Thiago Bastos
Wed, 07 May 2008 06:56:33 -0700
Hi all, Our project has been using OpenSG 1.8 for eight months (thanks btw!). Everything was fine until now, when we finally got to create a really large scene, with objects at very different scales (say, a country-sized terrain, geological data, and buildings with small objects). Our coordinate system is in meters. The diameter of our scene's bounding box is now close to 10^7. Some objects are located very far from each other. The main problem we are experiencing is spatial jittering (and consequently, severe Z-fighting) due to the lack of precision in 32-bit floats. We also had problems with the default OpenSG navigators (probably due to a very large scene bbox), but that's secondary. We just can't find a good solution to the spatial jittering problem. I've already done a decent amount of research. I also searched this list and found the wiki page http://opensg.vrsource.org/trac/wiki/HDI/HugeScenes - but it was not terribly helpful. It seems that our problem would be solved if we could use double-precision floats for the camera; or have a DoubleTransform somewhere in the scenegraph, and have the render traversal accumulate the matrices using double-precision. For instance, this kind of support has been part of OpenSceneGraph for quite some time. It seems you have already considered adding DoubleTransforms to OpenSG, but later the idea was dumped. I must ask: why? If you don't think DoubleTransforms are really important, do you know any other decent way to solve our precision problems? Thanks in advance. -- Thiago
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