[osg-users] Need advice for performance tweaks

Tueller, Shayne R Civ USAF AFMC 519 SMXS/MXDEC Shayne.Tueller at HILL.af.mil
Fri Nov 27 11:05:23 PST 2009


Robert,

Thanks for the quick reply. I haven't played with the LOD scale so I'll
explore that. I also like your suggestion of some sort of adaptive setting. 

Is there a way to query the frame time of the previous frame?

Thanks,
-Shayne

-----Original Message-----
From: osg-users-bounces at lists.openscenegraph.org
[mailto:osg-users-bounces at lists.openscenegraph.org] On Behalf Of Robert
Osfield
Sent: Friday, November 27, 2009 11:08 AM
To: OpenSceneGraph Users
Subject: Re: [osg-users] Need advice for performance tweaks

Hi Shayne,

You can use the osgTerrain::Terrain::setSampleRatio(float) to cut down
geometry complexity alone, and use osg::Camera::setLODScale(float) to
make the selection of LOD's more aggressive.

One thing you could do is implement an adaptive setting of
LODScale/SampleRatio by looking at the frame time of the previous
frame and it is looks close to breaking frame change the ratio's to
reduce the overhead, this way you might be able to get away with
better visuals when the hardware can cope such as looking downwards,
and only go for low high res visuals when you are looking at a shallow
angle to the horizontal when lots of tiles will be in view.

Robert.

On Fri, Nov 27, 2009 at 6:00 PM, Tueller, Shayne R Civ USAF AFMC 519
SMXS/MXDEC <Shayne.Tueller at hill.af.mil> wrote:
> All,
>
>
>
> I have a need to run my OSG app on some "marginal" hardware (single CPU
with
>
> a GeForce 4800 for example) while still maintaining some decent frame
rates
>
> (around 30fps). I want to use the same terrain database (built with VPB
with
> the
>
> -terrain option) if possible.
>
> I've used the setSampleRatio() method in the osgTerrain class and culling
>
> backfaces to thin out the geometry with some success but I'm still not
where
>
> I need to be. As a result, I'm wanting to optimize a bit more if possible.
>
> Does anyone have any suggestions for particular settings in the
>
> databasepager or pagedLOD that I could try to achieve better performance?
>
> I'm willing to sacrifice database fidelity to maintain decent frame rates
if
>
> I must.
>
>
>
> Thanks for any suggestions in advance.
>
> Shayne
>
>
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>
_______________________________________________
osg-users mailing list
osg-users at lists.openscenegraph.org
http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/x-pkcs7-signature
Size: 6028 bytes
Desc: not available
URL: <http://lists.openscenegraph.org/pipermail/osg-users-openscenegraph.org/attachments/20091127/0372d77e/attachment.bin>


More information about the osg-users mailing list