how to create depth in 3d ?
multiple images.. so you're saying that duplicating the same image for left and right eyes and then applying the depth map for each image accordingly just won't work correctly in photoshop or any other program for that matter?
That is exactly what they are saying, and they are 100% correct. There is no simple way to do fake 3D that doesn't look utterly fake. Most of the difficult ways also look fake.
when a movie is converted to stereo 3d are they not simply duplicating and applying depth maps to the same single track?
No they are not. That's why good post conversion is so, so expensive. It actually takes lots of human artists to basically clone in those occluded background areas. If the camera is moving, they can sometimes go a few frames forward or back to pick up backgrounds, if the camera is locked down, it's even more difficult.
The 3D re-release of Jurassic Park is a wonderful example of just how well post conversion can be done.