Jacynthe Pouliot

Reasoning about geological space

Topological relationships between geological objects are of great interest for mining and petroleum exploration. Indeed, adjacency, inclusion and intersection are common relationships between geological objects such as faults, geological units, fractures, mineralized zones and reservoirs. However, in the context of 3D modeling, actual geometric data models used to store those objects are not designed to manage explicit topological relationships. For example, with Gocad? software, topological analyses are possible but they require a series of successive manipulations and are time consuming. This paper presents the development of a 3D topological query prototype, TQuery, compatible with Gocad? modeling platform. It allows the user to export Gocad? objects to a data storage model that regularizes the topological relationships between objects. The development of TQuery was oriented towards the use of volumetric objects that are composed of tetrahedrons. Exported data are then retrieved and used for 3D topological and spatial queries. One of the advantages of TQuery is that different types of objects can be queried at the same time without restricting the operations to voxel regions. TQuery allows the user to analyze data more quickly and efficiently and does not require a 3D modeling specialist to use it, which is particularly attractive in the context of a decision-making aid. The prototype was tested on a 3D GeoModel of a continental red-bed copper deposit in the Silurian Robitaille Formation (Transfiguration property, Quebec, Canada).

3D Cadastre in the Province of Quebec: A First Experiment for the Construction of a Volumetric Representation

The current cadastral system in the province of Quebec is a graphical one in the sense that it presents the limits and the official measures of the property on a 2D digital map. To be able to represent superimposed properties like condominium, the Quebec cadastre uses “le cadastre vertical” that is a polygon with a number that refers to an external complementary plan (PC). This plan shows vertical profile of the properties and a detail draw of each floor (private and common parts). A single PC-number could refer to hundreds of lots and plans depending on the geometric complexity of the building. The understanding of the spatial arrangement of all superimposed properties contained in the PC file is a tricky mental exercise. To help users of the cadastre vertical, a semi-automatic procedure is proposed that enables the construction of a volumetric representation from the PC image file. In this specific constraint situation, the various data processing steps are described starting with the vectorization (from image to vectors), the 3D modeling (the construction of the volumetric representation) and finally the data exchange. The ins and outs of every data processing, the time and efforts required to achieve each step are discussed, and we conclude with remarks made by the end users about potential usages of such cadastral volumetric representation.

How the ISO 19152 Land Administration Domain Model performs in the comparison of cadastral systems: A case study of condominium/co-ownership in Quebec (Canada) and Alsace Moselle (France)

Abstract This paper proposes an original approach for comparing cadastral management systems, more specifically, the conceptual modeling used to spatially represent vertical divided co-ownership (usually equivalent to the condominium). The comparison is based on the ISO 19152 Land Administration Domain Model (LADM) specification, an international standard recently adopted by ISO. The LADM comparison is applied between Quebec (Canada) and Alsace Moselle (France) condominium units. Specific attention is paid to the third geometric dimension of the spatial representation used in each jurisdiction. The study includes the creation of LADM layouts for condominium units in Quebec and Alsace Moselle and a comparative analysis. The paper discusses the advantages and limitations of using LADM layouts to undertake such comparisons and gives advices to produce similar analysis for others cadastral systems. LADM schematization certainly made the comparison between Quebec and French condominium units easier, more concise and clearer. The formal description of common set of concepts and terms such as proposed by LADM allows us to quantify the similarities and differences, and potentially move towards the “automatic” creation of a matching file between both systems. One of the main advantages is the graphical views resulting from the schematization process that permit visual comparison where both systems can now be compared side by side, class by class, attribute by attribute. The use of the LADM specification is, however, not evident and requires quite a few skills in data modeling. The LADM documentation is somewhat technical and lacking in official definition. It required time to comprehend the documentation, and some LADM classes, attributes or relationships are ambiguous and still difficult to match with both systems.

Progress and New Trends in 3D Geoinformation Sciences

The integration of the 3rd dimension in the production of spatial representation is largely recognized as a valuable approach to comprehend our reality, that is 3D. During the last decade developments in 3D Geoinformation (GI) system have made substantial progress. We are about to have a more complete spatial model and understanding of our planet in different scales. Hence, various communities and cities offer 3D landscape and 3D city models as valuable source and instrument for sustainable management of rural and urban resources. Also municipal utilities, real estate companies benefit from recent developments related to 3D applications. In order to present recent developments and to discuss future trends, academics and practitioners met at the 7th International Workshop on 3D Geoinformation. This book comprises a selection of evaluated, high quality papers that were presented at this workshop in May 2012. The topics focus explicitly on the last achievements (methods, algorithms, models, systems) with respect to 3D GeoInformation requirements. The book is aimed at decision makers and experts as well at students interested in the 3D component of geographical information science including GI engineers, computer scientists, photogrammetrists, land surveyors, urban planners, and mapping specialists.

Toward 3D spatial dynamic field simulation within GIS using kinetic Voronoi diagram and Delaunay tetrahedralization

Geographic information systems (GISs) are widely used for representation, management, and analysis of spatial data in many disciplines. In particular, geoscientists increasingly use these tools for data integration and management purposes in many environmental applications, ranging from water resources management to the study of global warming. Beyond these capabilities, geoscientists need to model and simulate three-dimensional (3D) dynamic fields and readily integrate those results with other relevant spatial information in order to have a better understanding of the environmental problems. However, GISs are very limited for the modeling and simulation of spatial fields, which are mostly 3D and dynamic. These limitations are mainly related to the existing GIS spatial data structures that are static and limited to 2D space. In order to overcome these limitations, we develop and implement a new kinetic 3D spatial data structure based on Delaunay tetrahedralization and a 3D Voronoi diagram to support a 3D dynamic field simulation within GISs. In this article, we describe in detail the different steps from discretization of a 3D continuous field to its numerical integration, based on an event-driven method. For validation of the proposed spatial data structure itself and its potential for the simulation of a dynamic field, two case studies are presented in the article. According to our observations, during the simulation process, the data structure is maintained and the 3D spatial information is managed adequately. Furthermore, the results obtained from both experiments are very satisfactory and are comparable with the results obtained from other existing methods for the simulation of the same dynamic field. To conclude, we discuss the current challenges related to the development of the 3D kinetic data structure itself and its adaptation to 3D dynamic field simulation and suggest some solutions for its improvement.

Development of a Web Geological Feature Server (WGFS) for sharing and querying of 3D objects

In order to adequately fulfil specific requirements related to spatial database integration with 3D modeling tools, this paper presents the development of a generic and open system architecture called Web Geological Feature Server (WGFS). WGFS provides direct access through Web services to 3D geological models. WGFS is based on a three-tier architecture: a client (Gocad), an application server (Apache Tomcat and Deegree) and a DBMS (MySQL). This architecture takes advantage of standard-compliant spatial applications such as WFS and GML standards stemming from OGC and spatial schema from ISO TC/211-Geographic Information. Before introducing the architecture and motivations of some geoinformatics choices, we will remind some important issues that have to be taken into account when such development is planned.

Fondement de la modélisation conceptuelle des bases de données géospatiales 3D

For the last 15 years, designing 2D databases has benefited from new or extended formalisms proposed by the GIS research community. However, three-dimensional representations have been significantly more frequent in the recent years, especially in 3D computer graphics and in 3D GIS. In spite of this fact, there exist a lot of confusion in fundamental notions and there has been insofar no proposal for solutions aimed at facilitating the conceptual modeling of 3D geospatial databases as required for GIS applications. The first difficulty met when someone wants to design a database model for 3D applications may seem bizarre but is in fact very fundamental: the very definitions of « 3 » and of « D » ! This paper proposes fundamental notions and a solution to create conceptual models of geospatial databases for 3D applications: theoretical concepts, 3D extensions for UML, integration with Perceptory spatial and spatio-temporal PVL, simple and complex cases. MOTS CLES: definitions 3D, SIG 3D, base de donnees geospatiales, modelisation conceptuelle, UML 3D, PVL 3D, Perceptory.

A Three Step Procedure to Enrich Augmented Reality Games with CityGML 3D Semantic Modeling

3D representations have been recognized as an essential component of Augmented Reality (AR) oriented applications. However, not many examples of AR-oriented applications employ structured 3D data models despite the existence of standard 3D information models like CityGML. One of the reasons for this shortcoming can be explained by lack of a semantic-based modeling method for enriching AR-oriented data models with 3D features. Therefore, a three step procedure is proposed to address this limitation as (1) back-ward engineering of an AR-oriented application to its current data model, (2) enriching the current data model with 3D features, (3) and mapping the enriched model to a standard 3D information model. A notable contribution of this work is that the procedure of data modeling has been subject to the UModelAR meta-model which has brought a complementary standpoint to the employment of 3D geospatial modeling in AR environments. Furthermore, the 3D enriched data model has been mapped to CityGML information model with CityGML Application Domain Extension (ADE) concept. To demonstrate the feasibility of this approach, an operating mobile AR-oriented game has been used for the case study.

3D Dynamic Simulation within GIS in Support of Disaster Management

Modeling and simulation of dynamic phenomena helps specialists and decision makers to better understand, analyze, and predict natural disasters to reduce the related damages. Hence, several models and simulation approaches have been developed with their own strengths and limitations. One important factor which has to be taken into account when dealing with a disaster is its dynamic behavior and its geometrical and topological representation. Geographic information systems are very well adapted for spatial data organization, visualization, querying, and analysis, and may be helpful in the context of simulation and modeling of spatial phenomena (e.g. floods). However, regarding the three dimensional and dynamic nature of spatial data related to a disaster (which changes with respect to space and time), several complexities are added to the entire process of simulation using the existing GIS.

3D Modeling for Mobile Augmented Reality in Unprepared Environment

The emergence of powerful mobile smartphones, with embedded components (camera, GPS, accelerometers, digital compass), triggered a lot of interest in the mobile augmented reality (AR) community and new AR applications relying on these devices are beginning to reach the general public. In order to achieve a rich augmentation in terms of immersion and interactions, these mobile AR applications generally require a 3D model of the real environment to provide accurate positioning or to manage occlusions. However, the availability of these 3D models based on real spatial data is limited, restraining the capacity of these applications to be used anywhere, anytime. To overcome such limits, we developed a framework dedicated to the fast and easy production of 3D models. The proposed solution has been designed for the specific context of mobile augmented reality applications in unprepared environment and tested on iPhone.