4.4 Simple Features (ISO 19125-1)
159
A topological complex (class TP _ Complex) is a complete network of topological
elements (node, edge, face, solid). A topological complex is used to describe that
two or more topological networks are disjunct. If they are disjunct then more than
one topological complex exists.
Two topological complexes may be overlayed without being linked. This may occur if a dataset has two or more thematic layers with different topologies.
4.4 Simple Features (ISO 19125-1)
The ISO 19125-1 covers 2-dimensional geometries with linear interpolation between vertices. The simple features model consists of the root class Geometry and its
subclasses Point, Curve, Surface, and GeometryCollection. The class GeometryCollection has the subclasses MultiPoint, MultiCurve, and MultiSurface.
The class Geometry is the equivalent to the class GM_Object in ISO 19107. The
class GeometryCollection is the equivalent to the class GM_Aggregate in ISO
19107. The model ofISO 19125-1 does not include complexes, a third dimension,
non-linear curves, or topology.
The simple features gained some acceptance in web mapping applications because
the amount of required data is much less than in the case of ISO 19107. It is expected that in the future, sophisticated applications like cadastre and cartography will
tend to use the ISO 19107 and the ISO 19136 (Geography Markup Language).
I Geometry I
1
I
I
I
I Point I I Curve I I Surface I
I GeometryColiection I
Ln
2 .. n
61
~
I
I
1..nJ
LineString I I Polygon I I MultiSurface I I MultiCurve I I MuniPoint I
lf
d
Ln
I I
I
I
I Line
II LinearRing I
I MultiPolygon I I MuniLineString I
?
I
Fig. 4.53. Hierarchy of geometry of8imple Features (18054 2000)