Coordinate Systems, Standard Units
The default coordinate system is a cartesian, right-handed,
3-dimensional coordinate system. By default, objects are projected
onto a 2-dimensional device by projecting them in the direction of the
-Z axis, with the positive X axis to the right and the positive Y axis
up (a camera or modeling transformation may be used to alter this
default projection, of course).
The standard unit for lengths and distances specified in the metafile is
meters. The standard unit for angles is radians.
--- The current VRML spec assumes that Y is up. That should be stated explicitly; it is an unfortunate oversight. The descriptions of Perspective and Orthographic cameras, and all of the primitive shapes would have to be changed if the up direction isn't Y. Since no amount of arguing is going to resolve this issue, I suggest we take the easy way out and use the conventions described above (Y up, Z is out, distances are meters, rotations are radians) that are implicit in the existing VRML spec. And to avoid rehashing this issue in the future, we should add the above description to the VRML 1.0 spec.