[Paraview] non-symmetric representation of symmetric field

[Mikhail Artemyev]

Dear Magician,

Thank you for the explanation and for the hint!
The only issue is that the last step of your algorithm
   3. apply Resample With Dataset filter,
not always gives the desired result.
I was able to get the same representation like you showed, but
it was an accidental choice of several Resample With Dataset filters,
and I couldn't repeat it again. My impression is that I have to apply
this filter several times to different sources. Am I right?

Thank you.

Best regards,
Mikhail


On 05/17/2014 12:00 AM, Magician wrote:
> Hi Mikhail,
>
>
> Yes, that’s because of the triangulation (or tesselation) of surface 
> representations.
> Most of the 3D programs including ParaView draw objects as groups of 
> triangles.
> That’s depends on today’s 3D rendering pipelines such as OpenGL, 
> DirectX, etc.
> Please googling the keywords: ‘vertex shading’
>
> Even though you read your data as structured grid with point values,
> ParaView should immediately triangulate all of the rectangles, and 
> interpolating
> the values between points of the triangles.
>
> # If you visualize cell values, there are no problem caused by 
> interpolating.
>
> The attached image is one of the solution.
> 1. read your data
> 2. make a ‘fine resolution' Plane source with same size to the 
> original (for example, 200x100 structured grid)
> 3. apply Resample With Dataset filter
> The result looks nearly-symmetric for me.
>
>
> Magician
>
>
> On May 17, 2014, at 10:40, paraview-request at paraview.org 
> <mailto:paraview-request at paraview.org> wrote:
>
>> Date: Fri, 16 May 2014 20:40:18 -0500
>> From: Mikhail Artemyev <artemiev.mikhail at gmail.com 
>> <mailto:artemiev.mikhail at gmail.com>>
>> To: paraview at paraview.org <mailto:paraview at paraview.org>
>> Subject: [Paraview] non-symmetric representation of symmetric field
>> Message-ID: <5376BE02.7050800 at gmail.com 
>> <mailto:5376BE02.7050800 at gmail.com>>
>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"
>>
>> Dear all,
>>
>> Here is a minimal example of values distributed over a mesh:
>>
>> 0------0------0------0------0
>> |        |        |         |        |
>> 0----0.5---0.75---0.5-----0
>> |        |        |         |        |
>> 0------0------1------0------0
>>
>> To visualize this field I wrote a .vts file:
>>
>> <?xml version="1.0"?>
>> <VTKFile type="StructuredGrid" version="0.1" byte_order="LittleEndian">
>>   <StructuredGrid WholeExtent="1 5 1 3 1 1">
>>     <Piece Extent="1 5 1 3 1 1">
>>       <PointData Scalars="scalars">
>>         <DataArray type="Float64" Name="sol_" format="ascii">
>> 0 0 1 0 0 0 0.5 0.75 0.5 0 0 0 0 0 0
>>         </DataArray>
>>       </PointData>
>>       <Points>
>>         <DataArray type="Float64" NumberOfComponents="3" format="ascii">
>> 0 0 0
>> 1 0 0
>> 2 0 0
>> 3 0 0
>> 4 0 0
>> 0 1 0
>> 1 1 0
>> 2 1 0
>> 3 1 0
>> 4 1 0
>> 0 2 0
>> 1 2 0
>> 2 2 0
>> 3 2 0
>> 4 2 0
>>         </DataArray>
>>       </Points>
>>     </Piece>
>>   </StructuredGrid>
>> </VTKFile>
>>
>> The visual representation of this field, however, doesn't look symmetric
>> (a figure is attached),
>> although the values are symmetric with respect to a Y-axis crossing the
>> center of the domain.
>>
>> Could you please shed some light on where I am wrong -
>> in my understanding of visualization technique, or in a way I pass the
>> data to ParaView?
>> I use ParaView 4.1.0 64-bit, Linux.
>>
>> Thank you.
>> Best regards,
>> Mikhail

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