Hi,
ran into something lately,which,from my point of view at least,may well be
a little fault.
Look here,in particular where the arms of the cross meet the surface of the block.
[attachimg=1]
The higher the sun the less visible the effect.
With the sun on the opposite side something strange shows up,too.
[attachimg=2]
Varies with sun elevation also.
When the render has stopped and the 'after-render-calculations' start anything
looks as it should,but on finishing the render it pops up.
[attachimg=3]
This effect shows up with different models and setups.Tested with separate
pieces of geometry penetrating each other,with separate pieces on top of
each other and one piece geometry,but alas...