• yopyop@feddit.de
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    1 year ago

    I work in 3D metrology and the consensus is right handed and Z up. Had no idea left handed existed!

    • heeplr@feddit.de
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      1 year ago

      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
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        1 year ago

        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
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          1 year ago

          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
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        1 year ago

        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
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          1 year ago

          Sorry for being unclear, I was talking about screen projection. For actual rasterization.

  • JATtho@sopuli.xyz
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    1 year ago

    It gets more cursed the more you look at it:

    • you have to convert the coordinate axes (swap z,x,y)
    • then you find out the right/left handed is flipped
    • now your brain melts if you even try think how to solve this with transformation/rotation, what ever.
  • Buck Fucket@lemmy.world
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    1 year ago

    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
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      1 year ago

      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
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        1 year ago

        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
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        1 year ago

        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
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          1 year ago

          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
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        1 year ago

        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
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          1 year ago

          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.