Direction is an important spatial relationship that is used in many fields such as geographic information systems(GIS) and image interpretation. It is also frequently used as a selection condition in spatial queries. Previous work has modeled direction as a relationship predicate between spatial objects. Conversely, in this paper, we model direction as a new kind of spatial object using the concepts of vectors, points and angles. The basic approach is to model direction as a unit vector. Given an ordered pair (p1,p2) of spatial points, one can define a direction, which can take the values of North, Northwest, 3 o'clock, etc. to represent the corresponding qualitative directional predicates on (p1,p2) in previous work. Direction objects can also have quantitative operations such as direction-composition and direction-reverse. This novel view of direction has several obvious advantages: First, it allows us to define the orientation of spatial objects; Second, a richer set of predicates and operators on direction and orientation can be defined; Third, new spatial data types such as oriented spatial objects and unbounded spatial objects can be defined. Finally, the object view of direction makes it easy to do direction reasoning, which is useful in spatial query processing and optimization.
|Original language||English (US)|
|Title of host publication||Proceedings of the 6th ACM International Symposium on Advances in Geographic Information Systems, GIS 1998|
|Publisher||Association for Computing Machinery|
|Number of pages||7|
|State||Published - Nov 1 1998|
|Event||6th ACM International Symposium on Advances in Geographic Information Systems, GIS 1998 - Washington, United States|
Duration: Nov 2 1998 → Nov 7 1998
|Name||GIS: Proceedings of the ACM International Symposium on Advances in Geographic Information Systems|
|Other||6th ACM International Symposium on Advances in Geographic Information Systems, GIS 1998|
|Period||11/2/98 → 11/7/98|
Bibliographical noteFunding Information:
1This -work is sponsored in part by the Army High Performance Computing Research Center under the auspices of the Department of the .kw, AmY Research Laboratory ~oper’ati~re asreemmt n~ber DAAI%04-9S-2-0003/contract number DA.AH04-95-GOO08, the content of whkb does not necessarily reflect the position or the policy of the government, and no official endorsement should be inferred. This work was afso supported in part by NSF grant #9631539.
This -work is sponsored in part by the Army High Performance Computing Research Center under the auspices of the Department of the Army, Army Research Laboratory co-operative agreement number DAAH0495-2-0003/contract number DAAH0495-GOC)08, the content of which does not necessarily reflect the position or the policy of the government, and no official endorsement should be inkred. This -work was also supported in part by NSF grant #9631539 Thanks to Dr. Sanjay Chawla for technical commentary and to Christiame McCarthy for helping to improve the readabd-ity of the paper.
© 1998 ACM.
- Oriented spatial object
- Unbounded object