A multi-agent System Approach for Featuredriven Generalization of isobathymetric Line - Advances in Cartography and GIScience - page 490

In table 6, ε 1 -ε 3 are given tolerances. DistP is the distance between original
point and displaced point. Σ DistP is the sum of DistP of all points on line.
For line aggregation, the change of line calculates the distortion changing
of original line and displaced line. As figure 8 shows, the P1 is original
line, P2 is displaced line which needs to merge with Q. It calculates the Σ
DistP for all modified points.
Figure 8 : Distortion of line for aggregation
If an agent performs a selective omission, points are removed and no dis-
tortion can be calculated. Instead, the preservation value is its area. If a
segment is removed from an isobath, no preservation violation can be
evaluated for the segment but the violation can be evaluated at the feature
level.
In feature level, preservation is evaluated by measuring the area difference
between consecutive lines of different elevations in order to estimate if the
overall shape and slope is preserved. Figure 9 shows the computation
method. For example, the difference between original area from 10m iso-
bath to 30m isobath and area after line modification are calculated.