Op 10/12/2023 om 18:42 schreef Cousin Ricky:
> On 2023-12-10 10:13 (-4), Bald Eagle wrote:
>>
>> So, having looked into inversive geometry, stereographic projection, Mobius
>> transforms, etc. - I think I recall seeing some examples of slightly different
>> ways of projecting the sphere's surface onto a plane.
> 
> I suspect that there are an infinite number of such projections.
> 
>> Not having delved into this topic to any real extent, are there different image
>> maps that might not result in a correctly mapped sphere?
> 
> It all depends on the projection algorithms.
> 
>> Or is the main problem just the cylindrical vs uv-mapping in the scene?
> 
> In this particular case, it's just cylindrical vs uv-mapping.  The
> images were created in the equidistant cylindrical projection, so that
> is what I had to work with.
> 
>> Also just curious if the sphere got scaled to be an oblate spheroid.
> 
> The sphere is not scaled.  To account for oblateness, I'd have to know
> whether the maps were prepared with geocentric or geodedic latitudes,
> and *then* I'd have to remember how I handled the difference 30 years
> ago when I worked on USAF satellites.  And then a function would have to
> be applied to distort the image map in the north-south orientation.
> 
> My head is already starting to hurt.
> 
> 
Naively, I had never realised things were this /hairy/ at all when I 
simply applied NASA maps of Earth or planets to simple spheres....
I even more appreciate your work on this.
-- 
Thomas

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