Well, actually, I don't know... You should take a look at the source code of <font><font size="2">vtkImplicitFunctionToImageStencil to see how the stencil is built. The doc page </font></font>deals with a Threshold.. Maybe that's a complexity optimizer ?<br>
<br>Good luck !<br>Jerome<br><br><div class="gmail_quote">2009/7/6 Christian Walder <span dir="ltr"><<a href="mailto:chwa@imm.dtu.dk">chwa@imm.dtu.dk</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div>
<p><font size="2">Hello,<br>
<br>
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?<br>
<br>
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).<br>
<font color="#888888">
<br>
Christian</font><div><div></div><div class="h5"><br>
<br>
<br>
-----Original Message-----<br>
From: Jérôme [<a href="mailto:jerome.velut@gmail.com" target="_blank">mailto:jerome.velut@gmail.com</a>]<br>
Sent: Mon 7/6/2009 3:58 PM<br>
To: Christian Walder<br>
Cc: <a href="mailto:vtkusers@vtk.org" target="_blank">vtkusers@vtk.org</a><br>
Subject: Re: [vtkusers] marching cubes on an implicit surface<br>
<br>
Hi,<br>
You may want to build such a pipeline :<br>
vtkImplicitFunctionToImageStencil -> vtkImageStencil -> vtkContourFilter<br>
<br>
It *should* do the trick... Yet I had never try it !<br>
<br>
Best,<br>
<br>
Jerome<br>
<br>
<br>
2009/7/6 Christian Walder <<a href="mailto:chwa@imm.dtu.dk" target="_blank">chwa@imm.dtu.dk</a>><br>
<br>
<br>
Dear All,<br>
<br>
<br>
I am completely new to vtk, and I am hoping it can solve my problem:<br>
<br>
<br>
I have an implicit surface function mapping from R^3 to R (from three<br>
dimensions to a scalar value), and I would like to run a marching cubes<br>
type algorithm on it, to extract a mesh which approximates the zero<br>
level set of the function. In principle it should be possible to use<br>
some marching cubes library to do this by e.g. passing a pointer to the<br>
function which evaluates the implicit surface function, along with<br>
perhaps a bounding box and resolution, etc. However, from taking a quick<br>
look it seems that vtk can only do this for voxel data, ie for functions<br>
which are defined numerically on a 3D grid.<br>
<br>
<br>
Does anyone know if it is in fact possible to do what I want? If so, can<br>
anyone recommend a good reference or place to start?<br>
<br>
<br>
best regards,<br>
<br>
<br>
Christian<br>
<br>
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