[Paraview] Extract Point Data | Nearest Neighbor Location

[Fastl, Thomas]

Hey Sebastien,

That's correct, the 'Extract Surface' filter applied to the UNSTRUCTURED_GRID (vtk file 1) results in more POINTS compared to the POINTS in the POLYDATA (vtk file 2). In addition, the POINTS in POLYDATA (vtk file 2) have some rounding error so that the location of 'corresponding points' doesn't match exactly.

Maybe you've already suggested the right approach: Is there a way in ParaView to extract the nearest neighbor of all the POINTS in POLYDATA (vtk file 2) from the UNSTRUCTURED_GRID (vtk file 1)? I could just write a csv file of the POINTS in the POLYDATA (vtk file 2) if that'd makes the nearest neighbor approach in ParaView more simple? Thanks.

Best, Thomas

________________________________
From: Sebastien Jourdain <sebastien.jourdain at kitware.com>
Sent: Friday, August 3, 2018 9:11:54 PM
To: Fastl, Thomas
Cc: paraview
Subject: Re: [Paraview] Extract Point Data | Nearest Neighbor Location

So you are saying that the ExtractSurface on the Unstructured grid won't produce the same polydata since it will be more refined than your file2? If that's the case, then maybe just looking for point closer could be the solution.

On Fri, Aug 3, 2018 at 10:56 AM Fastl, Thomas <thomas.fastl at kcl.ac.uk<mailto:thomas.fastl at kcl.ac.uk>> wrote:

Hey Sebastien,


the UNSTRUCTURED_GRID (vtk-file 1) has around 10^8 POINTS, while the POYDATA (vtk-file 2) has around 10^6 POINTS, i.e., the POINTS in vtk-file 2 are a subset of the POINTS in vtk-file 1. Additionally, the POINTS in vtk-file 2 have some rounding error so that the location of "corresponding points" doesn't matches exactly and a nearest neighbor seems necessary.


Best, Thomas

________________________________
From: Sebastien Jourdain <sebastien.jourdain at kitware.com<mailto:sebastien.jourdain at kitware.com>>
Sent: Friday, August 3, 2018 17:20
To: Fastl, Thomas
Cc: paraview
Subject: Re: [Paraview] Extract Point Data | Nearest Neighbor Location

If they are truly the "same" why don't you forget your file2 and generate a polydata from the file1 as a file3?

On Fri, Aug 3, 2018 at 9:41 AM Fastl, Thomas <thomas.fastl at kcl.ac.uk<mailto:thomas.fastl at kcl.ac.uk>> wrote:

Dear Community,


I've got an UNSTRUCTURED_GRID (vtk-file 1) with POINT_DATA and want to extract the POINT_DATA at specific POINTS. However, the POINTS are defined in POLYDATA (vtk-file 2) and are slightly off by some rounding error. Thus, I presume the process should look similar to:


1) Find the nearest neighbors of all POINTS defined in vtk-file 2 in vtk-file 1

2) Transfer/Store the POINT_DATA of the nearest neighbors in vtk-file 1


I've been searching the forum for hours, however, couldn't find a solution to that problem. I was wondering if there's a simple solution of doing this in Paraview? I'd really appreciate your help on this issue, thank you!


Best, Thomas

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