[Paraview] Delaunay3D

[Weiguang Guan]

Hi Kenneth,

Sorry for my unclear description of the problem in previous emails. You 
actually explained what happened in the second paragraph of your email. 
Now I do "Extract Edges" and see all the edges. But yesterday I saw some 
internal points have no edges connecting to them (I referred them as 
dangling points) when displaying the Delaunay triangulation grid in 
wireframe, and didn't realize it shows only the wireframe of the 
surface. Thank you for pointing this out. It all makes sense now.

Best,
Weiguang


On 5/22/2018 4:15 PM, Moreland, Kenneth wrote:
>
> Weiguang,
>
> I just want to clarify something quickly with your question. When you 
> say “some of the points are ignored in the process of Delauney 
> triangulation” and “dangling points,” do you mean that you can see 
> some spheres that are inside the rest of the spheres?
>
> I note in your description that you said you are looking at the 
> wireframe of the Delaunay triangulation. The wireframe representation 
> actually only shows the wireframe of the /surface/. You will not see 
> the edges on the interior of the mesh, so any points that are on the 
> interior will not look connected even if they are.
>
> Instead of showing the wireframe, run the Extract Edges filter (which 
> will show a wireframe of /all/ edges). Does that connect the points 
> like you expect?
>
> -Ken
>
> *From:*ParaView [mailto:paraview-bounces at public.kitware.com] *On 
> Behalf Of *Weiguang Guan
> *Sent:* Tuesday, May 22, 2018 1:58 PM
> *To:* Will Schroeder <will.schroeder at kitware.com>
> *Cc:* paraview at public.kitware.com
> *Subject:* [EXTERNAL] Re: [Paraview] Delaunay3D
>
> Hi Will,
>
> Thank you very much for your time. I've tried v5.5 and v5.2. This 
> "issue" doesn't seem to have anything to do with the versions.
>
> First of all, I would like to change my words for the N=5 case, where 
> there might be 2, 3, or even 4 terahedra depending on the relative 
> locations of the 5 points.
>
> However, the question for the N=20 case is still pending one. You can 
> see the dangling points if you change the representation from 
> "surface" to "wireframe". I basically have similar result as yours. 
> Because the point source generates point cloud with random positions 
> of points, you will see different results each time you change the 
> parameters of Point Source (either number of point or the radius).
>
> Another question: is there another filter that constructs a grid from 
> a set of points?
>
> Weiguang
>
>
> On 5/22/2018 3:42 PM, Will Schroeder wrote:
>
>     What version of ParaView? Mine works just
>     fine..... 5.5.0-323-g37ce137a21 64-bit
>
>     image.pngimage.png
>
>     On Tue, May 22, 2018 at 3:05 PM Weiguang Guan
>     <guanw at rhpcs.mcmaster.ca <mailto:guanw at rhpcs.mcmaster.ca>> wrote:
>
>         Dear Paraview users,
>
>         Based on the documentation, Delaunay3D will construct a 3D
>         Delaunay triangulation from a list of input points if alpha=0.
>         But I did an experiment that gave a different result. Here are
>         the steps:
>         (1) Sources->Point source, and set Number of points to N (I
>         experiment with different N=5 and N=20)
>         (2) Using sphere glyph to display these points
>         (3) Apply filter "Delaunay 3D" to the points with alpha=0 and
>         display the resultant unstructured grid as wireframe.
>
>         When N=20, I can see some of the points are ignored in the
>         process of Delauney triangulation.
>         When N=5, The resultant unstructured grid has 3 cells while I
>         think it should have only 2 tetrahedra.
>
>         Can someone explain it? Thanks a lot.
>
>         Weiguang
>
>         _______________________________________________
>         Powered by www.kitware.com <http://www.kitware.com>
>
>         Visit other Kitware open-source projects at
>         http://www.kitware.com/opensource/opensource.html
>         <http://www.kitware.com/opensource/opensource.html>
>
>         Please keep messages on-topic and check the ParaView Wiki at:
>         http://paraview.org/Wiki/ParaView
>         <http://paraview.org/Wiki/ParaView>
>
>         Search the list archives at:
>         http://markmail.org/search/?q=ParaView
>         <http://markmail.org/search/?q=ParaView>
>
>         Follow this link to subscribe/unsubscribe:
>         https://public.kitware.com/mailman/listinfo/paraview
>
>
>     -- 
>
>     William J. Schroeder, PhD
>     Kitware, Inc. - Building the World's Technical Computing Software
>     28 Corporate Drive
>     Clifton Park, NY 12065
>     will.schroeder at kitware.com <mailto:will.schroeder at kitware.com>
>     http://www.kitware.com
>     (518) 881-4902
>
>
>
>
> -- 
> --
> Weiguang Guan
> Research Scientist
> RHPCS, McMaster University
> Phone: 905-525-9140 x22540


-- 
--
Weiguang Guan
Research Scientist
RHPCS, McMaster University
Phone: 905-525-9140 x22540

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://public.kitware.com/pipermail/paraview/attachments/20180523/6631a31d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/png
Size: 56044 bytes
Desc: not available
URL: <https://public.kitware.com/pipermail/paraview/attachments/20180523/6631a31d/attachment.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: image/png
Size: 75217 bytes
Desc: not available
URL: <https://public.kitware.com/pipermail/paraview/attachments/20180523/6631a31d/attachment-0001.png>