Re: [Algorithms] Res: Res: Polygon from point cloud and other from triangle list?

[metanet s. <met...@ya...>]

hi,
you might also want to check out alpha shapes and non-convex hulls: 

http://www.spatialanalysisonline.com/output/html/Non-convexhulls.html
http://www.cs.wustl.edu/~pless/546/lectures/lecture22.pdf
http://cgm.cs.mcgill.ca/~godfried/teaching/projects97/belair/alpha.html

raigan


--- On Wed, 6/24/09, Jose Marin <jos...@ya...> wrote:

> From: Jose Marin <jos...@ya...>
> Subject: [Algorithms] Res: Res: Polygon from point cloud and other from triangle list?
> To: "Game Development Algorithms" <gda...@li...>
> Received: Wednesday, June 24, 2009, 3:03 PM
> 
> Thanks for the ideas, Jon!
> 
> If I find a good algorithm, I'll post it here, if someone
> is interested.
> 
> Regards
> 
> Jose
> 
> 
> 
> ----- Mensagem original ----
> De: Jon Watte <jw...@gm...>
> Para: Game Development Algorithms <gda...@li...>
> Enviadas: Quarta-feira, 24 de Junho de 2009 15:31:56
> Assunto: Re: [Algorithms] Res: Polygon from point cloud and
> other from triangle list?
> 
> Jose Marin wrote:
> > I need to find the outline polygon (may be non-convex,
> and will be on most of the times) defined by the resulting
> shape.
> >  
> 
> The problem is that "the outline polygon" is not well
> defined, if you 
> allow it to be non-convex.
> If you can define what it means to be "the outline
> polygon," that would 
> get you closer to an algorithm.
> Write down a number of cases on paper. Draw what you think
> should be the 
> resulting polygon. Try to figure out what rule you,
> yourself, use to 
> create that polygon.
> 
> For example, you can start with the polygon that consists
> of all the 
> shapes -- this is a polygon; it's just disjoint. Now, you
> probably want 
> it to be connected. That's one requirement right there. How
> would you go 
> about connecting those shapes? The answer to that question
> is not well 
> defined, either, but it's a start.
> 
> Sincerely,
> 
> jw
> 
> 
> -- 
> 
>   Revenge is the most pointless and damaging of human
> desires.
> 
> 
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