Re: [osg-users] Fading LOD transistions
I think it also depends on how you use the LODing. If you do utilise FadeLOD then you can get away with bringing a LOD in later than if you were just relying on the default 'snap' in, as the fade is less likely to catch the eye especially if you are not looking directly at the item in question. The 'snap' will catch the eye therefore you have to have a larger range on the item to help get around catching of the eye. Therefore there is additional loading on the system due to the LOD being in view for longer. Catch 22. John - Original Message - From: "Mike Weiblen" <[EMAIL PROTECTED]> To: "OpenSceneGraph Users" Sent: Saturday, February 16, 2008 9:25 PM Subject: Re: [osg-users] Fading LOD transistions > Thoughts... > > Fade-LOD is an interesting "feature": the concept is to smooth > transitions between LOD switches by rendering two adjacent LODs with > varying transparency to minimize visual popping. However, the whole point > of LOD is to control rendering load, and Fade-LOD *increases* rendering > load (essentially doubling during the fade) at the exact moment you want > it to decrease. > > IMHO, if we're talking about adding a feature, suggest instead Morph-LOD: > interpolating verts from one LOD's geometry to the other's, then adjusting > the actual number of verts after the transition is complete. Of course > that requires more on the database/code side, and for terrain the effect > is more like rolling ocean than ghostly fading. > > My $0.02 on the wonderful continuum of compromises. > cheers > -- mew > > > > On Fri, February 15, 2008 12:38, Judd Tracy wrote: >> Does osg support or has anybody implemented fading between LOD >> transistions? I found an old thread where someone talks about it but no >> word if anything ever happened with it >> http://osgcvs.no-ip.com/osgarchiver/archives/June2003/0162.html >> >> -- >> Judd Tracy >> Institute for Simulation and Training >> University of Central Florida >> 407-882-1405 > > > Mike Weiblen -- Austin Texas USA -- http://mew.cx/ > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Fading LOD transistions
Thoughts... Fade-LOD is an interesting "feature": the concept is to smooth transitions between LOD switches by rendering two adjacent LODs with varying transparency to minimize visual popping. However, the whole point of LOD is to control rendering load, and Fade-LOD *increases* rendering load (essentially doubling during the fade) at the exact moment you want it to decrease. IMHO, if we're talking about adding a feature, suggest instead Morph-LOD: interpolating verts from one LOD's geometry to the other's, then adjusting the actual number of verts after the transition is complete. Of course that requires more on the database/code side, and for terrain the effect is more like rolling ocean than ghostly fading. My $0.02 on the wonderful continuum of compromises. cheers -- mew On Fri, February 15, 2008 12:38, Judd Tracy wrote: > Does osg support or has anybody implemented fading between LOD > transistions? I found an old thread where someone talks about it but no > word if anything ever happened with it > http://osgcvs.no-ip.com/osgarchiver/archives/June2003/0162.html > > -- > Judd Tracy > Institute for Simulation and Training > University of Central Florida > 407-882-1405 Mike Weiblen -- Austin Texas USA -- http://mew.cx/ ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Fading LOD transistions
One approach is to use shaders for fading. Here's a simple example: https://wush.net/websvn/osggis/filedetails.php?repname=osggis&path=%2Ftrunk%2Fsrc%2FosgGIS%2FFadeHelper.cpp Of course you'd need to augment the shaders to support lighting, texturing etc., but you get the idea. -gw On Feb 15, 2008 1:38 PM, Judd Tracy <[EMAIL PROTECTED]> wrote: > Does osg support or has anybody implemented fading between LOD > transistions? I found an old thread where someone talks about it but no > word if anything ever happened with it > http://osgcvs.no-ip.com/osgarchiver/archives/June2003/0162.html > > -- > Judd Tracy > Institute for Simulation and Training > University of Central Florida > 407-882-1405 > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Fading LOD transistions
On Feb 16, 2008 10:54 AM, Robert Osfield <[EMAIL PROTECTED]> wrote: > The core OSG does have a FadeLOD feature. One can implement it a > higher level but its a bit awkward. Type Correction: The core OSG does *not* have a FadeLOD feature. Sorry about the confusion. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] Fading LOD transistions
Hi Judd, The core OSG does have a FadeLOD feature. One can implement it a higher level but its a bit awkward. Robert. On Feb 15, 2008 6:38 PM, Judd Tracy <[EMAIL PROTECTED]> wrote: > Does osg support or has anybody implemented fading between LOD > transistions? I found an old thread where someone talks about it but no > word if anything ever happened with it > http://osgcvs.no-ip.com/osgarchiver/archives/June2003/0162.html > > -- > Judd Tracy > Institute for Simulation and Training > University of Central Florida > 407-882-1405 > > ___ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
