• Ashelyn@lemmy.blahaj.zone
    link
    fedilink
    arrow-up
    103
    arrow-down
    1
    ·
    2 months ago

    The scaled down rectangle should be narrower; it’s not scaled in this diagram, it’s squished.

    (Yes I know you can ‘scale’ objects on one axis but that’s usually not how it’s taught on an introductory level. Standard scaling assumes object similarity, which is not present in the diagram’s ‘scaled’ rectangle.)

    • woodgen@lemm.ee
      link
      fedilink
      arrow-up
      11
      arrow-down
      1
      ·
      edit-2
      2 months ago

      Scaling in 2D has 2 parameters, X and Y, in the example X was at 1 while Y was below 1. You are referring to a subset of scaling transformation where X = Y and the aspect ratio is kept.

      • Ashelyn@lemmy.blahaj.zone
        link
        fedilink
        arrow-up
        13
        arrow-down
        1
        ·
        2 months ago

        Yes, and introductory geometry courses teach students how to do uniform scaling far before they teach them axis-based because it’s better illustrative of the concepts of similarity and congruence

      • shundi82@sh.itjust.works
        link
        fedilink
        arrow-up
        5
        arrow-down
        1
        ·
        edit-2
        2 months ago

        And what about the arrow?

        It’s pointing down diagonally, which - at least to me (and for pretty much any GUI I can think of) - indicates, that it should be affecting both axes.

        Then again, that whole illustration isn’t all that great to begin with. So who knows, what that arrow is supposed to signify…

      • Ashelyn@lemmy.blahaj.zone
        link
        fedilink
        arrow-up
        1
        ·
        edit-2
        2 months ago

        Cool, now explain that to a class of 7th graders for me

        edit: raised grade, it may been set a low but it varies. I think most kids start to learn this stuff in/around middle school

        edit 2: also mirrored objects are generally considered similar so that’s fine

    • chad@sh.itjust.works
      link
      fedilink
      arrow-up
      4
      ·
      edit-2
      2 months ago

      Ackchuawually, this example depicts a squish and a translation. A true scaling would have the scaling being done in place, resulting in an overlayed and smaller rectangle.