Small Dots

[glorybound]

I have a room that has this windows film. The film has these small dots, which I can't get to render without strange artifacts. Any tips?

Here is an example photo



And what I am getting

[Joelaff]

That would be a classic example of moire patterns. You can increase the scale of the pattern, blur the pattern texture, render the entire image significantly larger and then try to scale down in post (though you may still get patterns).

Make sure you ARE using Blur on the textures (don't set the blur to 0.01, which, IMO, you should never ever do anyway, at least for animations-- leave it at like 1.0 or no lower than 0.6 perhaps).

You can try different Interpolation filtering method under the Processing tab of VRayBitMap. Bicubic might help, though I think this is the default for non-HDR images.

Increasing your Min AA to 3 to 8 or higher might help as well to get more camera rays.

Note that if you image is eventually going to be printed on paper through a line screen (standard professional printing) ii could pick up more and different moire patterns at that stage due to the screen used for halftoning the inks. At that stage one could request they try to use a stochastic screening process, which can help a lot.

As a side note, this was one of the coolest intentional uses of Moire patterns I have ever scene:

[Joelaff]

Oh, another thought would be to change your AA Reconstruction Filter (Image Filter in the Render Settings). Try Soften with a radius of, say, 2.98 or 3.98 (if you stay just below the next whole number it has to take fewer samples, so is a hint faster).

If that is too soft for you then try Area with a radius of 1.7 to 1.98 (Area above 2.0 starts to look kind of Box blurred). Avoid anything with sharpening.

[glorybound]

Okay, some great help. I'll see what I can do.