Certainly if you use OSG as a geometry storage database, then rendering time goes up as complexity goes up.
If you have intimate knowledge of your database, OSG's occluder nodes can be used to cull hidden geometry. osgUtil has a spatial optimizer that can help you take maximum advantage of view and occluder culling. I'm currently working on adding support for OpenGL's hardware-based occlusion query feature, which will add another culling option to the menu. What other kinds of culling are you looking for? Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com 303 859 9466 > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Paul Kahler > Sent: Wednesday, June 27, 2007 7:29 PM > To: [email protected] > Subject: [osg-users] Culling and performance scaling > > I've been poking around on the OSG site and the mailing list > and it's not clear to me how well OSG scales with geometric > complexity (polygon count). I understand view frustum culling > and back-face culling, but it's not clear to me if OSG can do > more than that. For example, if I have an entire town modeled > with terrain, buildings, furniture, under what conditions > will OSG skip drawing a chair inside a room? > > Or more simply, what does OSG do to skip rendering objects > obstructed by other objects? > > Speaking theoretically: back-face culling eliminates about > 1/2 of all polygons. View frustum culling eliminates perhaps > all but 1/4 of polygons in a large city viewed from the > middle of town. From a time complexity standpoint this turns > a O(n) problem where n is the number of polygons, into O(n/8) > which is really just k*O(n) = O(n). A constant improvement > but still linear. Does OSG do better? How? > > I understand that creating impostors and using LOD techniques > can also improve performance, but my question is strictly in > regard to methods that don't simplify geometry (i.e. culling). > > Thanks, > Paul > > > _______________________________________________ > osg-users mailing list > [email protected] > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
