Le 2010-10-20 06:27, scott a écrit :
>> No, an ellips is not an unevenly scalled circle. It's close but not
>> quite the same.
>
> I always thought an ellipse was exactly the same as an unevenly scaled
> circle, what's the difference?
>
>

I remember a tread some times ago where it was discuced. Along the major 
and minor axis, there is no difference, but about midway, there is a 
very slight difference that was effectively demonstrated graphicaly 
using a scaled sphere and an ellipse made using the analytic formula for 
an isosurface.
When rendered coincidently, using distinct pigments for the scaled 
sphere and the isosurface, there was almost no coincident surfaces 
artefacts, but clearly one or the other pigment visible.

There was also a discussion about elliptical torus also showing that 
slight difference.

Anyway, the difference is prety small and, for all practical purposes, 
can be dismissed.



Alain

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