[MOAB-dev] Bug in kdtree?
Tim Tautges
tautges at mcs.anl.gov
Fri Jul 26 07:52:52 CDT 2013
On 07/25/2013 05:14 PM, Iulian Grindeanu wrote:
>
>
> ------------------------------------------------------------------------------------------------------------------------
>
> so the entities come out ordered according to the distance only if the max_ints is set.
> (only the first max_ints are returned, with the closest distance from the source of the ray)
> The bug is fixed now.
>
> So do you think that we should order them in all cases, for consistency?
>
Yes.
> then we should order them also for OBB tree. Do we have other trees with ray intersecting capability?
>
Yes. But, let's wait until I push all the changes on tree redesign before doing that.
- tim
> That makes sense.
>
> Iulian
>
> ------------------------------------------------------------------------------------------------------------------------
>
> I do think the entries should be ordered at the end of the call, after tree traversal is done, though.
>
> - tim
>
> On 07/24/2013 04:35 PM, Iulian Grindeanu wrote:
> > the bug is around that logic, that I try to understand.
> > It seems that the "ray_end" is reset, which is why some points are missed.
> >
> > I didn't write that logic, maybe Tim or Paul know who did.
> >
> > I don't think we should guarantee the order;
> > The user should order it if needed;
> >
> > The "leafs" of the tree can come in any order, and we should not try to order it there.
> >
> > Iulian
> >
> >
> ------------------------------------------------------------------------------------------------------------------------
> >
> >
> > Hi iulian
> >
> > Thanks for that, additional side question. When you specify the maximum number of intersection to return,
> the list
> > is ordered in distance from the start point, when you specify 0, the list is unordered. Should we not expect
> > consistent behavior in both cases?
> >
> > Thanks
> >
> > Andy
> >
> >
> >
> > Sent from my Samsung Galaxy Note™, an AT&T LTE smartphone
> >
> > Iulian Grindeanu <iulian at mcs.anl.gov> wrote:
> > it works fine if you do not specify the limit 100 for number of intersections.
> > If you leave it 0, it is fine;
> > (so call with kdtree->ray_intersect_triangles( kdtree_root, 1.0e-6,
> > dir, box_center,
> > intersection_facets
> > , intersections);
> >
> > I am still looking, but I think I am close :)
> >
> >
> ------------------------------------------------------------------------------------------------------------------------
> >
> > OK, obb tree works fine with the same model, default setting for everything
> > (you do no have to put tetras in the build, only the faces)
> >
> > So there might be an issue with the kdtree.
> > I will look at it.
> >
> > Iulian
> >
> ------------------------------------------------------------------------------------------------------------------------
> >
> > The problem is on the secondrun, moving the starting point in the to y=4, then we get no
> intersections
> > beyond 48.5.
> > On 07/24/2013 10:50 AM, Iulian Grindeanu wrote:
> >
> > I see no error
> > Your fifth slab is at about 49.5;
> > (first at 9.5, ..., fifth at 49.5)
> >
> > Iulian
> >
> >
> ------------------------------------------------------------------------------------------------------------------------
> >
> > I think I may have found a bug in kdtree.
> >
> > My test problem consists of a tet mesh that is composed of some 4000
> > tets. The mesh looks like that in mesh.png, a ray starts at position
> > (1,0,0) and fires along (1,0,0) and we get the following results back
> > from my test program swp.cpp
> >
> > Compile the minimum working example as
> >
> > g++ swp.cpp -I/<moab include dir> -L<moab lib dir> -lMOAB
> >
> >
> > This is as expected,
> >
> > # of intersections : 20
> > intersection distances are on 8.5 8.74072 9.25928 9.5 18.5 18.7407
> > 19.2593 19.5 28.5 28.7407 29.2593 29.5 38.5 38.7407 39.2593 39.5 48.5
> > 48.7407 49.2593 49.5 of ray length 900
> >
> > 8.5 9.5 18.5 19.5 etc are the boundaries of the faces of the mesh.
> >
> > However, if we recompile and change the starting position to (1,4,0) we get
> >
> > # of intersections : 17
> > intersection distances are on 8.5 8.63513 9.06064 9.5 18.5 18.6351
> > 19.0606 19.5 28.5 28.6351 29.0606 29.5 38.5 38.6351 39.0606 39.5 48.5 of
> > ray length 900
> >
> > As far this ray is concerned there is no mesh in the 5th slab.
> >
> > What have I done wrong?
> >
> > Thanks
> >
> > Andy
> >
> >
> >
> >
> >
> >
>
> --
> ================================================================
> "You will keep in perfect peace him whose mind is
> steadfast, because he trusts in you." Isaiah 26:3
>
> Tim Tautges Argonne National Laboratory
> (tautges at mcs.anl.gov) (telecommuting from UW-Madison)
> phone (gvoice): (608) 354-1459 1500 Engineering Dr.
> fax: (608) 263-4499 Madison, WI 53706
>
>
>
--
================================================================
"You will keep in perfect peace him whose mind is
steadfast, because he trusts in you." Isaiah 26:3
Tim Tautges Argonne National Laboratory
(tautges at mcs.anl.gov) (telecommuting from UW-Madison)
phone (gvoice): (608) 354-1459 1500 Engineering Dr.
fax: (608) 263-4499 Madison, WI 53706
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