Re: Coordinate system

Jan Hardenbergh ([email protected])
Mon, 22 May 95 11:03:00 E


> From: Michael Pichler <[email protected]>
> >>>>> "R" == Randy Stiles <[email protected]> writes:
> R> 1) The base coordinate system should be in the VRML standard, not
ad-hoc
> R> 2) +Z should be up from ground plane, NOT into the screen
> R> 3) X-Y should define the ground plane
> R> 4) Should use the right hand rule

> Have I overlooked something? I thought the VRML spec (maybe somtimes
> not clear enough) defines a right handed coordinate system with a
> horicontal x-z-plane (x to the right, z towards viewer) and the y axis
> pointing upwards. For example the fields of Cube (x=width, y=height,
> z=depth), top/bottom of Cylinder, and the default cameras, looking
> from (0, 0, 1) horicontally into the world make that clear.

This is a good point: the cube clearly is designed and named for the
viewer to be looking at the horizon. Also, the example, "Sample.wrl"
shows a "world" with the X-Z plane as the floor.

Since this is a source of confusion and it is a matter of interpretation
I think it is worth clarifying in the 1.0 spec.

The question is how?

It seems most people would like to create worlds as they would lay out a
map - (X == latitude, Y == longitude, Z == elavation)
The default camera would then give the god's eye point of view.

The cube would be a little inconsistent.

What is the mind set? Are we walking around looking at the horizon
or looking down at a map? Either way, sanity is only a rotate away.

YON, [email protected], Jan C. Hardenbergh, Oki Advanced Products 508-460-8655
http://www.oki.com/people/jch/ =|= 100 Nickerson Rd. Marlborough, MA 01776
Imagination is more important than knowledge - Albert Einstein (1879-1955)