user interface of a Spatial OLAP tool provides unique capabilities
to explore spatial data in an intuitive and interactive way. The capability
of linking or synchronizing several views of the same information in a
context of interactive exploration of data brings new possibilities to benefit
from current research in geovisualization.
visualization functions of an ideal SOLAP technology will be presented here: various display types, display synchronization, graphical
symbology, and interactive legends. Using these visualization
functions improves the access and analysis of spatio-temporal data
for non-technical users.
major part of the information of this page is from Rivest, S. et al.
 and Proulx, M.-J. & Bédard, Y. .
Various Display Types (maps,
tables, statistical diagrams)
tool supports tabular views and various types of diagrams (horizontal
and vertical bar charts, pie charts, point charts, line charts, area
charts, etc). Various types of maps can also be built, according to
the selections conducted on the different dimensions. Simple
maps and multimaps are common. Complex thematic maps and maps with superimposed
diagrams are more specialized and allow for the representation of many
dimensions on a map or many measures on a
map or both. To produce advanced maps instantaneously without SQL
operation, built-in rules must exist inside the application.
maps show many geometric elements that reflect a multiple
selection on a single spatial dimension.
reflect the concept of small multiples (i.e. a series of
maps, for example a different map per year) introduced by ,
based on the concept of collections by Bertin, .
Multimaps are usually used to show a temporal
evolution of a phenomenon.
with superimposed diagrams are
maps with small histograms or pie charts superimposed on the geometric
elements of the spatial dimension (ex. the different
regions). This cartographic representation is the result of
multiple selections on many dimensions.
thematic maps are composed of superimposed visual variables
(ex. color, pattern, shape of symbols), one per selected measure.
This particular example represents the combinaison of
two different measures on the same map, one being represented by colors and the other by patterns.
Synchronisation of operations in the different displays
SOLAP tool must allow for the synchronization
of operations from one display to another. It is important
that a selection in one display be effective for all
synchronization allows the user to visualize the same information,
but from a different perspective: a table for a detailed view of a
phenomenon, a diagram for rapid comparisons and a map for the effective
visualization of spatial trends or correlations. Temporal comparisons
are usually analyzed through diagrams, but the SOLAP tool also offers
the possibility to show several maps (called multimaps), diagrams
and tables for different epochs, or for different members of the other
dimensions, and even to browse rapidly through them to simulate dynamic
mapping. A SOLAP operation executed on one display can be, if this
type of synchronization is activated by the user, reflected immediately
and automatically in all the other displays in the same collection
(a collection being a set of linked displays that are synchronized
Graphical Semiology Management
(ex. classification types, colors)
symbology that is used to represent the different measures in the
various types of display can be defined by the administrator of
the system. A SOLAP tool must offer a flexible graphical
symbology manager that allows for the definition of different types of
data categorization, different types of thematic maps, and the
use of various visual variables. The end-users can also
create their own personal symbologies to be applied within their
own analysis sessions.
doing so may lead to potential collisions of graphical symbology
rules since the same rules do not always apply
to maps, pie charts, bar charts, tables, etc. It is then necessary
to keep a visual homogeneity serving as a link from one display
to the other and from one navigation operation to the other.
even more necessary since the nature of the different types of display
(maps, diagrams and tables) affect the quantity and the nature
of the information that may be represented by each one.
On a map,
a limited number of themes can be represented in order for the map
to be visualized as one image and remain readable. There are possible
conflicts between the displays and it then becomes necessary to define
priorities in the use of visual variables. A
graphical rules manager must be implemented into a SOLAP tool to
minimize the potential collisions and to easily create multimaps,
complex thematic maps and maps with superimposed diagrams respecting state of the art rules.
The synchronization of the graphical symbology
from one display to another cognitively facilitates the identification
and the interpretation of the data. Using the same symbology in all
the displays, it becomes easier to spot and highlight relevant information.
of the benefits of using maps is to use contextual information
to help users to locate themselves. This contextual
information is essential to the analysis in many situations.
Different types of information about the area surrounding the studied phenomenon are often as
important in constructing knowledge as the phenomenon itself. Within
a map display, it is possible to add different types of data (ex. road network,
hydrography, administrative limits, aerial photographies) in the background of the map
to achieve this goal. A SOLAP tool must thus allow to display
contextual data in addition to the spatial data being used for the thematic representation.
Interactive legend (allowing drill operations)
 worked at defining elements of interactivity that
could be incorporated into the legends of the different displays in
a SOLAP interface. The interactive legend can be seen as a graphical
view specific to the semantics of the analyzed data. This way, and because
SOLAP navigation is allowed in all views (or displays) of data, it is
also interesting to define navigation capabilities within the legend
to remain consistent throughout the user interface. The interactive
legend proposes a new type of SOLAP
operation: the classification drill operation that is a drill (down
or up) applied on the data classification used to represent measures
in the different displays. This operation allows for the visualization
of different levels of details of the data classification.
Bertin, J., 1967. Sémiologie graphique: les diagrammes, les réseaux, les
cartes. Mouton, Paris.
Pastor, J., 2004. Conception d'une légende interactive et forable pour
le SOLAP. Unpublished M.Sc. Thesis, Geomatics Sciences Department, Université Laval. http://www.theses.ulaval.ca/2004/21994/21994.pdf.
Accessed October 12, 2005.
Rivest, S., Bédard, Y., Marchand, P., 2001. Towards better support for
spatial decision-making: defining the characteristics of Spatial On-Line
Analytical Processing (SOLAP). Geomatica, the Journal of the Canadian
Institute of Geomatics 55 (4), pp. 539–555.
Rivest, S., Y. Bédard, M.-J. Proulx, M. Nadeau, F. Hubert & J. Pastor,
2005, SOLAP: Merging Business Intelligence with Geospatial Technology
for Interactive Spatio-Temporal Exploration and Analysis of Data, Journal
of International Society for Photogrammetry and Remote Sensing (ISPRS)
"Advances in spatio-temporal analysis and representation", 60 (1), pp. 17-33.
Tufte, E.R., 1983. The Visual Display of Quantitative Information. Graphics
Proulx, M.-J., Y. Bédard, 2008, Fundamental Characteristics of Spatial
OLAP Technologies as Selection Criteria, Location Intelligence 2008, April
29, Santa Clara, CA, USA