[osg-users] ParallelSplitShadowMap ....

Robert Osfield robert.osfield at gmail.com
Thu Sep 27 05:41:51 PDT 2007

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.


On 9/26/07, Adrian Egli <3dhelp at gmail.com> 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
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