[osg-users] Black stains in my rendering?

Antoine Rennuit antoinerennuit at hotmail.com
Tue Jan 23 04:44:24 PST 2018

Dear forum,

I have a OSG app which I have been using for a while to display complex meshes, grids, widgets... Now I am displaying a NURBS surface (well it is also seen as a mesh to OSG) which is the result of a points cloud fitting and I observe dirty black stains on the normally smooth grey surface that is drawn. You can observe them on the image below.


Now I have checked with the OSG default shading and with my own custom Phong shading and both methods return the same black stains.


I initially thought that it was due to my surface being slightly rippled itself (it should not be rippled but that could have been a bug explaining the behavior observed in my rendering), but it is actually not rippled at all, as seen on the normals rendering below and where all the normals are cleanly aligned (except in the bottom right where the geometry is no longer planar - which is expected according to the fitted points cloud).

Any idea of where these dirty black stains could come from?

Thanks a lot,


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