Mental Ray Moire

[Falam]

Moire in Rendering, how can I fix this ?
My AA settings are 2/2 (min/max) and sampling contrast is set to an extremly low setting. I've tried most Filter settings, I've searched and it is a common problem, yet so hard to fix !

[Letterbox]

depends on many things, so first you might have to up/lower the settings more. try AA 1/4 (it might warn don't worry), and SC do to as low as 0.005. Look at the quality of the texture? The size of the texture? Or are you using a procedural? Have you looked in the texture ppg and the settings in there? Lots of possibilities with out more info on how scene is setup, the above should help, so try them all out in combos methodically till you get where is it, THEN you can look at what you can adjust to increase the rendering performance without sacrificing quality.

[Kzin]

try to use inified.
also, did you use map format for your textures? map files using mipmapping and you can also use additionel filtering if need. directly thru impf_copy command or thru the image clip nodes, the elliptical filtering feature under the image filtering tab (but deactivate bilinear interpolation).
another way of removing such effects is not to use ultra highres images as textures for small resolution renders.

[Falam]

That is the odd thing, there are no textures on the object. I have my SC down to 0.004 and I've tried AA at 4/4 and 1/3 and the moire doesn't go away, arghhh.

[Kzin]

That is the odd thing, there are no textures on the object. I have my SC down to 0.004 and I've tried AA at 4/4 and 1/3 and the moire doesn't go away, arghhh.

show us the rendertree and the shadersettings.

[Falam]

That is the odd thing, there are no textures on the object. I have my SC down to 0.004 and I've tried AA at 4/4 and 1/3 and the moire doesn't go away, arghhh.

show us the rendertree and the shadersettings.

At this stage, I'm only using an AO shader. Take a look at this region render of the scene, tell me if it can be improved or not ?

[Kzin]

That is the odd thing, there are no textures on the object. I have my SC down to 0.004 and I've tried AA at 4/4 and 1/3 and the moire doesn't go away, arghhh.

show us the rendertree and the shadersettings.

At this stage, I'm only using an AO shader. Take a look at this region render of the scene, tell me if it can be improved or not ?

you have jitter off but it should be on. the samples will then placed more randomly. but as i wrote, try to use unified. and for filter, dont use mitchell. mitchel will slightly sharpen your image which will make your problem more worse. best is to use gaussian with filter width of 2 or 2,25 or 2,5.

[gustavoeb]

Have you tried eliptical filtering?
http://elementalray.wordpress.com/2012/ ... ental-ray/

[Falam]

It is better, here is what I'm working on; It's part of a bigger scene, the rest I have to finish after I finish this.

[nas]

Try rendering it double resolution, but don't keep the same settings obviously. Doubling the amount of pixels a texture has to operate in helps with moire.

[Maximus]

You shouldnt use any other filter than Gaussian. Try to switch to gaussian 1.7 or 1.8 and see if it goes away.
Mitchell filter produce pixel data which might end up in errors like this (also you using a value of 5 which is a lot), while gauss is the most correct filter to use.
Also as kzin said use unified, it helps a lot to pickup all the details in scene. start with min 1 max 100 quality 2 and see how it goes.

[ActionArt]

This may not be so much of a rendering problem as an optical problem. Even a digital camera shooting a physical object of this nature can produce the same results. It's a result of square pixels used in render engines, image sensors and display devices. Fiddling with AA settings may not help much.

First thing I'd try modifying your floor grating a bit. Try beveling and rounding the edges, even if it's a small amount. This gives the render engine something other than a hard edge to work with. Perhaps break up the very orderly grid pattern with bump and specular maps even if they're very subtle.

As for render settings, extreme low thresholds and high sample rates likely won't help much. For hard edge objects like this I've found these settings to work best (just personal experience, not proven in a lab):

Sample contrast around .075 (no need to overdo it, it won't help).
AA sampling, Min 0, Max 2 (more won't likely help)
Primary rays to raytrace (not scanline) (sometimes the depth sorting in scanline isn't exact enough)
Filter set to triangle, size 2, jitter sub pixel samples on. I've always found this to be the best for stills like this.

Unlike others, I've had no good results from unified sampling, especially on hard edge scenes like this, not sure why. As mentioned above, you may well get better results from higher-res and then sizing down if needed. Of course a little DOF in the final render could help a lot too.

Mainly though, I think modeling in some edge detail (mainly rounding) would help the most. Good luck ;)

[Rez007]

I think you are going a little extreme on some of your values. If you want to use AA (I prefer to use Unified as of now), but if you want to do it, I tend to use the values close to what ActionArt mentioned:

Primary Rays = Raytrace
Min/Max = 0/1 to 0/2 to 1/2...and so on... (basicaly x/(x+1) or x/(x+2)) Note: One thing I noticed in your settings is that you sometimes use the same value for your min/max - you should avoid doing this...Mental Ray needs different values as something for it to anti-alias against...I believe this is written in the doc files for Mental Ray.
Filter = Mitchell 4 (I personally never use guassian as I feel it produces blurry renders...)
contrast = 0.05 for all (this number seems to work good for me)

The link that was posted for eliptical filtering seems like it would do the trick, but then again I believe you said you had no textures...maybe the part that Action mentioned might work best - higher DPI/PPI would help in your case.

I dont run into this problem too much, but it can be a pain - best of luck and please let us know what worked best for you.

[Kzin]

Mitchell filter sharpens the image, means it would make the problem more visible. If you want sharpen renders, use gaussian with 2 or 1,8 for filter width.

[Rez007]

Mitchell filter sharpens the image, means it would make the problem more visible. If you want sharpen renders, use gaussian with 2 or 1,8 for filter width.

That would make sense for his case...I will have to give that gaussian a try again with the settings you mentioned - that might work pretty well. I just haven't used gaussian for a while now since I thought it usually came out blurry. Thanks for the tip.