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

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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?

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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.

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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.

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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.

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

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I found this handy reference a while ago. But yeah, we are kinda screwed.

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There’s only one quadrant of this that should be acceptable to anyone! Positive X, positive Y!

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Nope, the bottom right quadrant is the acceptable one. Z is up and follows the right-hand rule. I will die on this hill.

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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.

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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.

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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…! :-)

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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.

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