[Paraview] non-symmetric representation of symmetric field

[Magician]

Hi Mikhail,


I need to get more information about your problem.
Can you share your dataset or screenshot?
.pvsm state files are more suitable.


Magician


On May 24, 2014, at 5:33, Mikhail Artemyev <artemiev.mikhail at gmail.com> wrote:

> 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 wrote:
>> 
>>> Date: Fri, 16 May 2014 20:40:18 -0500
>>> From: Mikhail Artemyev <artemiev.mikhail at gmail.com>
>>> To: paraview at paraview.org
>>> Subject: [Paraview] non-symmetric representation of symmetric field
>>> Message-ID: <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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