Talk:Geodesic grid

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tell me how you really feel[edit]

Geodesic grids have been developed by subdividing a sphere to developing a global tiling (tessellation) based on a geographic coordinates (longitude/latitude) where a rectilinear cell is defined as the intersection of a longitude and latitude line.

Does anyone understand this sentence? —Tamfang (talk) 22:42, 25 June 2010 (UTC)

Yes it means one method of partitioning a sphere (assuming Earth) is using rectilinear cells defined at the intersection of geographic coordinates. One would take as a straight forward example, the intersection of all latitudes +90 and -90 with all longitude +180 -180, the centre of each rectilinear cell. Of course that works okay for most central latitudes, but significant distortion occurs toward the poles where ultimately the squares become triangles. The preference is to retain the area of each cell while maintaining the shape - impossible with squares. —Preceding unsigned comment added by (talk) 23:00, 5 October 2010 (UTC)

This line seems mathematically incorrect: By splitting each edge into s line segments of length a1/s, and by projection of the intermediate points back onto the sphere,[3][4] each triangle is split into s2 smaller triangles, with associated viewing angles (lamba)/s. I assume the author means splitting the edge of interior icosahedron, but in that case the subtended angles will not be the same. Segments closer to the end points subtend a smaller angle and those in the middle of the segment larger because the edge is perpendicular to the sphere normal in the middle and not in the edges. — Preceding unsigned comment added by (talk) 22:47, 22 October 2013 (UTC)