Geoscience Reference
In-Depth Information
to retain as much information as possible while the other modifies this in-
formation by displacing or deleting objects in order to clarify the map. As
a result, it introduced Galanda (2003)'s method for evaluating different
constraints. For legibility constraints and shape constraints, agents calcu-
late how much they obey the tolerance. System calculates the amount of
violation and chooses a set of actions which has minimum violation.
Constraints do not have the same importance. Safety constraint is the
strongest while shape preservation of terrain morphology is the weakest.
An action which does not respect safety will be automatically rejected by
the evaluation. Second, actions are ranked according to the legibility con-
straint. An action that ensures legibility is always preferred to one which
does not. Violation is defined by a value which represents the amount of
displacement to be done on the lines to correct the conflict. Actions which
satisfy the first two constraints are ranked according to the amount of
information preserved. This is evaluated by measuring the deformation on
the lines and the features.
Agent
Constraint
Evaluation
Line agent
(Safety) Isobath has been moved toward
greater depth
Reject if violated
(Legibility) Minimum distance between
two segments is ε
1
.
Minimum distance >= ε
1
: 0
Minimum distance < ε
1
: ε
1
- Minimum
distance
(Legibility) Minimum distance between
two lines is ε
1
.
Area >= ε
2
: 0
Area < ε
2
: ε
2
- Area
(Legibility) Minimum area of closed
isobath is ε
2
.
Area >= ε
2
: 0
Area < ε
2
: ε
2
- Area
(Preservation) The distortion of line
cannot be changed too much
Σ DistP
(Preservation) The deletion of line.
Area of deletion
Feature agent
(Safety)
(Legibility) Minimum distance between
two regions is ε
1
.
Minimum distance >= ε
1
: 0
Minimum distance < ε
1
: ε
1
- Minimum
distance
(Legibility) Minimum area of region is ε
3
.
Area >= ε
3
: 0
Area < ε
3
: ε
3
- Area
(Preservation) The slope of region can-
not be changed too much
Area between two isobaths - original
area between two isobaths
Table 6:
Evaluation of constraint
