Hi Shayne, Also, if you're intersecting against a PagedLOD database the highest level of detail of the database is loaded and cached by the DatabaseReadCallback in the osgSim::HeightAboveTerrain class. So if your intersections are grouped spatially together they have a better chance of being able to use what is in the memory cache and don't need to load anything from disk. If you're doing random intersections all over the database then there is a greater chance that it will need to load files from disk and slow things down.
Thanks, Jason On Wed, Jul 28, 2010 at 4:47 AM, Robert Osfield <[email protected]> wrote: > Hi Shyane, > > I've not been at my desk too consistently this last few weeks due to > school holidays, so not able to dig down into all threads. > > A couple of general comments. If intersections are slow then consider > enabling the building KdTree's on your scene graph, this will greatly > improve performance. In osgDB::Options and osgDB::Registry there is a > setBuildKdTreesHint(..) method that you can use. > > Robert. > > On Tue, Jul 27, 2010 at 7:25 PM, Tueller, Shayne R Civ USAF AFMC 519 > SMXS/MXDEC <[email protected]> wrote: >> Since I didn't receive any input or feedback on my previous inquiry, I'm >> assuming no one has used osgSim very much in an extensive setting.?.? >> >> At any rate, I've done some further investigation. It appears that >> performance is very poor when HAT inquiries are randomly called in different >> portions of the code via the >> osgSim::HeightAboveTerrain::computeHeightAboveTerrain(.) method. On the >> other hand, if HAT points via hat.addPoint() are collected up and then >> computed (intersections) in one place, performance improves. I'm assuming >> that this is the correct usage for OSG? If this is true, I must say that >> this is a major problem since HAT inquiries need to be done at different >> times throughout the application due to dependencies on HAT for other >> calculations. >> >> I would like some feedback from someone in the know on osgSim so I know what >> the proper usage is for maximum performance. If it is true that all HAT >> points in OSG need to be consolidated for intersection calculation, then I >> will attempt to refactor the code to support what OSG wants. >> >> Thanks, >> -Shayne >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of >> Tueller,Shayne R Civ USAF AFMC 519 SMXS/MXDEC >> Sent: Friday, July 23, 2010 10:57 AM >> To: OpenSceneGraph Users >> Subject: [osg-users] osgSim HeightAboveTerrain performance... >> >> All, >> >> >> >> I was wanting some feedback for those who have used osgSim in querying VPB >> database info such has HAT, LOS, etc., during runtime. >> >> >> >> I'm seeing some performance issues when using >> osgSim::HeightAboveTerrain::computeHeightAboveTerrain(.) to get the HAT >> value for a particular location in the database. At times, we need multiple >> HAT values per frame which seems to bog the performance down. I would >> surmise that LOS calculations are probably worse since multiple >> intersections are computed. >> >> >> >> My question is, is how efficient is the osgSim HAT function? Is the process >> of retrieving HAT a slow one? If so, is there a way to improve performance >> if one or more HAT requests are issued on a per frame basis? >> >> >> >> Thanks in advance, >> >> -Shayne >> >> >> _______________________________________________ >> osg-users mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >> >> > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
