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The Vuel Concept: Towards a new way to manage Multiple Representations in Spatial Databases Eveline Bernier, M.Sc. Yvan Bédard, Ph.D. ISPRS / ICA Workshop Multi-Scale Representations of Spatial Data Ottawa July 7th, 2002 Presentation Outline The context : MOD and SOLAP The nature of the Multiple Representations The Vuel concept The SOLAP prototype Conclusion Map-On-Demand Maps are created upon a set of constraints defined by the user. The user can select the scale and the themes to be displayed. On the web, the map must be displayed as fast as possible (< 10 sec.). Spatial On-Line Analytical Processing (SOLAP) A visual platform built especially to support rapid and easy spatio-temporal analysis and exploration of data. No query language. Based on a multidimensional structure. Operations such as drill-down, drill-up and drillacross. SOLAP Operation Drill-Down Several Display Modes Problematic There is a need, for both applications, to display a same reality according to different points of view and differents abstraction levels. On-the-Fly generalization • not efficient enough to supports such applications Existing MR structures • don’t support all kinds of multiplicity (geometric, semantic and graphic) • and are multi-scale only. Multiplicities Geometric Multi-Scale Single-Scale View C View A View X View Y Graphic View B E View X View A View Y Semantic View B Building Cadastral Parcel View A House View X Assessment Parcel View B View Y Proposed Solution To develop a new approach that extends multiple representation concepts for added flexibility in spatial databases. This structure should support different geometric, semantic or graphic representations for the same element of the reality, according to different or similar granularities. The VUEL What it is: (View Element) an idea [Bédard et al., 2000]: influenced by multidimensional data structures; aimed at supporting spatial multidimensional applications (e.g. SOLAP). the visible part of a view. a unique combinaison of semantic, geometric and graphic occurrence relations. Graphic Semantic VUEL Geometric The Vuel Semantic Graphic VUEL Geometric Ground Reality House VUEL 1 House Building Building VUEL 2 VUEL 3 VUEL 4 The Vuel Conceptual Model Built with UML and based on a multidimensional database paradigm. The vuel is presented as a central table linking three dimensions: • semantic, geometric, graphic. A spatial database view (e.g. a map) becomes an aggregation of vuels. Implementation SOLAP Prototype Visual Basic SOLAP Interface DEMO Conclusion The VUEL concept is a flexible database view engine and represents a new solution to manage multiple representations because it supports simultaneously geometric multiplicity, semantic multiplicity and graphical multiplicity. Supports different combinations of geometry, semantic graphic semiology. and This structure allows a user to easily navigate between all the multiplicities, at the occurrence level as well as at the class level. The conceptual model can be implemented on an existing relational plateform. Future Works Continue the development of the SOLAP application based on the vuel structure; Add new functionalities, temporal aspect, other display modes, implementation on a «real» multidimensional structure, etc. Develop a web-based system that supports maps-on demand; SQL-Server (VUEL) – Geomedia WebMap – ASP. Add generalization functionalities; Based on a pattern approach. Thanks! Questions??????