Glass material on single plane - normals problem

[tricky]

I have some window glass which is simply an imported series of rectangles from Autocad that I then put a 'Surface' modifier on in order to turn them into...well...a surface. The rectangles are all parts of Autocad blocks - some of them are mirrored blocks, some of them aren't. When I apply a simple glass material to them all (255,255,255 in reflection and ticked falloff, 250,250,250 in refraction), the mirrored block glass is darker.

It is something to do with normals.

What is the easiest way to solve this? I guess I could put a shell modifier on there, but I didn't really want to add extra geometry.

[Bruce Hart]

You could perhaps use a mesh select modifier to convert these shapes to a surface instead (less memory overhead possibly). As an edit mesh you have the option to "show normals" which may reveal which ones are facing the wrong way. If you're lucky Unify Normals could fix the lot?

[tricky]

You could perhaps use a mesh select modifier to convert these shapes to a surface instead (less memory overhead possibly). As an edit mesh you have the option to "show normals" which may reveal which ones are facing the wrong way. If you're lucky Unify Normals could fix the lot?

Good suggestion. However, I am file linking these lines from Autocad, and as soon as you apply an edit mesh/poly/spline type modifier, the file link brakes (i.e. updates to the blocks in the autocad model are no longer updated in the max file). You can apply sweeps, extrudes and things like that, but not 'edit' modifiers.

Maybe I'll try a shell modifier.

I'm just suprised this isn't a simple Vray '2-sided' material issue though.

[vlado]

If the windows are just a simple plane, you could try a VRayMtl material with the following settings:
*) diffuse - black
*) reflection - falloff map
*) refraction - white or tinted as you wish
*) refraction IOR - 1.0
*) reflect on back side - enabled

Best regards,
Vlado