February 08, 2012, 11:21:57 pm
I think Brian's solution with metal reflective surface looks better and will handle a non-static scene as well, must try that out.
Anyway, here's how I did it:
1. place your mirror or mirror surface where needed or as part of import objects, preferably have an additional forward glass object or coplanar surface
2. place your camera for a single shot where the mirror is and take a shot looking out from the mirror and render to photo
3. flip the image horizontally to match as the mirrored perspective
3. apply the camera shot render image to the surface of your mirror, the main mirror surface, not the glass surface
4. scale and position it as needed in the Material editor depending if the surface UV's are Ok for it or not
5. apply a glass material to the glass surface, if it's suitable for the scene and not otherwise needed then also use the Utilities -> Reflection Control to tweak local reflections for the glass.
6. thats about it.
Very fake looking reflection, used to use it in realtime 3d when needed, possibly tweaking the image in PS to give it a slight curvature or other might help.