November 14, 2011, 11:07:09 am
Excerpt from other threads:
Polygons that flicker when they're close to each other (Also known as z-fighting) are caused by the lack of accuracy in real-time 3D, and is present in most 3D engines/modellers that I know of. The bigger the world is and the further away from 0,0,0 you are, the more prevalent the problem is (It's essentially caused by only having 8 digits for polygon positions at our disposal).
1) Depth Offset: If you're doing a real-time walkthrough, you should apply a Lumion material to the flickering surface and adjust the "Depth Offset" slider for the material just enough to get rid of the flickering (press shift while adjusting the slider to do this more accurately).
2) Camera Clip Planes: If your output is a movie clip, there's a very effective way of getting rid of flickering polygons. In the Movie editor, select the clip followed by New effect -> Scene effects -> Camera Clip Planes. Adjusting the "Near" plane slider should eliminate the flickering completely in that clip. If your camera moves around a lot during a clip you will often have to animate the "Camera Clip Planes" effect. Move the time slider to a place where you notice flickering, adjust the "Near plane" slider until the flickering is gone and click on the small circular button to the right of the slider to set a keyframe.
The rule of thumb is that the closer the "Near plane" is to the eye position and the greater the distance between the "Near" and "Far" camera clip planes is, the more z-fighting you're likely to encounter.
In real-time 3D, the distance where z-fighting begins to occur also depends on the distance from the camera to the polygons in question. If the polygons are close to the camera, z-fighting only occurs when the polygons are, say 1mm from each other while at a distance of 2km from the camera it occurs when polygons are, say within 1m of each other.
