[vtkusers] Possibly found a bug in vtkImplicitModeller.cxx

[Bill Lorensen]

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
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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
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