[vtk-developers] vtkCutter modification to use vtkCellLocator

[Rostislav Khlebnikov]

Hi,

well, basically, I feel that it is necessary to create a proper change 
to use Gerrit workflow successfully. Unfortunately, I don't quite have 
the time to do this properly for several reasons. One of them is that I 
actually don't need this change - for my project I integrated the 
CGAL-based cutting approach with AABB_tree which outperforms my VTK test 
- for example for the same test with 500k triangles CGAL-based cutting 
takes only 2ms. This will soon be integrated to MITK (in case anyone is 
interested, the pull request can be found here: 
https://github.com/MITK/MITK/pull/73). Making a proper VTK change would 
involve quite a lot of effort. Given that vtkCutter is very general and 
rejecting the octree nodes might be complex for arbitrary implicit 
functions, it seems to require quite a lot of work to avoid incorrect usage.

I can clean up the code a bit and post it to the mailing list if you are 
interested.

All best,
    Rostislav.


On 15/09/2014 15:02, Gerrick Bivins wrote:
>
> Hi Rostislav,
>
> Did anything happen with this?
>
> I would definitely be interested in this capability/feature/improvement.
>
> Gerrick
>
> *From:*vtk-developers [mailto:vtk-developers-bounces at vtk.org] *On 
> Behalf Of *Berk Geveci
> *Sent:* Tuesday, August 12, 2014 11:44 AM
> *To:* Rostislav Khlebnikov
> *Cc:* VTK Developers
> *Subject:* Re: [vtk-developers] vtkCutter modification to use 
> vtkCellLocator
>
> Hi Rostislav,
>
> This is great. Can you push the code to Gerrit 
> (http://review.source.kitware.com/)?
>
> Best,
>
> -berk
>
> On Sat, Aug 9, 2014 at 2:52 PM, Rostislav Khlebnikov 
> <rostislav.khlebnikov at kcl.ac.uk 
> <mailto:rostislav.khlebnikov at kcl.ac.uk>> wrote:
>
> Hi guys,
>
> just thought that the VTK developers might be interested in the test I 
> made recently.
>
> Bascially what I did is subclass the vtkCellLocator to implement the 
> visitor pattern. It allows to filter the octree nodes (e.g. reject the 
> octree nodes that are of no interest early) and for leafs, to visit 
> the cells of the polydata.
> Then, I subclassed the vtkCutter to use this cell locator instead of 
> straight iteration over cells. Likely for very complex implicit 
> cutting functions this wouldnt be of any benefit. However, for those 
> which can test bboxes as being of interest or not, rejecting whole 
> subtrees, such as vtkPlane, it is very useful. I tested it on a 
> surface with 500k triangles and the cutter performance went from 88ms 
> per cut to 14ms.
>
> The code I made is quite ugly due to limited extensibility of 
> vtkCutter, so I had to copy-paste the RequestData method and make my 
> changes instead of, say, overriding IterateCells method which would 
> just provide the cells to cut through.
>
> But anyway, I was wondering if you guys are intersted in this kind of 
> functionality? Would you like me to send you the code?
>
> All best,
>    Rostislav.
>
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