[vtkusers] Possibly found a bug in vtkImplicitModeller.cxx

Wed Jul 11 10:38:31 EDT 2012

Hello!

It is clamped to be between 0 and 1 but in my tests does not behave as 
being relative. If it were relative, it should surely not be squared. 
Anyway, if You remove the '*' at line 967, the output contains only 
values up to the absolute value specified with SetMaximumDistance.
To my understanding, the value stored in MaximumDistance is used as an 
absolute value in the code and corresponds to the units of the input.
I just tested removing the clamping and allowing any double value yields 
an output reaching up to 10 if SetMaximumDistance(10) is used.
If You agree, I'd therefore suggest not only to remove the '*' but also 
the clamping in the header file.

Thanks for Your comments on this
Roman

On 11.07.2012 14:37, Jothybasu Selvaraj wrote:
> If the bounds are (for simplicity) equal on all side of 5.0, then if I set
> the MaxDistacne to 0.2 ; how it will be aclculated?
>
> Will it be 0.5+ (0.5*0.2)=0.6?
>
> Thanks
>
> Jothy
>
>
>
> On Wed, Jul 11, 2012 at 1:35 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:
>
>> The bounds of the model, either computed or supplied.
>>
>>
>> On Wed, Jul 11, 2012 at 8:24 AM, Jothybasu Selvaraj <jothybasu at gmail.com>wrote:
>>
>>> "MaximumDistance is a percentage"
>>>
>>>
>>> % of what?
>>>
>>> Jothy
>>>
>>>
>>>
>>> On Wed, Jul 11, 2012 at 1:10 PM, Bill Lorensen <bill.lorensen at gmail.com>wrote:
>>>
>>>> MaximumDistance is clamped to be within 0 and 1.
>>>>
>>>> On Wed, Jul 11, 2012 at 8:07 AM, Jothybasu Selvaraj <jothybasu at gmail.com
>>>>> wrote:
>>>>
>>>>> So, for instance what does 10.0 mean?
>>>>>
>>>>> Is it multiplication of the bounds of vtkPolyData?
>>>>>
>>>>> with bounds [-5,5,-5,5,-5,5] the operation will be applied in
>>>>> [-50,50,-50,50,-50,50]
>>>>>
>>>>> Thanks
>>>>>
>>>>> Jothy
>>>>>
>>>>> On Wed, Jul 11, 2012 at 1:03 PM, Bill Lorensen <bill.lorensen at gmail.com
>>>>>> wrote:
>>>>>
>>>>>> MaximumDistance is a percentage, not an absolute distance. The
>>>>>> documentation is not clear about this.
>>>>>>
>>>>>>
>>>>>> On Wed, Jul 11, 2012 at 3:45 AM, Roman Grothausmann <
>>>>>> roman.grothausmann at helmholtz-berlin.de> wrote:
>>>>>>
>>>>>>> Dear mailing list members,
>>>>>>>
>>>>>>>
>>>>>>> Could it be that in vtkImplicitModeller.cxx there is a bug that
>>>>>>> causes the maximum distance (that is calculated and saved in the image) to
>>>>>>> be bigger than specified with SetMaximumDistance()?
>>>>>>>
>>>>>>>  From the description of the filter and its parameters and also from
>>>>>>> the comments in the source I would expect that the output stored in 32-bit
>>>>>>> real does not contain values above SetMaximumDistance() except for the
>>>>>>> "background" value.
>>>>>>>
>>>>>>> Having checked the source it seems to me that the squared distance
>>>>>>> was always very carefully assigned to a variable name ending with 2 (e.g.
>>>>>>> maxDistance2). However at line 967 there is a *= assignment (see patch
>>>>>>> below). Removing the '*', the output image of the filter then fulfils my
>>>>>>> expectations mentioned above.
>>>>>>>
>>>>>>> Could the '*' be a bug?
>>>>>>>
>>>>>>> --- VTK_orig/Hybrid/**vtkImplicitModeller.cxx     2012-05-12
>>>>>>> 13:59:27.000000000 +0200
>>>>>>> +++ VTK/Hybrid/**vtkImplicitModeller.cxx  2012-07-10
>>>>>>> 16:22:21.060066823 +0200
>>>>>>> @@ -967,7 +967,7 @@
>>>>>>>         }
>>>>>>>       }
>>>>>>>
>>>>>>> -  maxDist *= this->MaximumDistance;
>>>>>>> +  maxDist = this->MaximumDistance;
>>>>>>>
>>>>>>>     // Set volume origin and data spacing
>>>>>>>     output->SetOrigin(this->**ModelBounds[0],
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Happy coding
>>>>>>> Roman
>>>>>>>
>>>>>>> --
>>>>>>> Dr. Roman Grothausmann
>>>>>>>
>>>>>>> Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
>>>>>>> Bereich Funktionale Materialien
>>>>>>> Institut für angewandte Materialforschung
>>>>>>> Hahn-Meitner-Platz 1
>>>>>>> D-14109 Berlin
>>>>>>>
>>>>>>> (früher Hahn-Meitner-Institut und BESSY)
>>>>>>>
>>>>>>>
>>>>>>> Tel.: +49-(0)30-8062-42816
>>>>>>> Fax.: +49-(0)30-8062-43059
>>>>>>>
>>>>>>> Vorsitzender des Aufsichtsrats: Prof. Dr. Dr. h.c. mult. Joachim
>>>>>>> Treusch
>>>>>>> Stellvertretende Vorsitzende: Dr. Beatrix Vierkorn-Rudolph
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>>>>>>> Breuer
>>>>>>> Sitz der Gesellschaft: Berlin
>>>>>>> Handelsregister: AG Charlottenburg, 89 HRB 5583
>>>>>>>
>>>>>>>
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>>>>>>
>>>>>>
>>>>>>
>>>>>> --
>>>>>> Unpaid intern in BillsBasement at noware dot com
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> Powered by www.kitware.com
>>>>>>
>>>>>> Visit other Kitware open-source projects at
>>>>>> http://www.kitware.com/opensource/opensource.html
>>>>>>
>>>>>> Please keep messages on-topic and check the VTK FAQ at:
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>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Jothybasu Selvaraj
>>>>> PhD Student
>>>>> University of Liverpool
>>>>> UK
>>>>>
>>>>>
>>>>
>>>>
>>>> --
>>>> Unpaid intern in BillsBasement at noware dot com
>>>>
>>>>
>>>
>>>
>>> --
>>> Jothybasu Selvaraj
>>> PhD Student
>>> University of Liverpool
>>> UK
>>>
>>>
>>
>>
>> --
>> Unpaid intern in BillsBasement at noware dot com
>>
>>
>
>

-- 
Roman Grothausmann

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH
Bereich Funktionale Materialien
Institut für angewandte Materialforschung
Hahn-Meitner-Platz 1
D-14109 Berlin	

(früher Hahn-Meitner-Institut und BESSY)

Tel.: +49-(0)30-8062-42816
Fax.: +49-(0)30-8062-43059

Vorsitzender des Aufsichtsrats: Prof. Dr. Dr. h.c. mult. Joachim Treusch
Stellvertretende Vorsitzende: Dr. Beatrix Vierkorn-Rudolph
Geschäftsführer: Prof. Dr. Anke Rita Kaysser-Pyzalla, Dr. Ulrich Breuer
Sitz der Gesellschaft: Berlin
Handelsregister: AG Charlottenburg, 89 HRB 5583