[vtk-developers] Code review request: biquadratic quadinterpolation

Marcus D. Hanwell marcus.hanwell at kitware.com
Tue Jan 28 10:07:24 EST 2014


Thanks John, I appended a third commit to the topic that makes the two
files consistent. I will see if we can get this merged soon as it
looks correct to me too, and will increase our coverage of some of
this code thanks to the contributed test code.

On Fri, Jan 24, 2014 at 5:17 PM, John Platt <jcplatt at dsl.pipex.com> wrote:
> Hi Marcus,
>
> I looked at vtkQuadraticQuad::EvaluatePosition() (VTK5.10) . This assumes
> the same points for the origins of the linear quads as vtkBiQuadraticQuad...
>
>    subId 0 :  (    0,    0 ) - point 0,  linear quad { 0, 4, 8, 7 }
>             1 :  ( 0.5,    0 )            4,                    { 8, 4, 1, 5
> }  ** inconsistent **
>             2 :  ( 0.5, 0.5 )            8,                    { 8, 5, 2, 6
> }
>             3 :  (    0, 0.5 )            7,                    { 7, 8, 6, 3
> }
>
> It looks like a bug in vtkQuadraticQuad which has been copied into
> vtkBiQuadraticQuad.
>
>
> John.
>
> ----- Original Message ----- From: "Marcus D. Hanwell"
> <marcus.hanwell at kitware.com>
> To: "John Platt" <jcplatt at dsl.pipex.com>
> Cc: "David Thompson" <david.thompson at kitware.com>; "VTK Developers"
> <vtk-developers at vtk.org>
> Sent: Friday, January 24, 2014 6:57 PM
>
> Subject: Re: [vtk-developers] Code review request: biquadratic
> quadinterpolation
>
>
>> Hi John,
>>
>> Thanks for your input - I really appreciate it. I will see if I hear
>> back from the contact David Thompson pointed out, and also try to find
>> some time to look at the vtkQuadraticQuad to ensure they are
>> consistent.
>>
>> Marcus
>>
>> On Thu, Jan 23, 2014 at 6:21 PM, John Platt <jcplatt at dsl.pipex.com> wrote:
>>>
>>> Hi Marcus,
>>>
>>> I tested this change using 5.10 and it did not affect colour mapping,
>>> cutting or clipping. Unfortunately, I don't do any probing so I cannot
>>> check
>>> this.
>>>
>>> There would appear to be a dependency on the starting point for the
>>> linear
>>> quads with the 'adjust parametric coordinates' section in
>>> EvaluatePosition(). Here, the parametric coordinates from the linear quad
>>> are converted to parametric coordinates in the quadratic quad. The
>>> origins
>>> of each linear quad are as follows ...
>>>
>>>  (    0,    0 ) - point 0
>>>  ( 0.5,    0 )            4
>>>  ( 0.5, 0.5 )            8
>>>  (    0, 0.5 )            7
>>>
>>> So I would say that the proposed change is consistent with these origins.
>>>
>>> vtkQuadraticQuad uses the same linear quads as the old vtkBiQuadraticQuad
>>> so
>>> it could be a problem here also.
>>>
>>> HTH
>>>
>>> John.
>>>
>>> ----- Original Message ----- From: "Marcus D. Hanwell"
>>> <marcus.hanwell at kitware.com>
>>> To: "David Thompson" <david.thompson at kitware.com>
>>> Cc: "VTK Developers" <vtk-developers at vtk.org>
>>> Sent: Thursday, January 23, 2014 9:16 PM
>>> Subject: Re: [vtk-developers] Code review request: biquadratic
>>> quadinterpolation
>>>
>>>
>>>> On Thu, Jan 23, 2014 at 3:48 PM, David Thompson
>>>> <david.thompson at kitware.com> wrote:
>>>>>
>>>>>
>>>>> Hi Marcus,
>>>>>
>>>>>> There is a topic on Gerrit I am having trouble finding a reviewer for,
>>>>>> http://review.source.kitware.com/#/t/3848/
>>>>>
>>>>>
>>>>>
>>>>> Soeren Gebbert (soerengebbert at googlemail.com) is the original
>>>>> developer.
>>>>> I'm really swamped right now, but it would be great to verify with
>>>>> Sandia
>>>>> that the change does not mess with the Exodus reader's numbering of
>>>>> nodes
>>>>> within the cell... several changes have done so in the past.
>>>>>
>>>> It would be nice to figure out what the expected behavior is too,
>>>> because this doesn't break any tests I can see. It is a single line
>>>> change, I can email the original developer but don't have much more
>>>> time I can put into this.
>>>>
>>>> Marcus
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>>>
>>>
>>
>
>



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