[vtkusers] recommended cell locator for IntersectWithLine tests?

[Dean Inglis]

Hi David,

thanks but the signature I am looking for (I just found out) is only 
implemented in
vtkOBBTree.  I need all the points of intersection along the line.
All the other child classes of vtkAbstractCellLocator just
call the Superclass method in which case it just says:
  vtkErrorMacro(<<"The locator class - " << this->GetClassName()
    << " does not yet support this IntersectWithLine interface");

Dean

>I highly recommend the vtkModifiedBSPTree. It sped up my intersections
>over the OBBTree about 40x. I didn't ever play with those kind of
>settings so I can't recommend any, I just used the defaults and it
>seemed to work fine for my application.


> I am revisiting some old code I wrote to do stereology measurements
> (mean intercept length).  I am rotating a set of evenly spaced parallel
> test lines (in the x-y plane) and during each rotation I need to find all
> the intersection points
> of the lines with a set of perpendicular planes defined by a vtkPolyData
> ( imagine the planes as being the walls of a maze ).  I was using 
> vtkOBBTree
> with the following settings:
>   this->OBBTree->CacheCellBoundsOff();
>   this->OBBTree->AutomaticOff();
>   this->OBBTree->SetMaxLevel( 100 );
>   this->OBBTree->SetNumberOfCellsPerNode( 1 );
>
> but there are some cases wherein not all the interesection points are 
> found.
> The number of "walls" in the "maze" are in the hundreds but less than a
> thousand.
> The walls do not necessarily form closed polygons.  Can anyone recommend
> a more robust locator and if so with some suggested settings?
>