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- Shapes described with this representation seem to be far more
difficult for a person to reconstruct than with the ASSF
representation. Although the representation made it easier for a
computer program to reason about object interaction, it is not
necessarily a good representation for people to deal with (as would be
necessary in robot programming).
- Description of the relative position of objects only in terms of
boundary elements made it difficult to reason about relative motion of objects.
Most motion operations extrapolated from an element position to
produce a derived object orientation, and then used this description
for reasoning with. It may have been more appropriate to include
object-scale orientation explicitly.
- Direction is represented very imprecisely, and the relative directions
of boundary segments on opposite sides of an object may be completely
unknown, because of the cumulative effects of unknown angles around
the boundary between them.
Overall, the extended polygon boundary representation is simpler than the ASSF
representation, and it appears to offer more power for reasoning about
interaction between objects in two dimensions. The main reason for this is
that important factors in object interaction are explicit in the EPB/PDO
representation. These factors include the representation of the boundary
itself, where interaction takes place, and of the relationships between
boundary elements on different objects, which can be used to identify possible
interactions.
Next: Extensions to the Two
Up: Extended Polygon Boundary Summary
Previous: Advantages:
Alan Blackwell
2000-11-17