Standardizing coordinate systems, units of measure

Gavin Bell (gavin@krypton.engr.sgi.com)
Tue, 2 Aug 1994 13:50:29 -0700


I vote for meters being the standard of measure (that is the OI
convention, and works well for most real-world objects). I think
millimeters are too small, kilometers are too big, and not using the
metric system would be stupid.

We should also decide which way is up. I like the OpenGL coordinate
system, which has X increasing to the right, Y up, and Z coming out of
your monitor.

Non-symmetric objects that move should be defined so that increasing
their X position makes them look like they are moving forward. For
example, if modelling a car, the headlights should shine down the +X
axis and if you look out the sun roof you should be looking in the +Y
direction.