Hi Gordon,
we had similar problem here. We were standing exactly at the edge of 2
adjacent triangles in large terrain database and
osgUtil::LineSegmentIntersector failed because of internal floating
precision. Using doubles instead of floats inside
osgUtil::LineSegmentIntersector solved our problems.
I've made submission on 18.02.2009 with modified LineSegmentIntersector
using cmake flag to set float or double precision internally but it
never got into the trunk. You can look at it and create your own
LineSegmentIntersectorDbl : public LineSegmentIntersector with double
maths inside. Perhaps this will help - it did in our case
Best,
Marcin Prus
Tomlinson, Gordon pisze:
HI All
I posting this for one of my folks who's is having some erratic
results when using a long vertical line segment and the standard
osgUtil::LineSegmentIntersector
Basically when he sets a line segment up with end X,Y, 1000000 and
start X,Y, -1000000 , occasionally we fail to get a hit even though we
are in the middle of the terrain skin, although moving the X,Y several
meters in any direction and we get a hit.
If we reduce the Z of the line segment to 500k and -500k this happens
less errant fails,
if we reduce the Z's to 1k, -1k then we never get a fail,
further when we are failing with the intersections if the camera is
further away from the intersection the less fails we get, the more we
move closer to the intersection point the more fails we get.
Our Near and Far clip are fixed, 1 to 10-20k , the terrain skin is
stanard OSG geometry, nothing fancy, some lods, but the level and
which lod is showing does not seem to be the issue
I'm at at a loss to why this may be happening, we are not doing
anything out the oridnary in this case that I can think that would
cause this erratic behaviour ,
any one seen anything like this before ?
thanks
/Gordon
Product Manager 3d
/__________________________________________________________
/Gordon Tomlinson
//Email / : gtomlinson @ overwatch.textron.com
__________________________________________________________
//(C)//:/ (+1) 571-265-2612*
*(W)//:/ //(+1) 703-437-7651//
"Self defence is not a function of learning tricks
but is a function of how quickly and intensely one
can arouse one's instinct for survival"
- */Master Tambo Tetsura/*
------------------------------------------------------------------------
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
--
Marcin Prus
Kierownik Projektu
------------------------------------------------------------------------
ETC-PZL Aerospace Industries Sp. z o.o.
Al. Krakowska 110/114, P.O. Box 22
02-256 Warszawa
http://www.ai.com.pl
tel: (48-22) 846-54-17 wew. 135
fax (48-22) 846-54-18
e-mail: [email protected]
NIP 522-01-01-817 KRS 0000010025
Sa;d Rejonowy dla m. st. Warszawy w Warszawie
XIII Wydzia? Gospodarczy Krajowego Rejestru Sa;dowego.
Wniesiony kapita? zak?adowy Spó?ki wynosi 1 000 000 z?otych.
_______________________________________________
osg-users mailing list
[email protected]
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
