[MOAB-dev] Bug in kdtree?

[Andrew Davis]

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 smartphoneIulian 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 second run, 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




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