I found your answer really interesting, i´ll check the --terrain stuff this week
We´re currently running both Windows XP and Windows Vista
the performance drop is not very huge but it´s there.
We saw this drop while making some stress tests, with 16 islands and 20.000 to
40.000 ive´s each one. The test did not represent any real situation, we just
wanted to see how far we could go and i must admit that OSG did pretty well.
Don´t know what caused the problem, maybe having so many small files makes disk
fragmentation go worse???? having so many opened files causes some kind of
delay??? Maybe the test was a little to extreme??? no idea really, just
guessing.
thanks for answering so fast.
> Date: Wed, 14 May 2008 10:44:55 +0100
> From: [EMAIL PROTECTED]
> To: [email protected]
> Subject: Re: [osg-users] some questions about Virtual Planet Builder
>
> Hi David,
>
> In VPB SVN archive support is temporarily disabled, I do plan to
> re-enable it this month. BTW, what platform are you using? I haven't
> seen a performance delta between archive and non archived forms - I
> work under Linux.
>
> FYI, In OSG-2.4 and VPB SVN there is support for build with --terrain
> in osgdem, that build an osgTerrain::TerrainTile database, these tiles
> are basically regular grids, that osgTerrain can render how it wants.
> There a couple of advantages in using --terrain:
>
> 1) osgdem --terrain databases are much faster to build as no
> simplification is done beyond that introduced by sampling the source
> data, so you'll end up with more triangles, but modern hardware is
> faster so this less of an issue.
>
> 2) osgdem --terrain option also builds more compact databases, which
> will get even more compact once I introduce height field
> compression/decompression into .ive.
>
> 3) Finally if you place an osgTerrain::Terrain object above a paged
> database that contains TerrainTiles you can control the sample
> resolution that the TerrainTechnique that does the rendering of
> TerrainTiles uses when set up its geometry to render.
> This allows you to balance the load for different hardware, so a 8800+
> series could cope with full resolution, and low end
> card you sample to half or quarter the density.
>
> Robert.
>
>
>
> On Wed, May 14, 2008 at 10:29 AM, David _ <[EMAIL PROTECTED]> wrote:
> > Hi
> >
> > we´re using osgdem to generate islands in our project and we´re considering
> > moving to OSG 2.4. We´re currently in 2.2
> >
> > the last osgdem in SVN generates the island meshes with some kind of
> > optimization so the meshes are not so high density but still have high res
> > textures
> >
> > we´re really interested in having high resolution textures with light
> > density meshes so this optimization is really good for us,
> >
> > the problem is that the -a option is currently disabled in the last SVN VPB
> > and we´ve noticed some performance drop in loading time if the ive´s are not
> > all together in one osga file (our islands are more than 1GB each, so this
> > is important)
> >
> > A) which is the last VPB release having this mesh optimization and the -a
> > option?? it must work with OSG 2.4 too
> >
> > B) also, is it possible to tell osgdem to limit the triangle number but not
> > the texture detail???
> >
> > We have a lot of things to do right now, and generating all the islands
> > again is something that can wait at the moment. So if you´re planning to
> > update the VPB any time soon, please tell me and i´ll wait for the -a option
> > to be back again, otherwise, please answer the A) question
> >
> > we´ve got some nice screenshots of the islands rendered by OSG 2.2, i´ll ask
> > my boss this evening if i can make them public, so you all can take a look
> > if you find it interesting
> >
> > cheers
> >
> > sorry for my english
> >
> >
> >
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> >
> >
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