Static noice in renders ?

While i was working on a render, and created a preview movie in lower render settings.
I noticed something verry odd, my scene was about a beach with dunes and sea.
The sun moves, and the camera moves, and the sea waves are using the ocean modifier.
I’ll soon post it once the high ress render has finished but the odd thing is the low res render.

So despite everything was moving… i noticed the noise, grain; was static it didnt change at all.
Noise in lower resolutions rendered movies, behaved like a static image overlay.
in fact it seam just a little tiny bit lighter this noise, then the good underlaying render part.

So…it doesnt seam to be some unresolved rays that depend a lot upon objects viewing angle, as it is all static ??

A seccond thought i have then is it “added” ?
Maybe not by purpose, but by some small error/buy coding typo ?

And if the noise patern looks so static predictable, wouldnt it be easy to create some internal anti noise filter ?.
For example blend only the static noise pixels ? (like an anti noise, for flatbad scanners and dead pixels)

Make the noise dynamic, then…:wink:
You can animate the seed value for the noise in the Sampling tab:


If you type #frame in the input box for the seed, Blender will use the current frame number as seed number. The input box will turn to a pinkish colour to indicate the seed is now driven by another value.

You didn’t say for which render engine but I suppose it’s Cycles. That static noise is actually entirely your fault. :wink:

A quick workaround is to type #frame as Seed value so that Cycles doesn’t use the same noise for every frame. (This will create a driver but you don’t have to worry any more about it.) The result of this little trick is that Cycles uses the frame number to generate the noise it needs. Each frame number being unique, the noise is unique too.

Test it, you’ll see the difference very quickly on your dunes of sand. :wink:

EDIT: And Ikari Shinji beat me on the finish line…

No, no you 2 get me wrong.

I know about these tricks and clamp and seed settings animated noise values etc.
The point is, that it is a “static” form of noise, independent of objects or viewing angle or light setup.
It behaves as if it was added as an overlay image.
And thus on that point it could be blended /softened /removed (if it is a bug) etc

The problem with noise (images / audio / TV signal /photo-camera’s / microphones / amplifiers / equalizers, …etc etc…)
Is always that one tries to reduce the “unknown” noise factor, and that is very complex.
One needs very advanced algorithms or electronics who try to filter it out but are never optimal

But in blender it is not “unknown” noise, it is not “unpredictable”.
It is static, and thus it should be solvable be reducible, and be removable; with a good noise filter.
A filter that works on the known pattern
A
s it doesn’t have to predict this pattern in theory also an optimal noise filter is possible.
And as the filter doesn’t have the estimating complexity of random noise such filter might be a pretty fast calculation.

This noise pattern is called Fixed Pattern Noise, and most camera’s use algorythms against it.
Here is an article http://www.dyxum.com/columns/photoworld/Technical_knowledge/Physics_of_noise.asp