[Bf-funboard] Subdividing Tris into tris (XSI Style)

[Errantkid]

On 1/26/07, Arne Schmitz <arne.schmitz at gmx.net> wrote:
>
> Am Freitag, 26. Januar 2007 15:03 schrieb Carsten Wartmann:
> > Arne Schmitz wrote:
> > > Am Freitag, 26. Januar 2007 04:40 schrieb ZanQdo:
> > >> Hi, I love this feature of XSI subdivition, made a gif about it:
> > >>
> > >> http://dogfight.3developer.com/SubTris2Tris.gif
> > >>
> > >> it subdivides triangles to triangles instead of making quads and
> keeps a
> > >> very smooth shape, could this be done with blender?
> > >
> > > Can you elaborate on that? Do you mean that instead of Catmull-Clark
> > > Subdivision, blender should also offer Loop-Subdivision?
> >
> > Did you notice the image was a animated gif?
>
> No, I did not. :) But now I have seen it.
>
> > With that xsi option it was subdividing into tris along the last
> > edgeloop. However I am not sure why it should be smoother then (at least
> > not on a sphere?)
>
> Ah yes, the problem with CC on triangle surfaces is, that it generates bad
> meshes with irregular vertices in the first iteration. Also the irregular
> vertices will be kept after more iterations. CC and Loop subdivision have
> both the property of being C^2 on all regular vertices, so for smoothness
> we
> want to avoid irregular vertices. There was a paper on this topic, that
> shows
> how to combine CC and Loop and how to join them in a C^2 manner:
>
>
> http://portal.acm.org/citation.cfm?id=1037957.1037959&coll=GUIDE&dl=GUIDE&CFID=740782&CFTOKEN=25050312
>
> HTH,
>
> Arne
>

Hi, folks. I also found this paper here in case you don't have an ACM
account:

http://www.cs.rice.edu/~jwarren/papers/triquad.pdf
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