[identity profile] call-waiting.livejournal.com 2008-07-16 10:26 am (UTC)(link)
The wiimote is based on accelerometers, so it has several aspects that mean it's not precisely 1:1 spatially. The initial orientation and position of the wiimote relative to the wii can't be established precisely, and because the current positions and orientations are calculated as the path integral of the physical quantity that's *actually* being measured, errors will accumulate and so the calculated position will drift over time. I'm sure the wii probably uses heuristics of some sort to account for this in the current wiimote.

Certain other forthcoming 3d controllers are 1:1 from the get-go.