Moire problem on mesh building facade

linea

Hi

I need to depict a very fine exterior facade mesh known as Stamisol - see pictures below (the copper mesh is what we are using, the building pic is an example). The mesh we are using has holes that are just 1 millimetre sq. Obviously in Sketchup the moire is impressively psychedelic. So I need to render it, but KT moires too. Is Kt not up to it? I have tried actually modelling the mesh as opposed to using a png, but both moire. Through work I have access to Vray if that is a better option. I can also use 3DS Max.
Or would I be best just faking it in Photoshop? Ideally though I would like to do something accurate as we would like to be able to get an idea of how much light permeates through the mesh. Failing that, a cosmetic solution would be nice. Thanks in advance.

sepo

I think you will find with most of render engines that mesh is to fine and it wil create moire. The trick is to render really large images. Other way is to do pp in Photoshop but that could bring other set of problems like shadows.

mirjman

here's a trick i use to avoid problems like that:

in photoshop copy the image into a new layer

apply gaussian blur to bottom layer, the amount is a judgment call, but enough to get rid of the moire

apply a mask the top layer, and erase with a brush that has a low opacity to it, this will partially reveal the blurred image below combining the general texture with the detail of the top layer

linea

Thanks Mirjman, sounds like the answer, I'll try that.

I've ran it through Piranesi today too at a friends practice, the png causes no moire at all so that is another potential solution.

Anssi

There are a couple of issues here.

For the exterior photos you can just set some transparency to the material. I once did some facade parts in perforated steel with holes as small as these, and I can honestly say that from a distance it looks like a flat sheet with transparency.

But I want to add a word of caution about moiré: In real life a perforated see-through surface can be quite a dizzying experience when viewed from inside and from near. I once covered a fire escape stair like yours with a perforated corrugated metal sheet to protect it a little from snow, and from the inside it was headache-inducingly psychedelic. I am happy that the stair is not used daily (although I fear the users go there to smoke on the landings as it is prohibited inside)

Anssi

david_h

From the photo, it looks like this could approximated with SU by using a textured material, like a textile and making it transparent. Could that work?

Or you could just tell your boss to use a different material on the building>

linea

Anssi, wow that is interesting, so you would actually see moire in the real world? Thanks for your help.

David, I hoped to approximate it with something but it is impossible to avoid the moire in SU if the texture is at the right scale.

remus

Yes, moire is a real world phenomenon as well. It has something to do with interfering patterns (like offset grids.) http://en.wikipedia.org/wiki/Moire