and give that strange result for all types of ligh (e.g. sun, lamp, etc) when ray shadow used, and give right result for buffered shadow or shadow turned off.
Depends of camera position this artefact can different kind:
I’ve had this problem before. The faces on your mesh are so close together at such a fine resolution that the camera is having trouble distinguishing between them. Move the camera even a little and the abberation is fixed. To solve the problem you’ll likely have to either add more distance between the faces or remove one or the other. You might try scaling up too, but I believe that’s the problem. The matter was reported to the bug tracker and was determined to be a non issue so you’ll have to work around (if, in fact, I’m right about what’s going on).
And so, there is an another way to fix it: Just a make camera Clip start and clip end distance less. And its work too, but unfortuntly not so helpful.
Biasing problem still chase me. When meshes are near each other somethimes its rendered wrong. Some meshes could placed in wrong z-order. I dont know why.
Is there any way to make much or less precision for the rendering? it would be great.
Yes, didn’t think of that. Most settings of that nature in blender allow you to go beyond the optimal to a point that will cause artifacts. Set the bias up from 0, good idea. Have to remember for the next time.
Sorry, bias is for shadow mapped lamps. In lamp properties. Camera is clipping. Set clipping up to .1 or something is what you were saying right? In the camera properties F9. My error. Apologies.