I'm not familier with the term P1-discontinuous.  Is that the same as not C0 
continuous (or simply not continuous)?

If so, then yes that is a problem.  The VTK data sets do not directly represent 
discontinuous interpolated fields.  The only way to do it is how you describe.  
Replicate the point so that two distinct field values can be placed at the same 
coordinates.  But, as you discovered, this means that the connectivity cannot 
be represented, which can foul up some operations like finding a cell.

I know of no simple away around the problem.  You would need a different cell 
locator that used a different slower but more reliable search.

-Ken

From: Ali Rostai <ali.ros...@gmail.com<mailto:ali.ros...@gmail.com>>
Date: Mon, 17 Oct 2011 09:22:45 -0700
To: Kenneth Moreland <kmo...@sandia.gov<mailto:kmo...@sandia.gov>>
Cc: "paraview@paraview.org<mailto:paraview@paraview.org>" 
<paraview@paraview.org<mailto:paraview@paraview.org>>
Subject: Re: [Paraview] confused with getting nan values in plot over line

Hi and excuse me for late reply,

I tried the "Clean to grid" filter and it seems that problems has been solved. 
But I noticed that
the data was coming from a finite element method using P1-discontinuous 
Triangular elements.
And it looks for me the problem is somehow related to that.

But as a general question Can paraview show P1-discontinuous data? then for 
each node in mesh
we have several values. But I think vtk format accepts only one value for each 
noed.

Regards,
Ali


On Thu, Oct 6, 2011 at 10:34 AM, Moreland, Kenneth 
<kmo...@sandia.gov<mailto:kmo...@sandia.gov>> wrote:
For starters, the going to infinity thing in the plot is weird. There should 
just be gaps in the curve. You may have hit a bug.

As far as why you are getting nans in the first place I'm not sure. I can't 
really tell from your screenshots, but it looks your geometry might be a bunch 
of polygons on a plane. Is that the case? If so, make sure that all z 
coordinates are zero. If all the coordinates in pone dimension are exactly the 
same, then I would expect it to work. Otherwise the line will not be completely 
on it.

If that is not the case, another problem could be with your topology. The find 
cell method could fail if your mesh is not fully connected. For example, if you 
have repeated coincident points, then VTK won't be able to find neighbors and 
trace to a cell. Try running one of the clean filter on the data. I think that 
should fix the problem. I think there are some corner cases where even that 
might not work, but your mesh looks like it has good quality triangles or 
tetrahedra, so that seems unlikely unless you have degenerate cells or gaps I 
cannot see.

-Ken


From: ali rostai [mailto:ali.ros...@gmail.com<mailto:ali.ros...@gmail.com>]
Sent: Thursday, October 06, 2011 08:12 AM
To: Moreland, Kenneth; paraview@paraview.org<mailto:paraview@paraview.org> 
<paraview@paraview.org<mailto:paraview@paraview.org>>
Subject: Re: [Paraview] confused with getting nan values in plot over line

Hi,

I tried and tried to move the start and end of line inside the domain.
Actually I see two lines going to infinity (nan) in xyplot pane now! (screen 
shot attached)

Regards,
Ali

On Thu, Oct 6, 2011 at 5:08 AM, Moreland, Kenneth 
<kmo...@sandia.gov<mailto:kmo...@sandia.gov>> wrote:
Like I said previously, it looks like the line you define is right on the 
boarder of your volume. Try moving the line slightly more inside the volume.

-Ken

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