[Paraview] How to display the cellNormals as vectors?

[pieter at redpanda.nl]

Hi Pat, Berk,

Thanks for your replies. Displaying the cellNormals works fine now, but I
still can't select the normals computed in my Python script from the
dropdown menus in the Glyph filter.

I uploaded the relevant .VTU file to my web space, you can find it at
http://redpanda.nl/Out.vtu (look for the data named "Normal", it has X, Y
and Z components).

Could you take a look at it?

Best,
Pieter

> ParaView does a weird thing, in the "Color By" drop down menu, it show an
> array named "cellNormals" but this array doesn't actually exist on the
> data
> object, and it doesn't appear in the information tab.  So, as Berk said,
> you should apply the Generate Surface Normals filter, and make sure you
> check the "Compute Cell Normals" check box.  Then you can use the "Cell
> Centers" to generate point data at the cell centers.  Then you can use the
> Glyph filter to draw the arrows for the cell normals.
>
> Pat
>
>
> On Tue, Apr 16, 2013 at 10:03 AM, Berk Geveci
> <berk.geveci at kitware.com>wrote:
>
>> Does the file actually contain normals? I am guessing not. In that case,
>> do:
>>
>> Extract Surface
>> Generate Surface Normals
>> Glyph
>>
>> If you had a vtp file (polydata) instead of vtu (unstructured grid), you
>> wouldn't need to Extract Surface.
>>
>> -berk
>>
>>
>> On Mon, Apr 15, 2013 at 7:27 PM, Pieter Barendrecht
>> <pieter at redpanda.nl>wrote:
>>
>>> Hi all,
>>>
>>> I have just imported a 3D parametric surface in Paraview (from a .VTU
>>> file generated by a Python script), and I'm wondering how to display
>>> the
>>> cellNormals as actual vectors. Since a cellNormal has an X, Y and Z
>>> component, it should be possible to use these three scalar values to
>>> create
>>> a vector, pointing from the corresponding cell.
>>>
>>> I know I can create a vector field with the Glyph function, but I'm not
>>> sure how to continue from there. I cannot select any Scalars or Vectors
>>> from the two dropdown menus/lists (they are enabled but there is
>>> nothing to
>>> select).
>>>
>>> Any ideas on how to proceed would be very welcome!
>>>
>>> Best,
>>> Pieter
>>>
>>> PS: I'm using Paraview 3.98.1 on a Linux machine.
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>>
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>