Re: From Bitmap to sphere

"Przemyslaw Koprowski" <org@xxxxxxxxxxxxxxxxxxx> wrote in message
news:e61jn0$b1m$1@xxxxxxxxxxxxxxxxxxxxxx
info@xxxxxxxx wrote:
I have a bitmap that I want (or rather need ;) to project onto a
sphere. How would I go about this?
I need conversion for each pixel of the bitmap.


Unless you specify *how* you want to have this
bitmap projected, it is very unlikely that anyone
can give you a resonable answer.

To see where the problem is study for a while
what different kinds of projections of the globe
are used in kartography.

There is simply no such a beast as *the* projection
of [0,1]x[0,1] square onto S^2 sphere!

I worked it out (long ago) for triangular mapping, first entirely on
paper -- which was a first :) -- but that worked well. My trick was to use a
1x2 rectangle (instead of a 1x1). A lot of the planet maps on the 'net have
this dimension (for a good cartographic reason, I might add).
Subdividing a sphere into triangles re-maps these Mercator projections
nicely back onto the sphere. It even allows for the near-zero point at the
poles (your triangles will degenerate there).

[Jongware]


.

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