[vtkusers] marching cubes on an implicit surface

[Jérôme]

Well, actually, I don't know... You should take a look at the source code of
vtkImplicitFunctionToImageStencil to see how the stencil is built. The doc
page deals with a Threshold.. Maybe that's a complexity optimizer ?

Good luck !
Jerome

2009/7/6 Christian Walder <chwa at imm.dtu.dk>

>  Hello,
>
> Thanks for the reply! But does this involve first computing the value of
> the implicit function on a 3D grid and then running marching cubes?
>
> I should have mentioned that this is not an option as it will involve a
> computational cost which is cubic in the resolution (due to constructing the
> 3D grid), whereas a direct application of marching cubes should be more or
> less quadratic in the resolution (as the surface itself is two-dimensional,
> and only embedded in a 3D space).
>
> Christian
>
>
>
> -----Original Message-----
> From: Jérôme [mailto:jerome.velut at gmail.com <jerome.velut at gmail.com>]
> Sent: Mon 7/6/2009 3:58 PM
> To: Christian Walder
> Cc: vtkusers at vtk.org
> Subject: Re: [vtkusers] marching cubes on an implicit surface
>
> Hi,
> You may want to build such a pipeline :
> vtkImplicitFunctionToImageStencil -> vtkImageStencil -> vtkContourFilter
>
> It *should* do the trick... Yet I had never try it !
>
> Best,
>
> Jerome
>
>
> 2009/7/6 Christian Walder <chwa at imm.dtu.dk>
>
>
>         Dear All,
>
>
>         I am completely new to vtk, and I am hoping it can solve my
> problem:
>
>
>         I have an implicit surface function mapping from R^3 to R (from
> three
>         dimensions to a scalar value), and I would like to run a marching
> cubes
>         type algorithm on it, to extract a mesh which approximates the zero
>         level set of the function. In principle it should be possible to
> use
>         some marching cubes library to do this by e.g. passing a pointer to
> the
>         function which evaluates the implicit surface function, along with
>         perhaps a bounding box and resolution, etc. However, from taking a
> quick
>         look it seems that vtk can only do this for voxel data, ie for
> functions
>         which are defined numerically on a 3D grid.
>
>
>         Does anyone know if it is in fact possible to do what I want? If
> so, can
>         anyone recommend a good reference or place to start?
>
>
>         best regards,
>
>
>         Christian
>
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