[vtkusers] Possibly found a bug in vtkImplicitModeller.cxx

[Bill Lorensen]

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
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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
>
>


-- 
Unpaid intern in BillsBasement at noware dot com
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