[vtkusers] Possibly found a bug in vtkImplicitModeller.cxx

[Jothybasu Selvaraj]

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)
>>>>>>
>>>>>>
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>>>>>>
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>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Unpaid intern in BillsBasement at noware dot com
>>>>>
>>>>>
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>>>>> Powered by www.kitware.com
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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
>
>


-- 
Jothybasu Selvaraj
PhD Student
University of Liverpool
UK
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