I thought right-hand rule with Z up as thumb was standard in science? You usually project on the xy-plane, for example when calculating the distance to objects on a flat surface.
I only know thumb = motion/current but now since you say, it's clear: people used x/y for 2D logically but the 2D plane used to be paper. which is parallel to the earth surface (usually). Computer screens are perpendicular so Y points up, not away from you.
So this makes sense with paper, TIL. With computers, Z traditionally means depth.
TBH I'm not sure I totally understand the question but projection is very useful to decompose the orientation of elements, like a cylinder that you just measured with a machine or a scanner. The coordinates and orientation (angles) can be projected in the three main planes XY, YZ and ZX.
Ugh, when I have to open CAD for a project at work I have to setup a new coordinate system with Z going up, every time. The engineers just work with Y up for some reason. Too lazy to change it perhaps? Solid works and Inventor default Y up? I'll never understand it. I definitely understand this meme. There's also models with an origin 10 feet off in X and 20 feet out in Y. I just do not friggin get it man.
That's not true though. While there isn't a standard, convention is to have z up in mathematics, as z is extending the xy plane we normally work with into a third space.
On paper, when I was learning Descartes' coordibate system, we used Y as up and X as left-right. And when it was time to plot in 3D, we used Z to "extend" the plane into yourself and away from yourself.
You just hold your sheet of paper perpendicular to the ground (or just use a whiteboard) and it all makes sense.
What I can't get is imperial measurement system. Apparently, nobody but americans can
I'm not American but I've been living in the USA for ten years and I still have trouble with imperial measurements. It's painful dealing with fractions of an inch instead of millimeters.
CAD used to be digital abstraction of the physical media that is 2D drawings on paper, so XY is the plane of the paper going horizontal/vertical, and most detailing are in vertical cross sections so Y ended up being up most of the time.
The Z axis is then Frankensteined into the existing system to get a proper 3D representation, so it became the depth axis for the existing XY plane.
In Minecraft it's even more evident as Notch Frankensteined the Z axis into a game engine that's originally developed for side scrolling.
In robotics I use right hand coordinates with z up. So a car is moving in the 2d xy plane and z is the optional third component. This makes sense to me. For some kind of painting on the screen I can understand why you use y as up. Then again, I know these as uv-coordinates.
44 Comments
croobat@lemmy.world · 83 pts · 3y
I found this handy reference a while ago. But yeah, we are kinda screwed.
jukibom@lemmy.world · 26 pts · 3y
TheGreenGolem@lemm.ee · 9 pts · 3y
YET
spartanatreyu@programming.dev · 7 pts · 3y
Good news, X is now down.
shotgun_crab@lemmy.world · 20 pts · 3y
At least they haven't invented X up (yet)
hairinmybellybutt@lemmy.world · 23 pts · 3y
You'll never believe my startup idea
Hexarei@programming.dev · 4 pts · 3y
Dude you totally stole that idea from me, now you owe me half
TheUnicornOfPerfidy@lemmy.ml · 3 pts · 3y
There's only one quadrant of this that should be acceptable to anyone! Positive X, positive Y!
Vorthas@lemmy.ml · 6 pts · 3y
Nope, the bottom right quadrant is the acceptable one. Z is up and follows the right-hand rule. I will die on this hill.
heeplr@feddit.de · 5 pts · 3y
you'll get bitten during projection when depth is converted to 2D screen coordinates, which is X and Y. Better do it right from the start.
Widowmaker_Best_Girl@lemmy.world · 2 pts · 3y
Minecraft ruined me as a kid. I'm still mad that so many softwares use Z as up. I'm still not happy about it.
Y up feels much more comfortable for me.
Cavemanfreak@vlemmy.net · 5 pts · 3y
Y up is also the standard in 2D graphs, so it makes sense that Z is depth.
TheUnicornOfPerfidy@lemmy.ml · 1 pts · 3y
I don't think anyone got my joke 🤷
croobat@lemmy.world · 1 pts · 3y
Let's die together chief
yopyop@feddit.de · 16 pts · 3y
I work in 3D metrology and the consensus is right handed and Z up. Had no idea left handed existed!
heeplr@feddit.de · 4 pts · 3y
How does projection work in your field? X, Y, Z get converted to X, Z and 2D screen planars have no Y axis?
Who invented this, why did she do it and where to send my official letter of complaint?
Pelicanen@sopuli.xyz · 5 pts · 3y
I thought right-hand rule with Z up as thumb was standard in science? You usually project on the xy-plane, for example when calculating the distance to objects on a flat surface.
heeplr@feddit.de · 2 pts · 3y
I only know thumb = motion/current but now since you say, it's clear: people used x/y for 2D logically but the 2D plane used to be paper. which is parallel to the earth surface (usually). Computer screens are perpendicular so Y points up, not away from you.
So this makes sense with paper, TIL. With computers, Z traditionally means depth.
yopyop@feddit.de · 1 pts · 3y
TBH I'm not sure I totally understand the question but projection is very useful to decompose the orientation of elements, like a cylinder that you just measured with a machine or a scanner. The coordinates and orientation (angles) can be projected in the three main planes XY, YZ and ZX.
heeplr@feddit.de · 2 pts · 3y
Sorry for being unclear, I was talking about screen projection. For actual visualization.
kogasa@programming.dev · 3 pts · 3y
This can happen if you accidentally pilot your player character into a singular linear transformation.
RedditRefugeeTom@lemmy.world · 9 pts · 3y
Ugh, when I have to open CAD for a project at work I have to setup a new coordinate system with Z going up, every time. The engineers just work with Y up for some reason. Too lazy to change it perhaps? Solid works and Inventor default Y up? I'll never understand it. I definitely understand this meme. There's also models with an origin 10 feet off in X and 20 feet out in Y. I just do not friggin get it man.
TwilightKiddy@programming.dev · 15 pts · 3y
Because math works with Y up. Physics steal from math, engeneering steals from physics, so, here you are.
What I can't get is imperial measurement system. Apparently, nobody but americans can. And that stuff is far worse than Y and Z switching places.
ionburger@lemmy.sdf.org · 7 pts · 3y
as a minecraft player learning how to use autocad, i thought y up was alot more ubiquitous then it apparently is
Widowmaker_Best_Girl@lemmy.world · 3 pts · 3y
That's what I don't get. Why would they make Z up when in algebra, Y is up. It's all based on math, shouldn't we keep consistent on that?
Mhlindsey@lemmy.fmhy.ml · 2 pts · 3y
Because the z axis is represented as an extension of the xy-plane, coming out of the paper essentially, so we represent it as up
Mhlindsey@lemmy.fmhy.ml · 1 pts · 3y
That's not true though. While there isn't a standard, convention is to have z up in mathematics, as z is extending the xy plane we normally work with into a third space.
TwilightKiddy@programming.dev · 3 pts · 3y
Might depend on where you were learning.
On paper, when I was learning Descartes' coordibate system, we used Y as up and X as left-right. And when it was time to plot in 3D, we used Z to "extend" the plane into yourself and away from yourself.
You just hold your sheet of paper perpendicular to the ground (or just use a whiteboard) and it all makes sense.
dan@upvote.au · 1 pts · 3y
I'm not American but I've been living in the USA for ten years and I still have trouble with imperial measurements. It's painful dealing with fractions of an inch instead of millimeters.
amanaftermidnight@lemmy.world · 4 pts · 3y
CAD used to be digital abstraction of the physical media that is 2D drawings on paper, so XY is the plane of the paper going horizontal/vertical, and most detailing are in vertical cross sections so Y ended up being up most of the time.
The Z axis is then Frankensteined into the existing system to get a proper 3D representation, so it became the depth axis for the existing XY plane.
In Minecraft it's even more evident as Notch Frankensteined the Z axis into a game engine that's originally developed for side scrolling.
heeplr@feddit.de · 3 pts · 3y
In which world should Z point up and Y represent depth?
Totally crazy opposite world, where cats hunt dogs and rain goes up? This is plain evil...! :-)
MooseBoys@lemmy.world · 8 pts · 3y
Nobody commenting on the chirality difference…
reversed95@programming.dev · 8 pts · 3y
It’s called the theory of Gravity after all
JATtho@sopuli.xyz · 8 pts · 3y
It gets more cursed the more you look at it:
LittleWizard@feddit.de · 5 pts · 3y
In robotics I use right hand coordinates with z up. So a car is moving in the 2d xy plane and z is the optional third component. This makes sense to me. For some kind of painting on the screen I can understand why you use y as up. Then again, I know these as uv-coordinates.
Eh_I@lemmy.world · 5 pts · 3y
Fuck it, the world is sideways now.
Fafner@yiffit.net · 5 pts · 3y
Because no one can agree what way up is!!
deaf_fish@lemm.ee · 4 pts · 3y
I feel like the cat's coordinate system needs to be rotated 90° to the right.
axexrx@reddthat.com · 1 pts · 3y
Otherwise its still hovering
TurretCorruption@lemmy.world · 3 pts · 3y
And this is why you always export for the software you intend to use it in.
Tabboo@lemmy.world · 2 pts · 3y
UCS rotate
amanaftermidnight@lemmy.world · 1 pts · 3y
I feel this meme in all of my rigged bones
interdimensionalmeme@lemmy.ml · 1 pts · 3y
Just label them up, north, east instead of x,y,z