[osg-users] When optimizing with LOD changes, should I change UV map resolutions?

Rick Pingry rick at fringe-online.com
Thu Jul 10 09:13:39 PDT 2008

Wow, the ability to limit the maximum texture memory sounds like it would
really help.  What/where might I find that environment variable?

-- Rick

On Thu, Jul 10, 2008 at 11:26 AM, Paul Martz <pmartz at skew-matrix.com> wrote:

>  Robert's comment regarding texture atlas usage in low-res LOD children is
> an excellent suggestion.
> Going further, your post begs the question: Do you suspect that texture
> memory usage is the bottleneck to your performance? One way to test this (if
> you haven't already done so) is to set the OSG environment variable to limit
> the maximum texture dimension to something ridiculously small. If your app
> runs faster with this setting, then texture memory usage might be causing
> performance problems, and you might need to address that in some way.
> You should keep in mind that most OpenGL device drivers are smart enough to
> page out large mipmap levels when they are not in use.
> Another thing to keep in mind is that a texture never needs to be larger
> than its max representation on-screen. For example, it's pointless to have a
> 2kx2k texture applied to an object that will never subtend more than 500x500
> pixels.
> Hope that helps.
>    -Paul
>  ------------------------------
> *From:* osg-users-bounces at lists.openscenegraph.org [mailto:
> osg-users-bounces at lists.openscenegraph.org] *On Behalf Of *
> rpingry at gmail.com
> *Sent:* Thursday, July 10, 2008 7:09 AM
> *To:* OpenSceneGraph Users
> *Subject:* [osg-users] When optimizing with LOD changes,should I change UV
> map resolutions?
>   Hello All,
> I have been trying to get my scenes to run faster, balancing my scene
> graphs using LOD.  I use quite a bit of UV mapping in my models, and they
> can be fairly high res because I want them to look good up close.  There are
> usually several instances of the same model in the scene, all pointing to
> the same scene graph.  I was wondering about the best way to create LOD
> changes for them.  I was going to cut out some polygons, but I was also
> thinking of cutting the resolution back on the UV maps.  Is this valuable?
> On first assessment, it seems it would be, but then I realize that it might
> cause MORE of a memory usage, and the graphics card (or OSG) might be doing
> this kind of optimization anyway (dropping image map resolutions based on
> pixel size or whatever).  What are your recommendations?
> -- Thanks for everything
> >> Rick
> Check us out at http://fringe-online.com/
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>> Rick
Check us out at http://fringe-online.com/
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