[vtkusers] Possibly found a bug in vtkImplicitModeller.cxx

[Jothybasu Selvaraj]

"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
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>>>
>>>
>>>
>>> --
>>> Unpaid intern in BillsBasement at noware dot 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
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