[osg-users] Improving performances

[Julien Valentin]

Hi Ale
If I read you correctly,you're said to be gpu bound because of the huge amount of vertices to process.
You're also saying you're working with CAD representation (which  AFAIK have parametric representation(shape) )
I think the good approach is to keep your geometry parametric (shape) and update geometry parameter (and so on explicit geometry) based on viewer distance...

Hope it helps in some way:/
Cheers



Ale wrote:
> Hi,
> 
> I posted some question about OSG performance in the past and now I would like to definitively improve visualization performance of my application.
> I want to say that now I already have very good performances with OSG but now I need to start thinking how to manage also some "extreme" scenes.
> 
> It is a CAD-like application and a possible scene is composed by some objects (let's say from 1 to some hundreds) each one with 100K to some millions of triangles. 
> Each of these objects can have up to some thousands of children each one with around 100 triangles.
> For all objects I use vertexbuffer instead of display lists to reduce waiting time at first draw (due to display list compilation).
> I use a matrixtransform for each object and few groups for all the scene.
> Normally objects are not modified but sometimes they can be modified on the fly by user. So I did not set DataVariance (I supposed it is set automatically to STATIC if I did not modify an object).
> The application is GPU bounded as I can see from on-screen stats.
> 
> I cannot merge objects or groups into one becouse I need to do some operations on them so I need to keep them separated.
> I am using KdTrees to improve object picking, it now works well but the interaction is still not smooth becouse of the slow frame rate.
> I think I cannot use LODs becouse triangle reduction on-the-fly can take very long time on this type of scenes.
> I tried with osgViewer and more or less it have the same performance of my application.
> At the moment I can just show bounding boxes for raw scene manipulation but often I need to show object details.
> 
> Could you give me some hint to improve performances? I hope information I give you are enough to do a first analysis.
> At the moment I am not able to setup such a scene to send you screenshots of the stats but I can do it in next days if needed.
> 
> Thank you in advance.
> 
> Best regards,
> Ale


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