[Geowanking] The icosahedron as spatial reference

[Dirk-Willem van Gulik]

On Sun, 9 Jan 2005, Brian Grant wrote:

> I'm curious about methods for indexing triangles below the icosahedron
> that can indicate polarity and provide interoperability with lat/lon,
> among other things.

Actually the only/real reason for me was that I was making satellite
images searchable and footprints displayable in a Web Mapping Server- and
lot of them take relatively many images at the pole. If you use some sort
of lat/lon indexing scheme your 'bucket's are getting imbalanced - as the
surface of them near the pole is much smaller than near the quator.

> I have some ideas for this subdividing index and am wondering how others

In my case rather simple I fear; a triangle into 4 equal ones:

        +             +
       / \           / \
      /   \         +___+
     /     \       /\  /\
    /       \     /  \/  \
   +---------+  +----+----+

Dw.