131
OPERATOR
Translation
Scaling/rotation
Intersection
Number of points
Point of closest proximity
Overlaps?
Overlaps to left?
Overlaps to right?
Distance between
Left of?
Is below?
Is right of?
Is above?
Intersect or overlaps
Is horizontal?
Is perpendicular?
Length or circumference
Is vertical?
Is parallel?
Contained or on
Center of
Same as
Table 13 - The POSTGRES geometric operators
REFERENCES
AA.VV., 1994, International School for determination and
use of the geoid - Lecture Notes International Geoid
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Biagi L., Brovelli M.A. , Salemi G., 1998, Tecniche GIS
per la gestione e rappresentazione dei geoidi, Atti della II
conferenze nazionale ASITA, Novembre 1998, pp. 317-
322.
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Data Management with GIS and DBMS Techniques,
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Burroghs P. A. , 1986, Principles of Geographic
Information Systems for land resources assesment,
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Survey, n. 12, Oxford, Uk:Clarendon Press.
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Programmer’s Manual, Baylor University GRASS
Research Group.
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voi. 2, pp. 251-267;
FUNCTION
DESCRIPTION
box(point,point)
Convert point to box
Area(box)
Area of box
Isopen(path)
TRUE if this is an
open path
Isclose(path)
TRUE if this is a
closed path
Circle(point,float8)
Convert to circle
Polygon
(npts, circle)
Convert to polygon
with Npts points
center(circle)
Center of object
radius(circle)
Radius of circle
area(circle)
Area of the circle
Diameter(circle)
Diameter of the circle
Table 14 - The POSTGRES geometric functions
Jones C., 1997, Geographical Information System and
Computer Cartography, Addison Wesley Longman
Limited, Essex, England.
Laurini R. and Thomson D. , 1992, Fundamental of
Spatial Information Systems, The Apic Series,San Diego,
Ca.
Pennywitt K.E., Barrett P.J., Ray M.M., 1992, GRASS-to-
DBMS interfacing : a survey of current research effort with
recommendations for future GRASS enhancements,
Report of the Project no. A-9110-000, Computer Science
and Information Technology Laboratory Georgia Tech
Research Institute.
Stonebraker M .R. and Rowe L. A., 1986, the Design of
POSTGRES, Proc.ACM-AM-SIGMOD Conf. On
Management of Data Int. Conf.on the Mgt. Of Data.
Stonebraker M. Anton J. And Hanson E., 1987,
Extending a Database System with procedures, ACM
TODS, September,!987.
USACERL, 1993, GRASS 4.1 User’s Reference Manual,
Champaign, Illinois, United States Army Corps of
Engineers Construction Engineering Research
Laboratories.
Yu A. and Chen J„ 1995, The POSTGRES95 User
Manual, Regent of the University of California.