Urban climate data remain complex to analyze regarding their spatial distribution. The co-visualization of simulated air temperature into urban models could help experts to analyze horizontal and vertical spatial distributions. We design a co-visualization framework enabling simulated air temperature data exploration, based on the graphic representation of three types of geometric proxies, and their co-visualization with a 3D urban model with various possible rendering styles. Through this framework, we aim at allowing meteorological researchers to visually analyze and interpret the relationships between simulated air temperature data and urban morphology.

Abstract:In the context of custom map design, handling more artistic and expressive tools has been identified as a carto-graphic need, in order to design stylized and expressive maps. Based on previous works on style formalization, an approach for specifying the map style has been proposed and experimented for particular use cases. A first step deals with the analysis of inspiration sources, in order to extract 'what does make the style of the source', i.e. the salient visual characteristics to be automatically reproduced (textures, spatial arrangements, linear stylization, etc.). In a second step, in order to mimic and generate those visual characteristics, existing and innovative rendering techniques have been implemented in our GIS engine, thus extending the capabilities to generate expressive renderings. Therefore, an extension of the existing cartographic pipeline has been proposed based on the following aspects: 1-extension of the symbolization specifications OGC SLD/SE in order to provide a formalism to specify and reference expressive rendering methods; 2-separate the specification of each rendering method and its parameterization, as metadata. The main contribution has been described in . In this paper, we focus firstly on the extension of the cartographic pipeline (SLD++ and metadata) and secondly on map design capabilities which have been experimented on various topographic styles: old cartographic styles (Cassini), artistic styles (watercolor, impressionism, Japanese print), hybrid topographic styles (ortho-imagery & vector data) and finally abstract and photo-realist styles for the geovisualization of costal area. The genericity and interoperability of our approach are promising and have already been tested for 3D visualization.

Projective texturing is a commonly used image based rendering technique that enables the synthesis of novel views from the blended reprojection of nearby views on a coarse geometry proxy approximating the scene. When scene geometry is inexact, aliasing artefacts occur. This introduces disturbing artefacts in applications such as street-level immersive navigation in mobile mapping imagery, since a pixel-accurate modelling of the scene geometry and all its details is most of the time out of question. The filtered blending approach applies the necessary 1D low-pass filtering on the projective texture to trade out the aliasing artefacts at the cost of some radial blurring. This paper proposes extensions of the filtered blending approach. Firstly, we introduce Integral Radial Images that enable constant time radial box filtering and show how they can be used to apply box-filtered blending in constant time independently of the amount of depth uncertainty. Secondly, we show a very efficient application of filtered blending where the scene geometry is only given by a loose depth interval prior rather than an actual geometry proxy. Thirdly, we propose a silhouette-aware extension of the box-filtered blending that not only account for uncertain depth along the viewing ray but also for uncertain silhouettes that have to be blurred as well.

La visualisation est un mode privilégié de l’interaction des utilisateurs avec l’information géographique, et sa représentation efficace est d’autant plus importante que les données sont massives et hétérogènes et que les utilisateurs et les usages sont variés. Au-delà de la visualisation de données 2D sur un écran ou une carte papier, la visualisation de données 3D pose de nouveaux défis et nécessite des outils appropriés : volume des données, multiplicité des formats, stylisation et gestion des parties visibles, modes d’interaction et de navigation... iTowns est une plateforme technologique de l’IGN qui permet de visualiser des données géographiques 3D via le Web et propose des fonctions d’interaction avancées dans un environnement métrologique. Initialement développé par les laboratoires de recherche de l’IGN comme un outil de visualisation de données images et LiDAR issues de la cartographie mobile (c’est-à-dire acquises au moyen d’un véhicule équipé de capteurs), iTowns a évolué et permet aujourd’hui de naviguer de façon immersive au sein d’un très grand volume de données 3D, et ce dans toute la gamme d’échelles, depuis l’espace jusqu’au sol. Des interfaces sont également disponibles pour la manipulation de ces données. Désormais moteur de visualisation 3D du Géoportail 1 , iTowns s’enrichit continuellement de nouvelles fonctionnalités : en sus de la visualisation en 3D du territoire pour le grand public, il permet de développer des applications Web à usage professionnel pour co-visualiser différents types de données, les annoter, procéder à des analyses, des mesures...