Eliminating Moire Pattern - Mental Ray

#1

I’m working on a character that has a tank top. I’m using a normal map for the fine lines that run vertically up and down the tank top cloth. Up close, it looks great with no noise, medium distance just a bit of moire noise, far away it’s way to distracting and the lines become incomprehensible, wavy and distorted. It’s going to be distracting for the final image so I’m diagnosing now how to alleviate the issue now, though I’m not in an imminent rush as there’s a lot left to work on in the mean time.

Tried setting the Filter to Mitchel/Lancos 4. Aliasing Min Max is 0 - 3 with sampling at .05 and it’s just not doing enough.

I don’t mind doing whatever it takes to fix this, so long as it looks good up close and from afar. This includes any render options, additional render time, modifying the texture itself, setting up Mip Maps which so far don’t seem to help at all and even a blurring filter at render or in post. I’ve also tried Image Filtering on the texture map itself, Eliptical filtering, however the only setting that seems to have any effect is enabling the filtering on RGBA, then no matter what setting I fiddle with from there, nothing additional changes. It does seem to help some, but again, not enough unless I can get the options working.

Any suggestions that may help would be greatly appreciated and I will respond with my results of any suggestions as they come. Thank you in advance. -Jet

#2

You can try
-scale down your texture in photoshop, dont rely on automatic mipmaps
-render at double resolution
-render objects with fine textures on separate pass with extremely high fixed AA levels (like 5x5) of course this will make your computer cry
-mitchel or lanczos will make your moire more visible, on other hand gauss or box will make your fine lines dissappear but at least there will be no/less moire or noise.

#3

In my experience elliptical filtering only really works with .map files. I think this kind of makes sense since they have a pyramidal structure to them. Try converting your files to .map and see if that helps make elliptical filtering more effective. AFAIK, autoconverting images to map files at rendertime doesn’t do the trick, so you have to do it from the get to.

Hopefully .map files are working better with 2010 than they were with 7!

It’s much faster than doing more and more samples to the over all image (as I’m sure you know).

Another option is to kind of do a manual, incidence angle/distance map look up in the rendertree with two or more maps (one for the steeper angle that is lower res or blurred and one that is for the “front on” look). I would try the .map file and E. Filtering first!

#4

Did you find a solution?

#5

Working on all the suggestions given so far right now.

Using hand made .map files didn’t have any effect, the filtering is doing the same thing in my scene to the regular .tif image as it does for the .map file.

Gauss 3 is working the best so far, the results are almost passable at this point to be honest now that I’ve taken a break and come back to it, Mitchel and Lancos do appear to make it worse but give a crisper image as PiotrekM described.

My computer doesn’t even budge after a minute or two sitting at 5, 5 anti-aliasing, so thats a no go. Setting it to 3, 3 is a bit slow but it works and it fixed the moire, however! Setting it to 1, 1 works just as well and is quite fast. The result compared side by side is the same and will do the trick. If need be, I can separate out to passes.

I think going with 1,1 AI and a 0.07 Sampling Contrast with RGA elliptical filtering on and either Guass 3 or Lancos 4 should give me the results I need. Thanks guys.

#6

would love to see some screens/renders of this, for my own edification. What ended up working best?

#7

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