[
CogSci Summaries home |
UP |
email
]
http://www.jimdavies.org/summaries/
Guesgen, H. W. (1989). Spatial reasoning based on Allen's temporal
logic. International Computer Science Institute technical
report. TR-89-049. 1947 Center St, Suite 600, Berkeley, CA.
@TechReport{,
author = {Hans Werner Guesgen},
title = {Spatial reasoning based on Allen's temporal logic},
institution = {International Computer Science Institute},
year = {1989},
OPTnumber = {TR-89-049},
OPTaddress = {1947 Center St, Suite 600, Berkeley, CA},
}
Author of the summary: Jim Davies, 2003, jim@jimdavies.org
Cite this paper for:
- Each quantitative relation can be uniquely mapped to a qualitative
one, while in general there are in infinite number of quantitative
relations that correspond to a qualitative one. [7]
This work presents a cognitive model for qualitative spatial reasoning
based on temporal reasoning suggested by J. F. Allen (1983).
Constraints:
- represent imprecise relationships (e.g. "I'm sitting in
the railway station")
- can handle uncertainty (e.g. you don't know the spatial
relationship between two objects)
- Granularity depends on context (e.g. the distances
referred to in "the moon rises over a field" and "a bridge
over water" are different.)
Ontology of relations between two objects (each has a converse,
forming 8 relations) one-dimensionally:
- a is left of b
- a is attached to b
- a is overlaping b
- a is inside of b
The above ontology is inspired by Allen's relational ontology of 13
time relations between two intervals. [3] Certain relations are not
captured by this (e.g. Jim is very far away from Jill) but the
discussion will be limited to these 8 for clearness in this
paper. [4]
It's reprensented with circular nodes (for objects) and rectangular
labels (for relations). Spatial reasoning, on this count, is
modifying the labels and inserting new rectangles.
Reasoning steps [6]:
- compute composition of spatial relations
- use constraint satisfaction to remove inconsistencies
Consider that there are rectangles between every pair of entities,
each with each relation in them. reasoning, then, is culling the
inconsistent ones. A transitivity table in the paper defines
constraints that must hold in a network of spatial relations (again,
similar to Allen's work).
Moving on two 2 and 3d
"Each quantitative relation can be uniquely mapped to a qualitative
one, while in general there are in infinite number of quantitative
relations that correspond to a qualitative one." [7]
To get to three dimensions, one can simply use three relations per
pair of objects, each with respect to the x, y, and z axis. [10] The
disadvantage is that certain ambiguities cannot be expressed tightly
enough. Solving this problem by using sets of tuples improves it on
this count, at the cost of a cubic disimprovement to the algorithm
efficiency.
Summary author's notes:
- The third constraint (granularity) is related to viewing
things at multiple levels of abstraction.
- This notion of spatial reasoning does not include adding
objects to the image, which makes it limited for problem solving.
Back to the Cognitive Science Summaries homepage
Cognitive Science Summaries Webmaster:
JimDavies
(jim@jimdavies.org)
Last modified: Tue May 13 10:28:57 EDT 2003