[vtkusers] strange problem while creating a binary mask

[Anja Ende]

Hi guys,

I has completely missed this point. I thought the fact that the polygon
being closed is the only requirement.

Is there a filter in VTK that will order a given set of points in the given
direction?

Cheers and thanks,
Anja

On 31/10/06, David Gobbi <dgobbi at atamai.com> wrote:
>
> Hi Anja,
>
> The vtkPolyDataToImageStencil calculates the normal of each polygon to
> find out which face of the polygon is the front (the "outside") and
> which is the back (the "inside").  The calculation of the normal depends
> on the ordering of the points.
>
> You are extruding a polyline to create the the polydata, right?
> Unfortunately, I don't whether the the front/back orientation of the
> polygons depends on the ordering of points in the original polyline...
> Dean might have more experience here.
>
> When you apply the stencil, most classes that have a SetStencil() method
> also have a ReverseStencilOn() method to set whether you want to use the
> region inside the stencil or the region outside the stencil.
>
> - David
>
>
> Anja Ende wrote:
> > Ok, I have clearly missed this part!!!
> >
> > So, the points have to be ordered in a counter clockwise fashion???
> > Why is that???
> >
> > Cheers,
> > Anja
> >
> > On 30/10/06, * Dean Inglis* <dean.inglis at sympatico.ca
> > <mailto:dean.inglis at sympatico.ca>> wrote:
> >
> >     Hi Anja,
> >
> >     is your polydata always defined such
> >     that the points forming a closed loop are
> >     ordered counter-clockwise or equivalently,
> >     always clockwise and the vtkImageStencil set
> >     accordingly?
> >
> >     Dean
> >
> >
> >
> >
> >
> > --
> > Cheers,
> >
> > Anja
> > ------------------------------------------------------------------------
> >
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>


-- 
Cheers,

Anja
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