[vtkusers] Point Cloud To Surface

[Biddiscombe, John A.]

Please disregard the stuff I wrote, I forgot this was the vtkusers list and not the paraview list. You can do a similar operation using the vtkGuassiansplatter class which might be more straightforward for your needs. (data->splatter->isosurface)

JB

-----Original Message-----
From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of Biddiscombe, John A.
Sent: 15 May 2013 20:54
To: Kenneth Sloan; vtkusers
Subject: Re: [vtkusers] Point Cloud To Surface

The pv-meshless plugin for paraview has point resampling onto an image/bolume which can then be isosurfaced. You can either use an SPH kernel for the interpolation function or shepard interpolation. Parallel operation is supported and I've used it on point clouds of around a billion particles on 2048 processes. Unfortunately, I don't have time to help if you can't get it working, but some info is on the wiki if you google it.

For serial operation you'd want
Data->vtksphimageresample
for parallel operation you need to use
data->vtkParticlePartitionFilter->vtkSPHImageResample

one day I'll document it fully, but until I get AMR resampling working the code is in a bit of flux. The 'release-3.14' branch should work with paraview 3.14, the 'next' branch used to work with 3.98 but doesn't at the moment as I have broken stuff so I think you'd need paraview 3.14 ...


JB

-----Original Message-----
From: vtkusers-bounces at vtk.org [mailto:vtkusers-bounces at vtk.org] On Behalf Of Kenneth Sloan
Sent: 14 May 2013 23:54
To: vtkusers
Subject: Re: [vtkusers] Point Cloud To Surface

Your basic problem is polynomial explosion of the Delaunay3D computation.

Here's an idea.

a) divide up space into OVERLAPPING chunks.  Each chunk should have a core which belongs ONLY to that chunk, plus a surrounding guard zone which overlaps with adjacent chunks.  

b) solve the iso-surface problem (using Delaunay3D) inside each chunk

c) keep the part of the iso-surface inside the UNshared core of each chunk.

Note that this all depends on your point cloud being somewhat dense and regular.  The idea is that the Delaunay triangulation at the edges of each chunk's core area should match the DTs at adjacent core areas.  To the extent this is NOT true, you will have some stitching artifacts.

There are many details to work out - but these depend on your data.

--
Kenneth Sloan
KennethRSloan at gmail.com


On May 14, 2013, at 06:26 , Simon von Bibra <simfirehawk at gmx.de> wrote:

> Hello Community,
> 
> still no answer to this question. Are there any further ideas?
> 
> Thanks Simon
>> Hello Community,
>> 
>> maybe this question has been asked already, but I could not find a 
>> good answer so far.
>> 
>> I have a cloud of points, where each point has a scalar value. Now I 
>> want to have a iso-surface for a given scalar value.
>> I tried already following approaches:
>> 
>> 1. Create a mesh with Delaunay3D:
>>       Works maybe ok for sizes of up to 10000 points, but for more 
>> points it is unusable 2.  Gaussian Splatter, but here I could not get 
>> it right. In the end I just had some sphere, but no real iso-surface.
>> 
>> I thought, I can maybe regularize the point cloud with something like 
>> marching cubes, but I did not get it to work. Also I will loose 
>> correctness, because of the regular sampling.
>> 
>> Any ideas what will be a good way, to create the correct iso-surface?
>> 
>> Thanks in advance
>> Simon
> 
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