[vtkusers] vtkAppendPolydataFilter vs vtkBooleanOperationPolyDataFilter::Union

[Cory Quammen]

On Thu, Nov 17, 2016 at 11:31 AM, rakesh patil
<prakeshofficial at gmail.com> wrote:
> Hi all,
>
> I am using vtkBooleanOperationPolyDataFilter to perform union of two 3D
> objects. For 3D objects of same height, I find there exists certain cracks
> and holes. So as a workaround I was thinking to use vtkAppendPolyDataFilter.
> So I just wanted to know whether vtkAppendPolyDataFilter is an alternate
> option for union operation performed by vtkBooleanOperationPolyDataFilter.
> The only difference I can see is that the input and output wont be
> triangulated in case of vtkAppendPolyDataFilter.

The result won't be the same if your two objects overlap in space. The
union for overlapping objects should exclude the portions of one input
geometry that are inside the other. vtkAppendPolyDataFilter just globs
everything together.

> Also will there be any improvements done on
> vtkBooleanOperationPolyDataFilter to solve the holes issue in near future?

It's a tough geometric problem. There is a merge request from Adam
Updegrove that improves the operation of the boolean filter [1], but
as I recall another VTK community member had a test cases on which
even it fails.

Best regards,
Cory

[1] https://gitlab.kitware.com/vtk/vtk/merge_requests/1752

> Thanks & Regards
> Rakesh Patil
>
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-- 
Cory Quammen
Staff R&D Engineer
Kitware, Inc.