Rendered view breaking up? Rhino 4

[Fred_C]

@LyndaM
It appears to be ‘z-fighting’ (two surfaces in the same place) described here:

Display Conduit Object Not Always "Good"

This looks like a case of “z-fighting” to me, i.e. two surfaces are in exactly the same location, so the drawing code can’t really decide which of the two surfaces to show, resulting in this kind of interesting patterns. You may want to offset your geometry a very tiny amount away from the surface (towards the camera) to get rid of the fighting effect. /Nathan

edit: maybe hide/delete the duplicate