Geoscience Reference
In-Depth Information
Then,
non-existence
relational constraints check that no additional
inter-
space
relation has been created by generalisation.
The
operation consistency
constraints affect the intersection neighbour-
hood. If the intersecting space has already been generalised, these con-
straints check that the second generalisation is not inconsistent with the
first one. For instance, if a building has been moved one way, it should not
be moved the other way round. The operation consistency constraints are
based on the previous states of the objects stored by the scheduling com-
ponent.
Finally, if consistency constraints are violated, side effects correcting
processes are triggered. Side effects correctors are monitored by consis-
tency constraints as processes are monitored by constraints. GAEL
(Gaffuri 2007), Elastic Beams (Bader et al. 2005) or Least Squares (Harrie
and Sarjakoski 2002) can be used to correct side effects (
Figure 11
) as well
as diffusion processes (Legrand et al. 2005). If no balanced solution can be
found, the component can arbitrate by choosing a solution (before or after
2
nd
generalisation) like a legislator (Ruas 2000) or by relaxing some less
important constraints like a controller (Ruas 2000).
Figure 11:
ExaPpOe Rf side effect cRrrectiRQ by Oeast squares adMustPeQt a baOaQce betweeQ
bRth geQeraOisatiRQs
5- Results
The CollaGen model is not fully implemented but some experiments were
carried out on French topographic data (1:15k reference scale) to produce a
1:50k map on a large area containing heterogeneous landscapes (shore,
city, country, mountain). A standard set of constraints and rules, extracted
