I was putting up some wall decorations earlier today and was painstakingly realigning everything until it looked level to my eyes. It might be just a hair off, but if I don’t correct it, I’ll see the misalignment almost instantly and get bothered for the rest of time until I fix it. Has anyone investigated, or is there literature on the minimum perceptible angle from level to the naked eye?

  • @[email protected]
    link
    fedilink
    217 days ago

    I believe it depends on the environment.
    Meaning crooked walls/ceiling/floor influence what we believe is visually straight.

  • Schwim Dandy
    link
    fedilink
    118 days ago

    I can’t find anything at all regarding discussion, study or opinions on the question but I can tell you that it depends on the person and most likely, they’re experience in working at leveling/setting plumb.

    Having used levels(spirit, laser, etc.) for decades, I can set an object like a stud, header or a picture for my wife and often don’t need to move it after checking with a level but my wife will often notice that a group of items aren’t leveled the same on a wall but she won’t be sure which one is off. There will usually be a few adjustments to all of them before she’s happy.

  • Romkslrqusz
    link
    fedilink
    86 days ago

    I once hung a TV level to Earth’s gravity. And then I found out that the floor and ceiling weren’t level, so the TV looked crooked anyways.

  • @[email protected]
    link
    fedilink
    368 days ago

    That’s actually a pretty good question.

    With no exact answer, I do think this will at least in part depend on relative comparison to how exactly level your floor/ceiling/counter/table or other frame of reference is, which itself might not be perfect.

    Side note, basically every smart phone out there has orientation sensors, so it should be just as easy as downloading a Bubble Level app from the app store.

    • @[email protected]
      link
      fedilink
      36 days ago

      Since the imperfections of your room may make what looks level not perfectly level, I say don’t use a spirit level. You want it to look right.

    • @[email protected]
      link
      fedilink
      27 days ago

      Side note, basically every smart phone out there has orientation sensors, so it should be just as easy as downloading a Bubble Level app from the app store.

      not when almost every phone has a camera bump, volume rockers and a power button.

      i.e. no long flat sides, that still allow you to see the screen.

      • @[email protected]
        link
        fedilink
        27 days ago

        You do have a point, but most phones have one edge that doesn’t have any buttons, and most people have their phone in a case, which assuming it’s a proper fitting case, usually cancels out that camera bump issue and makes it sit properly flat on a table.

        • @[email protected]
          link
          fedilink
          1
          edit-2
          6 days ago

          I haven’t Bhad a case which sisn’t didn’t mirror the camera bump in a long while unfortunately

            • @[email protected]
              link
              fedilink
              1
              edit-2
              6 days ago

              different language auto-correct really didn’t help my inborn lack of spelling, and I (apparently) didn’t even glance back to check what I wrote.

  • Nakoichi [they/them]
    link
    fedilink
    English
    28 days ago

    I believe the vestibular system does this for us. It’s basically a little level in our ears.

  • @[email protected]
    link
    fedilink
    26 days ago

    According to almost every photo I take, about 3 degrees off.

    Pretty sure this is a psychophysics question, though I don’t know that field well enough to know what’s there.

  • @[email protected]
    link
    fedilink
    English
    46 days ago

    I recall a carnival-type installation, were a whole house was built at an angle, and at the end of it they had a water spigot they turned on, and the water flowed “uphill” (to the human eye).

    • @[email protected]
      link
      fedilink
      36 days ago

      I’ve been to one of these! There was a hill within the house that is way steeper than it looks and it was super freaky and disorienting. Just being in that place gave me motion sickness

  • @[email protected]
    link
    fedilink
    37 days ago

    depends HEAVILY on the eye. some folks are really good at eyeballing shit. usually this goes hand in hand with other “visual calculus” skills like telling whether two things are the same size or determining angles at a glance.

    reckon it’s just spatial reasoning + visualization + practice. i had an uncle who could look at a mechanical system and tell you exactly where all the wear would occur. i always thought it was some kind of savant trick until i started working on similar stuff.

    the brain is just another muscle, you can train it to so all sorts of really amazing things!

  • davel [he/him]
    link
    fedilink
    English
    47 days ago

    I think it depends on 1) the person and 2) the context and 3) the desired precision. I would use an actual level to test against my intuition before I’d have confidence in it.

  • @[email protected]
    link
    fedilink
    English
    26 days ago

    I don’t know too much about this area, but I do know that this kind of task involves a bunch of complex processing in the brain. The more “Mechanical” aspects of vision could be described as visual acuity (sharpness of vision). However, gauging whether something is wonky would be a visual discrimination task, which involves more work by the brain. It’s an area in which one’s skill can be improved through learning, and some occupations have a lower discrimination threshold (I e. They can detect smaller differences).

  • @[email protected]
    link
    fedilink
    English
    47 days ago

    It depends on the distance to object. Also the distance between the object and something to compare it to.