[vtkusers] How to visualize thousands of actors with good performance

[Affolter Martin]

Karthik

I have built vtk 5.0.4 in release with debuginfo and compared the performance while rotating in two instances of our application. I don't have any measuring results but here is what we noticed:

- The performance is better than with 5.6, but not as good as with 4.4 (It seems to be somewhere between 4.4 and 5.6).
- With 24'000 actors in 4.4 I observe about the same performance as with 8'000 actors in 5.0.4

If you know an easy way to show the fps of the renderwindow on screen, please let me know.

Martin 

http://institute.ntb.ch/inf.html 

Von: Karthik Krishnan [mailto:karthik.krishnan at kitware.com] 
Gesendet: Mittwoch, 29. September 2010 15:11
An: Affolter Martin
Cc: "Björn Zehner"; vtkusers at vtk.org
Betreff: Re: [vtkusers] How to visualize thousands of actors with good performance

2010/9/29 Affolter Martin <martin.affolter at ntb.ch>
 The example I used for comparison has about 8000 actors, but we also have bigger models with several 10'000 actors. I honestly doubt, that our problem is OpenGL related. We've been using VTK 4.2 and VTK 4.4 for some years now and have never had performance issues so far. Those only emerged after we moved to VTK 5.6.

Interesting. 

There are two *major* changes between VTK4.4 and now. 
- The painter infrastructure. (introduced in VTK-5-2)
- New pipeline. (Introduced in VTK-5-0)

An interesting exercise would be to update to VTK-5-0 (before the painters but after the new pipeline) and check the performance.

--
karthik
 
Both versions use OpenGL, but only with 5.6 the interaction performance is poor.

So far I've tried static mappers and/or immediatemoderendering with little success. Right now I'm looking for a way to file an example that I can provide to those willing to look at it. OpenSceneGraph sounds interesting.

Regards
Martin

Von: "Björn Zehner" [mailto:bjoern.zehner at ufz.de]
Gesendet: Dienstag, 28. September 2010 18:00
An: Affolter Martin
Cc: vtkusers at vtk.org
Betreff: Re: [vtkusers] How to visualize thousands of actors with good performance

Hello Martin,
 
how many thousands of actors do you have? I am asking because rendering performance is not only limited by the number of vertices and triangles you have but by the number of objects too. This has more to do with OpenGL than with VTK. I think this is explained in more detail in:
"Cebenoyan, C. (2004): Graphics Pipeline Performance. In: GPU Gems, Edited by Randima Fernando, Addison Wesley, Boston"
I believe that NVidia has made this available online.
 
If this is your problem, than you need some datastructure that allows to efficiently cull away the objects that are not visible (e.g. a quadtree). Are all objects (vtkActors) visible at the same time? If yes, you might need to make some assumptions, such as that the users can only pick objects that are near, and combine these culling techniques with Level Of Detail techniques. I am not sure if such an implementation can be done with VTK, may be you need a scenegraph that is targeted at rendering, such as OpenSG or OpenSceneGraph.
 
Kind regards,
Björn Zehner
 

-------------------------------------------------------------------------
Dr. Bjoern Zehner
UFZ Centre for Environmental Research Leipzig-Halle
Permoserstrasse 15
04318 Leipzig
Germany
http://www.ufz.de/index.php?en=5673
Tel: ++49 (341) 235 1979
Fax: ++49 (341) 235 1939
_______________________________________________
Powered by www.kitware.com

Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html

Please keep messages on-topic and check the VTK FAQ at: http://www.vtk.org/Wiki/VTK_FAQ

Follow this link to subscribe/unsubscribe:
http://www.vtk.org/mailman/listinfo/vtkusers