Mathematical XYZ ? 2004-02-26 - By Kris Krieger
Back
At 01:11 AM 26-02-04, RorrKonn wrote:
>In the Math world they have Rules for every thing.
>The rules change depending what Mode ya in but there Rules none the same.
>
>So there has to be a Mathematical XYZ Rule of where
>xyz ? is up and Down.
>xyz ? is left to right.
>xyz ? is front back.
Z is Up/Down. In 2D geometry, X is to the right/left, Y is vertical, but
in 3D, X and Y are perpindicular to each other and they both are
perpendicular to Z. I don't know of any definition that correlates
"Front/Back" or "Left/Right", but that doesn't mean one doesn't exist. If
I was describing sometyhing to someone, I'd define X to be "Left/Right",
but that's jsut a leftover from 2D geometry and I have no idea whether it's
a definition or even accepted convention, rathr than just my own
habit. IOW, I always thought that 2D geometry is basically "looking down
the Z axis" at the plane bisected by X and Y, ergo, when I think of 3D, I
perceive of myself as simply changing position along the imaginary plane
created by Z and Y, which is why I think of X as being left/right (or side
to side).
HTH
>
>What Mode is 3D ?
>Anyone know why every 3D App uses a deferent XYZ's ?
I haven't worked with that many, but my guess would be that either it's a
matter of viewpoint (since X and Y are not necessarily designated as Front
or Side). XFrog seems to present the thing as I described above. I've
tried a little bit of Carrera and LW5, and either a littler bit of Rhino
(which I couldn't make head nor tail of), but all I noted was that the
first two have Z as vertical and I can't remember whetehr they had X as
"side to side" or not.
Come to think of it, I have to check tS but I'm trying to render a scene
right now - doesn't tS set X as being "front/back"...? It might because I
keep getting screwed up with the axes of objects.
As for the reason, my guess (just a guess) is that 3D apps are not designed
or written by mathemeticians. The people who write them seem to all agree
that Z is "Up/Down", from what (admittedly little) I've seen, but the X and
Y thing seems to be a point of disagreement.
HTH
- Kris
- Kris M. Krieger
http://www.pterochromics.com
|
|
