Thanks Dave,

I am thinking the inner glow style could also be used with a bump to give the illusion that the wires had thickness. But, I was playing with the transparency map texture approach and it does not hold up well for long shots. It becomes barely visible.

It really needs thickness and although the poly count is lower 1 poly vs 18k for an accurate model of the grate the render times are within 1 sec and for close shot the surface beats the texture.

So for the best renders I think modeling the surface is better unless there is a way to add thickness to the transparency map which I have found no easy way to do in maya.

What would be nice is being able to apply both displacement and transparency (as I have seen done in rhino with vray it was very impressive). Using a texture for applications like this has an advantage that you can easily change the pattern, rotation, repeat, offset of the grating.

Anyway it was fun exploring the transparency approach and it could have some applications although I lean towards a modeled surface for the best looking renders.