Transcript ICA Commission on Generalisation and Multiple Representation

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??????