4.3 Spatia) schema (ISO 19107)
157
perimeter
The operation "perimeter" shall return the sum of the lengths of all the boundary
eomponents of this generie surfaee. Sinee perimeter, like length, is an aeeumulation
of distanee, its return value shall be in a referenee system appropriate for measuring
distanees.
perimeter = h + 12 + b + 14
Fig. 4.50. Operation perimeter
area
The area of a 2-dimensional geometrie objeet is a numerie measure of its surfaee
area (in a square unit of distanee). The operation "area" returns the area of the requested generie surfaee.
horizontalCurve
The operation "horizontaICurve" eonstruets a eurve that traverses the surfaee
horizontally.
verticalCurve
The operation "vertieaICurve" eonstruets a eurve that traverses the surfaee vertieally.
surface
The operation "surfaee" traverses the surfaee both vertieally and horizontally.
4.3.3.5 Aggregation
Arbitrary aggregations of geometrie objeets are possible. These are not assumed
to have any additional internal strueture. The aggregation of points is ealled multi
point, multi eurve, multi surfaees, and multi solids (classes GM _MultiPoint,
GM _ MultiCurve, MultiSurfaee, and GM _MultiSolid respeetively).