4.3 Spatial schema (ISO 19107)
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Fig. 4.17. GM_Sphere
A sphere (class GM_Sphere) is a gridded surfaee given as a family of eircles
whose positions vary linearly along the axis ofthe sphere, and whose radius varies in
proportion to the eosine funetion ofthe eentral angle. The horizontal eircles resemble
lines of eonstant latitude, and the vertieal ares resemble lines of eonstant longitude.
GM_BilinearGrid
Fig. 4.18. Bilinear grid (Brozio 2003)
Abilinear grid (class GM _ BilinearGrid) is a gridded surfaee that uses line strings
as the horizontal and vertieal eurves.
143
Fig. 4.17. GM_Sphere
A sphere (class GM_Sphere) is a gridded surfaee given as a family of eircles
whose positions vary linearly along the axis ofthe sphere, and whose radius varies in
proportion to the eosine funetion ofthe eentral angle. The horizontal eircles resemble
lines of eonstant latitude, and the vertieal ares resemble lines of eonstant longitude.
GM_BilinearGrid
Fig. 4.18. Bilinear grid (Brozio 2003)
Abilinear grid (class GM _ BilinearGrid) is a gridded surfaee that uses line strings
as the horizontal and vertieal eurves.