View Full Version : Noise and flicker problems

09-07-2005, 06:35 AM
I need some help fixing some noise flickering issues with a scene I am working on.

Some strange flickering patterns appear in reflections, highlights and complex areas. Camera is the only animated object. I have tried to push up the AA and used different Reconstruction Filters. But that has not solved the issue.

The most problematic areas is simple "Box houses" with painted texture maps. Color, Spec, Reflection and Bump. (Can be seen at the far end of the street)
But a slight noise also appear at non textured (but complex) models.
At first the street ground had procedural texturing but this beacame a mess of noise and flicker...removed that for now.

The render is PAL cropped down to 720x390. I have tried to render out a 200% version and scale it down in post. I does not help.

Here is a link to a few frames from the animation.

6 Frames quicktime example (http://www.parolofsson.se/noise-flicker.mov)

I really hope you guys can give me some ideas on this.

09-07-2005, 12:40 PM
I have gotten this before with non-planar polygons and polygons on top of one another. Two thgings to check.

09-07-2005, 02:21 PM
For your painted textures, try various settings in "Mipmap Quality" and "Mipmap Strenth" in the Texture Editor or Image Editor. This was called Texture Antialiasing in prior versions, and is intended to try to reduce the moire patterns.

For complex geometries with a lot of repeating layered structure, moire patterns may be natural, and would be a correct rendering "artifact" (i.e. you'd see them with your own eyes). If it's really distracting, you may need to use alternate geometry when they're in the distance.


09-07-2005, 03:20 PM
Any of the above can be a problem but - What are your AA (antialiasing ) settings now? Crank them up AA 7 to 9 passes min. Yes it will kill your render times but when you have very fine details like that you have little other choices.

09-07-2005, 03:37 PM
When you have so many parallel lines near vertical you're going to have this problem, you can even see this in real video, it's called the moire effect. It wouldn't surprise me if you had to use Extreme AA. Also, use Enhanced and turn off Adaptive sampling.

For distant buildings, replace geomtery with images of the geometry, that will help too.

Looking really nice by the way.

09-07-2005, 05:30 PM
maybe a bit of DOF would fix this or fog.

It realy looks like multiple polys sharing the same points to me.

If all else fails I would bake the scene, then turn of all the lighting stuff and render really huge, with alot of AA.

looking great despite the flicker.

09-08-2005, 10:16 AM
Thanks for the help!

I have pushed up the AA to PDA-17 and changed the Mipmap strenght from 1 to 3 on most textures. I also used the Mitchell (soft) option. This have eliminated alot of the flicker/noise in the scene. Even the houses with high poly detail.

I am now moving on with this scene, calling this problem Solved! At the stage of final render I will push the AA even further to maybe PDA-21 or higher to get even better result.

09-08-2005, 10:58 AM
Or dump PLD altogether for a better result in less time.

Do a test with some fine lines at maximum AA. Classic extreme AA will look better than PLD-35, and it's faster too.