130
4 Geometry standards
(class GM_Aggregate). In every case the vector geometry of a geographie dataset
can be completely described. In every case the fundamental geometries point, curve,
surface, and solid are supported (classes GM_Point, GM_Curve, GM_Surface, and
GM_Solid).
What is the difference between primitives, complexes, and aggregates? Primitives
are the graphie elements that form the complete graphie of a geographie dataset.
Primitives exist on their own and have no geometrie relations to their neighbourhood
apart from the cornmon frame of a Coordinate Reference System. A typical map
built on primitives and perhaps showing houses, roads, and rivers is primarily designed for visual information.
Complexes (class GM_Complex) allows the introduction of certain constraints
among the graphie elements and are widely used in cadastral applications. In this
prominent example, the parcels of a region have to cover the area without allowing
any overlaps between neighbouring parcels and without leaving any gaps in between
them. The components of a complex can be both a composite curve (class
GM _ CompositeCurve) and a composite surface (class GM _ CompositeSurface). An
example of a composite curve could be the boundary around a parcel. The term
"composite" refers to the fact that a parcel usually has more than one neighbour and
lohn R. Herring, Ph.D., is American. His
scientific background is mathematics. Today
Dr. Herring does independent research and
product design for spatial database products for
the Oracle Corporation. His current work is
both "heavily theoretical and heavily practical"
in the application of the theory to spatial databases and applications.
Dr. Herring received a BA and a MA in
Mathematics from the University of Alabama
in Huntsville. He completed his Ph.D. in
Mathematics on Differential Geometry and
Topology at the Pennsylvania State University.
For the last ten years he is Adjunct Professor at
the University of Maine in Orono. Together
with his colleagues in Orono he is editor-inchief ofthe journal GeoInformatica.
Dr. Herring's involvement in standardisation began 1993 with SQLIMM. In
ISO/TC211 he has edited the project 19107 (Spatial schema). Presently he chairs
the project 19133 (Location based services tracking and navigation) and the
Harmonized Model Maintenance Group that develops an integrated model for
the whole family ofISO 19100 standards. He is engaged in ISO/TC211 because
geographie information interoperability aids in Oracle Corporation database
products for geospatial information. Dr. Herring also chairs W orking Groups at
the Open GIS Consortium.
4 Geometry standards
(class GM_Aggregate). In every case the vector geometry of a geographie dataset
can be completely described. In every case the fundamental geometries point, curve,
surface, and solid are supported (classes GM_Point, GM_Curve, GM_Surface, and
GM_Solid).
What is the difference between primitives, complexes, and aggregates? Primitives
are the graphie elements that form the complete graphie of a geographie dataset.
Primitives exist on their own and have no geometrie relations to their neighbourhood
apart from the cornmon frame of a Coordinate Reference System. A typical map
built on primitives and perhaps showing houses, roads, and rivers is primarily designed for visual information.
Complexes (class GM_Complex) allows the introduction of certain constraints
among the graphie elements and are widely used in cadastral applications. In this
prominent example, the parcels of a region have to cover the area without allowing
any overlaps between neighbouring parcels and without leaving any gaps in between
them. The components of a complex can be both a composite curve (class
GM _ CompositeCurve) and a composite surface (class GM _ CompositeSurface). An
example of a composite curve could be the boundary around a parcel. The term
"composite" refers to the fact that a parcel usually has more than one neighbour and
lohn R. Herring, Ph.D., is American. His
scientific background is mathematics. Today
Dr. Herring does independent research and
product design for spatial database products for
the Oracle Corporation. His current work is
both "heavily theoretical and heavily practical"
in the application of the theory to spatial databases and applications.
Dr. Herring received a BA and a MA in
Mathematics from the University of Alabama
in Huntsville. He completed his Ph.D. in
Mathematics on Differential Geometry and
Topology at the Pennsylvania State University.
For the last ten years he is Adjunct Professor at
the University of Maine in Orono. Together
with his colleagues in Orono he is editor-inchief ofthe journal GeoInformatica.
Dr. Herring's involvement in standardisation began 1993 with SQLIMM. In
ISO/TC211 he has edited the project 19107 (Spatial schema). Presently he chairs
the project 19133 (Location based services tracking and navigation) and the
Harmonized Model Maintenance Group that develops an integrated model for
the whole family ofISO 19100 standards. He is engaged in ISO/TC211 because
geographie information interoperability aids in Oracle Corporation database
products for geospatial information. Dr. Herring also chairs W orking Groups at
the Open GIS Consortium.