Tor Olav Kristensen wrote:
> 
> But as this shape is symmetric around both
> its x and z axes (as Anton Sherwood mentioned
> too), there should be infinite gradients at
> the opposite pole as well.
> 
> But I have not experienced any problems at
> that pole yet.

Well, there's no guarantee that insufficient max_gradient leads to
artefacts.  

To avoid such problems you could cut off the spirals at some distance to
the poles, it would probably not be very visible and should solve the
problem.

Christoph 

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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Alf Peake wrote:
> 
> "Tor Olav Kristensen" <tor### [at] onlineno> wrote in message
> news:3C54A942.617AD2B5@online.no...
> [snip]
> > Attached are two images that shows
> > the defect in the shape.
> >
> > I find the "tongue" that appears in the _s2
> > image quite mysterious.
> >
> >
> > Tor Olav
> 
> Perhaps this defect is only on the inner surfaces so the upper pole
> looks OK from outside?

Alf, the defect is visible on the outside too.

I have actually turned the shape upside down
so that the defect should be less visible.
(I.e. in the shadows inside.)


Tor Olav

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"Tor Olav Kristensen" <tor### [at] hotmailcom> wrote in message
news:3C565CA8.BF44B3C6@hotmail.com...
>
> Alf Peake wrote:
> >
> > Perhaps this defect is only on the inner surfaces so the upper
pole
> > looks OK from outside?
>
> Alf, the defect is visible on the outside too.
>

Sorry. My error. I understood you only had a problem with the one
pole.

Alf

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> Anton Sherwood wrote:
> > In an equiangular spiral (reverse Mercator projection of oblique
> > parallels) . . .

Tor Olav Kristensen wrote:
> I don't remember what reverse Mercator projection is,

I meant inverse: from the plane back to the sphere.


-- 
Anton Sherwood, http://www.ogre.nu/blog/blog.htm

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