I can't say what the problem is, but I doubt it is PolygonOffset. On my own PSSM implementation and other simpler shadows that I have done everything works well with factor = 1.1 and units = 4.0. These numbers come straight out of this document: http://www1.cs.columbia.edu/~ravir/6160/papers/shadowmaps.ppt
Numbers as large as 10.0/20.0 really shouldn't be necessary, and I've never heard of using negative numbers for PolygonOffset. That's a new one on me. Anyway, I believe the problem lies somewhere other than PolygonOffset. -- Terry Welsh - mogumbo 'at' gmail.com www.reallyslick.com | www.mogumbo.com > Message: 8 > Date: Thu, 27 Sep 2007 13:41:51 +0100 > From: "Robert Osfield" <[EMAIL PROTECTED]> > Subject: Re: [osg-users] ParallelSplitShadowMap .... > To: "OpenSceneGraph Users" <osg-users@lists.openscenegraph.org> > Message-ID: > <[EMAIL PROTECTED]> > Content-Type: text/plain; charset=ISO-8859-1 > > Thanks Adrian, > > Changes now merged and submitted to SVN. > > Visual quality is better with the suggested options in the README but > still not great, in particular I loose shadows when near to objects > and at shallow angles to the surfaces under shadow. I've played > around with the polygonoffset and found that changing units makes no > difference for the models/views I've tested, but factor to to 4 or 5 > seems sufficient to avoid the z fighting. The values you've chosen > for NVidia look excessive. > > I am beginning to wonder about the value of using PolygonOffset in > this context, its just not reliable enough across hardware. > Alternatives to using PolygonOffset are tweaking the depth range via > osg::Depth or via a small tweak to the projection matrix. Replacing > osg::PolygonOffset by osg::Depth might well be a useful thing to try. > > Robert. > > On 9/26/07, Adrian Egli <[EMAIL PROTECTED]> wrote: > > Hi Robert, > > > > please update the PSSM, i did some bug fixes and added new features to move > > the camera virtual against the view direction by applaying a simple distance > > factor (a), which is calculated camera eye - camera center distance. and we > > can move the "light camera" against the light direction (b). > > > > (a) some objects behind the camera can cast shadow > > (b) object aboive the camera can cast shadow > > > > then i fixed the shadow map orientation, now screen x coordinate alinged > > which improve the quality > > > > /adegli > > > > -- > > ******************************************** > > Adrian Egli > > _______________________________________________ > > 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
