Online Help
System Overview
SVIQUEL is a visual query language which allows us to specify the relative
spatial position (both topology and direction) between objects using direct
manipulation of spatial query filters. The SVIQUEL sliders (S-sliders) are
complimented by an Active-Picture-for-Querying (APIQ) providing qualitative
visual representations of the quantitative query specified by the S-sliders.
This increases the utility of the system for spatial browsing and spatial
trend discovery with no particular query in mind. The tight coupling between
the quantitative S-sliders and qualitative APIQ allows the users to work
either qualitatively or quantitatively depending on his/her particular needs
and freely switch between the two while working in a continuous data
exploration mode.
System Walkthrough
In this new paradigm for spatial browsing, the users should be able to
use the following process:
- Select the two subsets of the spatial data.
- Query for spatial relationships between the two subsets.
- Review a visualization of results for spatial trends.
- Incrementally adjust spatial query filters or go ahead and select new
subsets for querying.
The system on start-up shows the main SEE window. Two menu items are provided,
File and Help. The File option provides users with options
for subset selection and SVQL query.
Subset Selection
On system start-up, the user is provided with two selection lists for the
selection of the two subsets. Each selection list contains a list of spatial
object types from which to select. In our application, House, Lake and
Park are the underlying spatial objects. The user is allowed to select
one or more items in each subset. The selected items are ORed and the results
from each subset are ANDed together. Two buttons Select All and
Select None are also provided to allow the user to select all or none of
the data items as part of the two subsets. The following figure shows a
subset selection list with House, Lake and Park.
SVIQUEL Query
Once the user has selected the two subsets, he selects the SVIQUEL Query
under the File menu.
The user could use the S-sliders to specify a quantitative relative
position spatial query. The APIQ is updated to reflect the current user query
as the user moves the S-sliders back and forth. The APIQ depicts all the
possible positions that objects in subset B occupy with respect to the objects
in subset A. The user can also use the mouse to select/de-select the
primitives of interest to him. The APIQ gets updated and so does the S-slider
settings to reflect the current user query.
The following figure shows a SVIQUEL interface with the S-sliders and APIQ.
Spatial Visualization
The system provides a map and bar visualization that gets dynamically updated
to reflect the results of the current query. The map visualization is provided
at the left bottom part of the SVIQUEL window and the bar visualization appears
in the main SEE window.
The map visualization displays the actual spatial positions of the objects
that satisfy the query. On the other hand, the bar visualization provides a
qualitative visual indication of the strengths of the spatial relationships
The following figure shows a bar visualization of the results of a spatial
query.
