[wahn]

Hi,

While doing some tests where I look from outside through a double-winged (glass) door into a room I came across something funny. Both doors wings are basically the same but I used groups in Maya to mirror the geometry along one axis. If you use a dielectric material for the glass the normals get flipped automatically by the mirror transform (e.g. scalex = -1). That way I ended up with a "magnifying effect" on the one door wing where the other one looked as I expected. Well, the solution is to flip the normals BEFORE the mirror transform kicks in. If you forget that Maxwell will assume the the camera for the one door is already in the glass, enters empty space within the glass, and enters a solid glass block within the room. Physically that's impossible (that the camera is on the right part of the image within a glass block and one the left side it's not). Anyway, normals are funny ... Does anybody remember that Blender scene with an "Escher" effect? You see half of an colonnaded temple from "half below", the other part from "half above". That scene was modelled in 3D but used "weird" normals which made the one sided geometry render the inside or outside of e.g. a column ... Anyway, I just thought I let you know about my "funny" experience and how to avoid that effect

Cheers,

Jan