Re: [osg-users] PagedLOD - too many nodes
Hi Robert, However, I think this is probably just a hack around what it essentially an issue of poor load balancing in the paged database you have built. In essence what you are trying to do when using LOD/PagedLOD's is to keep the load on the whole computer to a level that the system can handle it comfortably I hope my scene is well balanced. To be exact - The scene is forest of 6 binary trees, where each node has Geode with maximum N vertices (ie very similiar size, mostly N). I am not using octrees (mentioned as example), but tetrahedra 3D space division. The parent node is 50% simplification of its two children. So, one pagedLOD has a geometry of size N and reference to the file, where is group of 2 pagedLODs, each having geometry of size N, together representing higher resolution of parent geometry. It is implementation of Adaptive TetraPuzzles approach (http://www.crs4.it/vic/data/papers/sig2004-tetrapuzzles.pdf) It's clear, that the goal is to handle constant number of nodes in memory and on-screen. My question is, how to find the number since it is hardware dependant. Do you think the idea of catching out-of-memory error is a good way? Even if I set the max. number of nodes (=geodes, polygons on screen) manually, how to manage this? By implementation of some logic in osgDB::Registry::ReadFileCallback? I think the OSG_MAX_PAGEDLOD in conjunction with adjusting pagedLOD::setRange can do very similiar job. Maybe with an restriction, that no more than OSG_MAX_PAGEDLOD pagedlods will be loaded? If you think that the model is cube and the multiresolution tree is built on the surface, then the tree is good balanced and the only one criteria for correct visualization is, when high-res chunks (tiles) replace the low res ones. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=33019#33019 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
[osg-users] PagedLOD - too many nodes
Hi, I am using osg::PagedLOD nodes in my project for large models visualization. The model is splitted into several parts (like octree) and multiresolution tree is made - same as VPB uses: Code: Group PagedLOD child 0 - local tile geometry at low resolution child 1 - external file reference PagedLOD child 0 - local tile geometry at low resolution child 1 - external file reference I understand the system of unloading nodes by DatabasePager, when PagedLOD nodes count is bigger than OSG_MAX_PAGEDLOD (I hope that unloaded pagedlod nodes unload also corresponding data on GPU - when using VBO) The system works fine, but the problem is in good PagedLOD::setRangeMode and PagedLOD::setRange (between lower res. geode and external reference) data setting. Since my model is not terrain, definition of setRange value is crucial. I use PIXEL_SIZE_ON_SCREEN metrics and by low setRange number the high resolution files are requested, high number of Geometries is loaded and openGL out-of-memory occurs and no new nodes are loaded. The setRange number depends on graphical window size, GPU memory, so it should be calculated somehow - to get the best performance from hardware. Does anyone have tip how to dynamically adjust setRange values? Or is any better technique with different metrics? I have an idea to adjust setRange (or change LODScale) when an out-of-memory openGL error occurs. Then I would change the setRange value (it is same for all pagedLOD nodes), free the GPU memory and load again. What do you think about this idea? How do I free occupied GPU memory? Is is enough to reconnect the subtree from scene? How do I catch openGL error? Could culling settings help here to have smaller scene? Culling in my app is set to OSG default. Many thanks in advance, Tomas -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=33000#33000 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] PagedLOD - too many nodes
Hi Thomas, It's possible to adjust the children selection dynamically by adjusting the Camera::LODScale via viewer.getCamera()-setLODScale(myScale);. However, I think this is probably just a hack around what it essentially an issue of poor load balancing in the paged database you have built. In essence what you are trying to do when using LOD/PagedLOD's is to keep the load on the whole computer to a level that the system can handle it comfortably. Think about trying to aim for a constant number of nodes in memory and on-screen, and constant number of polygons and textures on screen, we can never attain this exactly but this is the goal of load balancing. Using of PagedLOD over LOD allows you to scale higher as you are no-longer limited by main memory, however, you can still easily build databases that are too big even for runtime use - if this is the case then you either have to simplify the children at each LOD range or make the LOD's ranges more conservative. With an Octree the potentially for an explosion of nodes and complexity of the scene is pretty high unless the Octree is sparse, this keep balancing the books you will have to be prepared to be quite conservative with your range settings. There is of course often other ways to solve problems. Perhaps some other type of rendering/scene graph approach can held lower the load, this needn't be in place of paging. What other techniques might appropriate I can't say as I know close to nothing about your application and the type of data you are trying to handle. Robert. Robert. On Fri, Oct 22, 2010 at 5:41 PM, Tomas Hnilica tomas.hnil...@webstep.net wrote: Hi, I am using osg::PagedLOD nodes in my project for large models visualization. The model is splitted into several parts (like octree) and multiresolution tree is made - same as VPB uses: Code: Group PagedLOD child 0 - local tile geometry at low resolution child 1 - external file reference PagedLOD child 0 - local tile geometry at low resolution child 1 - external file reference I understand the system of unloading nodes by DatabasePager, when PagedLOD nodes count is bigger than OSG_MAX_PAGEDLOD (I hope that unloaded pagedlod nodes unload also corresponding data on GPU - when using VBO) The system works fine, but the problem is in good PagedLOD::setRangeMode and PagedLOD::setRange (between lower res. geode and external reference) data setting. Since my model is not terrain, definition of setRange value is crucial. I use PIXEL_SIZE_ON_SCREEN metrics and by low setRange number the high resolution files are requested, high number of Geometries is loaded and openGL out-of-memory occurs and no new nodes are loaded. The setRange number depends on graphical window size, GPU memory, so it should be calculated somehow - to get the best performance from hardware. Does anyone have tip how to dynamically adjust setRange values? Or is any better technique with different metrics? I have an idea to adjust setRange (or change LODScale) when an out-of-memory openGL error occurs. Then I would change the setRange value (it is same for all pagedLOD nodes), free the GPU memory and load again. What do you think about this idea? How do I free occupied GPU memory? Is is enough to reconnect the subtree from scene? How do I catch openGL error? Could culling settings help here to have smaller scene? Culling in my app is set to OSG default. Many thanks in advance, Tomas -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=33000#33000 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] a ; too many
Thanks for reporting this Anders, this. The ; was indeed erroneous,
fix a bug, introduce a bug... I've now removed the ; and checked in
this fix.
On Feb 19, 2008 2:52 PM, Anders Backman [EMAIL PROTECTED] wrote:
When I build osg from svn today I got the warning:
.\ParticleSystem.cpp(187) : warning C4390: ';' : empty controlled statement
found; is this the intent?
Looks like a feature to me.
if (currentParticle-getShape() != startParticle-getShape());
{
startParticle-endRender();
currentParticle-beginRender();
startParticle = currentParticle;
}
/Anders
--
Anders Backman Email:[EMAIL PROTECTED]
HPC2N/VRlab Phone:+46 (0)90-786 9936
Umea university Cellular: +46 (0)70-392 64 67
S-901 87 UMEA SWEDEN Fax: +46 90-786 6126
http://www.cs.umu.se/~andersb
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[osg-users] a ; too many
When I build osg from svn today I got the warning:
.\ParticleSystem.cpp(187) : warning C4390: ';' : empty controlled statement
found; is this the intent?
Looks like a feature to me.
if (currentParticle-getShape() != startParticle-getShape());
{
startParticle-endRender();
currentParticle-beginRender();
startParticle = currentParticle;
}
/Anders
--
Anders Backman Email:[EMAIL PROTECTED]
HPC2N/VRlab Phone:+46 (0)90-786 9936
Umea university Cellular: +46 (0)70-392 64 67
S-901 87 UMEA SWEDEN Fax: +46 90-786 6126
http://www.cs.umu.se/~andersb
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