[vtk-developers] Best fit plane function location

[Karthik Krishnan]

David was trying to consolidate the existing vtkTextureMapToPlane and
delaunay use cases. the former does use vtkDataSet::GetPoint since the
class derives from vtkDataSetAlgorithm and any change to disallow a
generic vtkDataSet would break BCP.

thanks

On Mon, Jan 25, 2010 at 8:01 AM, Will Schroeder
<will.schroeder at kitware.com> wrote:
> David-
>
> I really do not want to start collecting geometric operations in a new
> geometric utilities class. Currently (for better or for worse) the VTK
> geometric operations are associated with the various cells with which they
> are consistent. This utility would be yet another place to look for stuff
> and is not consistent with what's in VTK now.
>
> The vtkPlane problem was that one of the best fit plane arguments was a
> vtkDataSet* which resulted in linkage problems. Another way to accomplish
> something similar is to not use vtkDataSet*, instead use vtkPoints*; note
> that vtkPlane is already in VTK/Common. More often than not you are going to
> fit a plane to a set of points explicitly represented by vtkPoints
> (subclasses of vtkPointSet). I'd expect only in rare circumstances are you
> going to traverse points using vtkDataSet::GetPoint(ptId) since this would
> correspond to implicit datasets such as images. If necessary you could
> always populate a vtkPoints from an implicit dataset (use random sampling or
> even the whole population, better yet I would argue that implicit datasets
> typically have closed-form solutions to the best fit plane).
>
> Will
>
> On Sat, Jan 23, 2010 at 9:30 PM, David Doria <daviddoria+vtk at gmail.com>
> wrote:
>>
>> On Fri, Jan 22, 2010 at 4:05 PM, Dean Inglis <dean.inglis at camris.ca>
>> wrote:
>>>
>>> Hi David,
>>>
>>> could this be added to vtkMath?  Or what about starting
>>> a vtkGeometryUtilities or vtkGraphicsUtilities to hold static
>>> methods that are not really worthy of creating a filter class around?
>>>
>>> Dean
>>>
>>> Subject: [vtk-developers] Best fit plane function location
>>>
>>>
>>>> If you'll recall, a while back we tried to add a BestFitFroMPoints
>>>> function
>>>> to vtkPlane. This caused some issues with cross-library linkage. Is this
>>>> big
>>>> enough to make a separate class: vtkBestFitPlane (or maybe
>>>> vtkLeastSquaresPlane)?
>>>>
>>>> I noticed that there is no vtkImplicitFunctionAlgorithm, so is this
>>>> usually
>>>> not done?
>>>>
>>>> I'm thinking something like:
>>>> vtkPoints* points = vtkPoints::New();
>>>> // ... fill points....
>>>> vtkBestFitPlane bestFitFilter = vtkBestFitPlane::New();
>>>> bestFitFilter->SetInput(points);
>>>> bestFitFilter->Update();
>>>>
>>>> vtkPlane* bestPlane = bestFitFilter->GetOutput();
>>>>
>>>> Thoughts?
>>>>
>>>> Thanks,
>>>>
>>>> David
>>>>
>>>>
>>
>> For now I could add it to vtkMath, but as you suggest, we wouldn't want to
>> clutter vtkMath. I like the idea of a vtkGeometricUtilities class for things
>> like this.
>> Any other thoughts? Anyone agree/disagree?
>> Thanks,
>>
>> David
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>
>
>
> --
> William J. Schroeder, PhD
> Kitware, Inc.
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