2008/7/29 Jean-Sébastien Guay <[EMAIL PROTECTED]> > Hello Dan, > > I'm looking at shadow techniques provided by the osgshadow nodekit for use >> in a production project. On the wiki it reads like only ShadowMap is >> production >> ready and all the others have problems. Is this the case? Or have the >> others >> been marked as experimental because they do not work across video cards? >> > > Here is my opinion on the current shadow techniques in osgShadow. Please > take these with a grain of salt. And bare in mind that it's pretty easy to > compare them yourself in your environment, because in most cases once you > have one shadow technique running you can just swap out the ShadowTechnique > that you give to your ShadowedScene for another one. Some tweaks are > technique-specific but that will give you a good idea of what they look like > in your context. > > > osgShadow::ShadowVolume is broken, I have never seen it work correctly even > with simple test scenes. There are inverted shadows everywhere (which hints > at a problem with the z-pass or z-fail implementation). If someone wants to > fix it, it would be a nice alternative to other techniques in some > situations. > > osgShadow::ShadowTexture is the simplest technique. It works well for > planar shadows, but for anything more complex you'll want at least > osgShadow::ShadowMap. > > osgShadow::ShadowMap is what I would call the main workforce of osgShadow > at the moment. It works well, is well tested, and is flexible. The only > downside is the heavy shadow map aliasing you get on medium to large > environments, but this is to be expected from a simple technique like this. > It's really just the basic shadow map, no bells or whistles. > > osgShadow::SoftShadowMap is ShadowMap augmented with a simple filtering of > shadows. The look is not too realistic (it smooths everywhere uniformly > instead of considering distance of occluder for the width of the penumbra, > which would be more complex of course) but it alleviates the aliasing > problem somewhat. It can still only go so far if the environments are large. > > osgShadow::ParallelSplitShadowMap is the first of the "next-gen" shadow > mapping techniques integrated into OSG. Essentially, it uses several shadow > maps and is view-dependent which reduces aliasing dramatically. It's less > tested, and until recently was completely broken. It now should work on most > machines, but I'm still not confident enough about it to use it in > production (my personal opinion - try it out and see for yourself). >
Parallel Split Shadow Map: it's still under *beta* release :-) i wait for a review by a specialist, ... please review, test this algorithme, for terrain, ... it's once of the most robust algorithm, but it has to be tested. *** > > > A few more techniques will soon be added (shortly after 2.6, hopefully) > which are also view dependent, and will give some more choices to users. > Essentially a shadow technique is a tool, and you just have to find the > right one for your needs. > > If the wiki misrepresents this state of affairs, could you please update it > or post the pages where there is outdated info here? > > Hope this helps, > > J-S > -- > ______________________________________________________ > Jean-Sebastien Guay [EMAIL PROTECTED] > http://www.cm-labs.com/ > http://whitestar02.webhop.org/ > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > -- ******************************************** Adrian Egli
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