose a multi-scale workflow to obtain a better description of the captured environment through a multi-scale representative point cloud, presenting an unlimited depth and multisensory data fusion. Our method is shown over a ''smart point cloud'' data structure and based on data fusion principles retaining higher description and precision on overlapping areas. The concept is illustrated through a use case on the castle of Jehay (Belgium), where aerial LiDAR data, terrestrial laser scanner point cloud and photogrammetrybased reconstruction are combined to obtain a multi-scale data structure.
Procedural Generation of Traffic Signs
(The Eurographics Association, 2016) Taal, Fieke C.; Bidarra, Rafael; Vincent Tourre and Filip Biljecki
Procedurally-generated virtual urban worlds typically miss plausible signaling objects on the road network, unless they were manually inserted. We present a solution to the problem of procedurally populating a given urban road network with plausible traffic signs. Our tagged graph approach analyzes the road network using a rule-based reasoning mechanism that represents relevant traffic rules, in order to identify potential sign locations. Eventually, a context-based reduction step helps choose the most suitable candidates, taking into account a variety of real-world rules, and determines their actual place and orientation. We discuss the performance and validation of our approach, and conclude that its generality and flexibility make it a very convenient extension to many procedural urban environment applications.
Realistic Urban Road Network Modelling From GIS Data
(The Eurographics Association, 2016) Nguyen, Hoang Ha; Desbenoit, Brett; Daniel, Marc; Vincent Tourre and Filip Biljecki
Starting from GIS data, which are sampled and often inaccurate, this paper presents a method to reconstruct urban road surfaces respecting important geometric constraints selected from civil engineering. We propose a mathematical road surface model based upon road axes and properties. In addition, we introduce a process to produce a mesh representing the roads and the terrain so that roads and terrain match. Experiments and compelling results prove the efficiency of our framework.
UDMV 2016: Frontmatter
(Eurographics Association, 2016) Vincent Tourre; Filip Biljecki; Vincent Tourre and Filip Biljecki
Visibility of Building Exposed Surfaces for the Potential Application of Solar Panels: A Photometric Model
(The Eurographics Association, 2016) Florio, Pietro; Roecker, C.; Probst, M. C. Munari; Scartezzini, Jean-Louis; Vincent Tourre and Filip Biljecki
Urban areas are facing a growing deployment of solar technologies on the built exposed surfaces such as roofs and façades. This transformation often occurs without consideration of the needed architectural quality, which depends on the context sensitivity and on solar technologies visibility from public space. The definition of visibility is explored in this paper, and major assessment methods are described. Specifically, a Cumulative Viewshed Algorithm (CVS) is compared with a novel backward raytracing Illuminance Metric Approach (ILL). Results from a test-case in Geneva show how CVS better describes visibility from a remote perspective, while ILL is a promising and fast method for closer viewpoints, especially in urban canyon environments.
Visualization of Documented 3D Cities
(The Eurographics Association, 2016) Chagnaud, Clément; Samuel, John; Servigne, Sylvie; Gesquière, Gilles; Vincent Tourre and Filip Biljecki
Documents whether historical photographs or urban regulations are important for understanding the urban past as well as for urban planning. CityGML is an open standard used to represent 3D structure and thematic information of the cities. In this article, we briefly present how the recent extension to CityGML to represent documents has been integrated to the 4D virtual urban environment. We will then focus on different visualization techniques of documents in this environment and the various metrics used to evaluate them.

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