On Thu, Jan 22, 2009 at 9:38 AM, Jean-Sébastien Guay < jean-sebastien.g...@cm-labs.com> wrote:
> Hi Glenn, > > That's right J-S. osgEarth never actually writes any terrain geometry to >> disk. Rather, it generates terrain tiles at run time as you navigate the >> scene. The only relationship to VPB is that they both use osgTerrain. >> > > OK, that's much clearer. > > Very interesting. If terrain is never written to disk though, won't there > be lots of effort re-done over and over, say in multiple runs of the > software where the user goes over the same areas? You could probably cache > generated terrain to disk since I guess the Earth changes only seldom :-) osgEarth has a configurable caching mechanism that caches source data tiles, so most of the work only happens the first time you encounter a tile. > I guess you generate low LODs first so that the user gets to see something > at least, and then refine as time goes by... What kind of time can you > expect to get good detail, and can you move about freely while the updates > are progressing? Time to bring in new subtiles depends entirely on the data source and its composition. Once the data is cached though, the speed is really not much different than with a VPB database (not that we've actually measured it.) But yes, osgEarth uses the standard PagedLOD, osgTerrain, and ReaderWriter plugin mechanisms, so background paging works just as with a pre-generated terrain. The result is quite similar to what you get with WorldWind, Google Earth, etc. > This sounds a bit like my Masters project, where you could move around a > scene and move/deform objects, and the high-quality lighting would update > progressively without ever stopping interaction. > > Good work, I look forward to trying it out. > > > J-S > -- > ______________________________________________________ > Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com > http://www.cm-labs.com/ > http://whitestar02.webhop.org/ > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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