[Paraview] generic NetCDFreader support for CellData

[Cory Quammen]

Joeri,

You can try the "Point Data to Cell Data" filter, but that averages the
point data and places the results in the cell data. You may wind up with
some incorrect values using that approach.

Better would be to use a "Progammable Filter" to resize the cartesian grid
read by the NetCDF reader and treat the point data as cell data. That is a
bit involved, but not terrible. Set the Script to

dims = inputs[0].GetDimensions()

ext = inputs[0].GetExtent()

output.SetDimensions(dims[0]+1, dims[1]+1, dims[2]+1)

output.SetExtent(ext[0], ext[1]+1, ext[2], ext[3]+1, ext[4], ext[5]+1)

inputPd = inputs[0].GetPointData()

outputCd = output.GetCellData()

outputCd.SetScalars(inputPd.GetScalars())


This assumes that the NetCDF reader is producing a vtkImageData (you can
check under the Information panel) which would report the Type: of the data
set as "Image (Uniform Rectilinear Grid).

HTH,
Cory

On Wed, May 2, 2018 at 10:17 AM Engelen, J. van (Joeri) <j.vanengelen1 at uu.nl>
wrote:

> Hi,
>
>
>
> I was wondering whether it is possible to read NetCDF files as CellData.
>
>
>
> I have categorial data on Cartesian coordinates that I want to visualize.
> To be more specific, the data represents lithologies of the subsurface. So
> 1 = sand, 3 = clay, 5 = rock.
>
> The problem is that my file is automatically interpreted as PointData. To
> render this PointData, Paraview than consequently interpolates to achieve
> cell values.
>
> With most variables that is not such a problem, but here it is. If I have
> sand (1) overlying rock (5), Paraview shows me clay (3).
>
>
>
> Also, the information available to me was ambiguous,
>
> -this source says it is probably not possible:
>
> https://public.kitware.com/pipermail/paraview/2017-September/040984.html
>
> -this states it is possible return Cell Data information:
>
>
> https://www.paraview.org/ParaView/Doc/Nightly/www/py-doc/paraview.simple.NetCDFReader.html
>
>
>
> I tried converting my data from NetCDF to a .vtr file in Python, but this
> resulted in more problems than solutions. (Just gave me very glitched
> rendering).
>
>
>
> So I have two questions:
>
> -Is this possible?
>
> -Are there any workarounds you can think of to get my data as CellData in
> Paraview?
>
>
>
> I’m using Paraview v5.4.1 on Windows 7.
>
>
>
> Kind regards,
> Joeri
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-- 
Cory Quammen
Staff R&D Engineer
Kitware, Inc.
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