[vtk-developers] Cell Tree Locator Update

[Andy Bauer]

Hi John,

I'm able to push to gerrit from paraview's vtk.  Do you have the aliases set
up there?  Doing a "git config -l" I get the gerrit-push alias.
Unfortunately, I can't remember exactly how I got that set up.  Maybe trying
"sh Utilities/SetupForDevelopment.sh" from the main VTK directory will do it
though.

Andy

On Fri, Jul 29, 2011 at 8:22 AM, Biddiscombe, John A. <biddisco at cscs.ch>wrote:

> It's very sad that we can't use the "using" syntax thanks to the borland
> and other old compilers, but that's life. (I've patched my version (patch
> attached), but can't push to Gerrit as I'm using the vtk branch from
> paraview, not the vtk one from vtk <sigh>)
>
> The crash is reproducible on my system too. I must confess I didn't try the
> test before as I was more interested in findcell stuff and querying cells
> inside regions etc at the mo.
>
> Stepping through the code I can see that a condition is being missed in the
> split part of the algorithm, but I'm not quite sure yet how to fix it or why
> it is occurring.
>
> It is worth noting that the CellTreeLocator should come with a very large
> health warning : This class will not work on all datasets. It will only work
> when a true disjoint partitioning is available. They don't mention that much
> in the paper (or I didn't pick up on it). One reason for the extra node in
> the ModifiedBSPTree is to handle cells which can't be partitioned into
> either side.
>
> Consider a chess board - imagine 64 quad cells in the dataset. No problem.
> Now add one more cell which is the whole board (ie the hull of the 64 mini
> quads). This will break the CellTreeLocator - cells which overlap other
> cells can't (always) be partitioned nicely. For most datasets this isn't
> going to be a problem as most datasets are well behaved, but when I worked
> on lidar data and triangulating buildings from it many years ago, I often
> found long skinny triangles which could not be binned in either half and the
> extra node solved it nicely.
>
> Anyway, it occurs to me that the test uses 2D polygons (tessellated sphere)
> in 3D space and it may be the bounds check is flawed for this case in the
> split algorithm and needs to be improved. One 2D cell might be axis aligned
> and cause a file somewhere ...
>
> When I get time I'll look into it, but if anyone else fixes it first please
> tell me so that I can not waste any time on it.
>
> JB
>
>
> -----Original Message-----
> From: vtk-developers-bounces at vtk.org [mailto:
> vtk-developers-bounces at vtk.org] On Behalf Of David Gobbi
> Sent: 29 July 2011 02:36
> To: David Doria
> Cc: VTK Developers; Andy Bauer
> Subject: Re: [vtk-developers] Cell Tree Locator Update
>
> On Thu, Jul 28, 2011 at 6:11 PM, David Doria <daviddoria at gmail.com> wrote:
> >
> >> /home/acbauer/CODE/VTK/VTK/Filtering/vtkAbstractCellLocator.h:107:
> warning:
> >> `virtual int vtkAbstractCellLocator::IntersectWithLine(double*, do
> >> uble*, double, double&, double*, double*, int&, vtkIdType&)' was hidden
> >
> > I think these "function was hidden" are fixed by saying "using
> > functionName;" in the subclass, as I've done here:
> >
> http://review.source.kitware.com/#patch,sidebyside,1862,1,Filtering/vtkKdTreePointLocator.h
> >
> > If there is a better way to fix them, I'd like to know about it.
>
> That trick will not work on Visual Studio 7.1, which is still a
> supported compiler for VTK.  It also breaks the wrappers.
>
> If a VTK class overrides one version of IntersectWithLine, then it
> should override all of them.  If need be, you can just define all the
> unneeded ones as inline methods that calls the superclass methods.
>
>  - David
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