6 ms·

Things I think should be disallowed: - traffic messages that are displayed by rotating through three or more screens; two is fine if necessary, as you can inge

by cvoss 3y ago

Things I think should be disallowed: - traffic messages that are displayed by rotating through three or more screens; two is fine if necessary, as you can ingest all of it in short order; but to keep staring at it waiting for the third screen is just way too dangerous - digital advertising billboards, for the same reason; these are even worse because the ads are generally poorly designed with tiny fonts that are hard to read at a glance I have a strong preference for an analog speedometer for the same reasons. In an instant your eyes can discern whether you are accelerating or decelerating. On a digital display, with a measly 1 MPH resolution, you have to keep looking down over and over to determine if you are maintaining your speed.

jaywalk 3y ago
The digital speedometer on my vehicle is surrounded by an "analog" speedometer. I'm not sure why anyone would need it to determine whether they are accelerating or decelerating, but it's there.
- cvoss 3y ago
  If you want to maintain a particular speed, you need to know not only your current speed but also your acceleration. Otherwise you are frequently going to be slipping pretty far off your target before you notice. High latency control loops like that are an impediment to precision. If you are accelerating at 1 mph per second, it can take up to an entire second for the digital display to indicate that you are accelerating at all, and, even then, you still don't know how fast you are accelerating. The resolution just isn't good enough.
  - jjk166 3y ago
    Humans can detect accelerations as low as .25 mph/s so while you might not know exactly what your acceleration rate is, you definitely would be aware that you are accelerating and whether your efforts to compensate are increasing or decreasing it. And these very low acceleration rates take a very long time to significantly alter your speed. On an analogue dial you probably wouldn't even notice the movement. In practice, maintaining speed in a vehicle is pretty darn simple.
    - lmm 3y ago
      > Humans can detect accelerations as low as .25 mph/s Maybe under ideal conditions. Not while driving. And below .25 is still enough to have you drift off speed. > you definitely would be aware that you are accelerating and whether your efforts to compensate are increasing or decreasing it. It is by no means definite. It's very easy to drift off the correct speed when e.g. the slope of the road changes, even if you're trying not to.
      - jjk166 3y ago
        With what level of precision are you trying to maintain constant speed? At .25 mph/s it takes 4 seconds to have a 1 mph change in speed. At highway speeds the change in your position from where you'd expect to be at perfectly constant velocity would be 0.8%, or about 3 feet off. That's nothing compared to the variability of your speedometer, which is only accurate to about +/- 10%. If you're a blue angel trying to fly in close formation at hundreds of miles per hour, yeah that's not good enough, but for a normal person driving on a road it is trivially simple to keep your speed within the margin of error of your speedometer.
    - Turskarama 3y ago
      You might be able to detect an acceleration, but I bet you can't accurate gauge how fast that acceleration is.
      - jjk166 3y ago
        But why do you need to gauge rate of acceleration? If you're trying to maintain constant speed, you want an absence of acceleration.
- jdietrich 3y ago
  It's easier to eyeball an angle at a glance than to read a number. Some digital speedos subtly change color as you approach and exceed the speed limit, which is a particularly elegant affordance.
jiehong 3y ago
That reminds me of the Citroën CX speedometer that was like a horizontal ribbon (probably a cylinder though): http://i.ytimg.com/vi/BQSdmmRemeg/maxresdefault.jpg http://i.ytimg.com/vi/BQSdmmRemeg/maxresdefault.jpg
- jaclaz 3y ago
  Yep, it was a cylinder, here is a naked picture: https://www.varaosahaku.fi/image/900/a/85/d62c83/path/mnt/newftp/840/fibdb/bild/lgnr/9379(1).jpg https://www.varaosahaku.fi/image/900/a/85/d62c83/path/mnt/ne...
Zak 3y ago
Aircraft with digital displays usually use a scrolling column of numbers analogous to a tape measure for critical information like airspeed and altitude. This provides information at a glance with digital precision and a more compact display because the full range doesn't need to be shown all the time.
- cpgxiii 3y ago
  Notably, some pre-glass cockpit military aircraft had (and some still have, e.g. B-1B) analog "tape" displays for these values as well. Only in the civilian sector were round dial gauges the standard right up to glass cockpits.

by cvoss 3y ago

jaywalk 3y ago

The digital speedometer on my vehicle is surrounded by an "analog" speedometer. I'm not sure why anyone would need it to determine whether they are accelerating or decelerating, but it's there.

cvoss 3y ago
If you want to maintain a particular speed, you need to know not only your current speed but also your acceleration. Otherwise you are frequently going to be slipping pretty far off your target before you notice. High latency control loops like that are an impediment to precision. If you are accelerating at 1 mph per second, it can take up to an entire second for the digital display to indicate that you are accelerating at all, and, even then, you still don't know how fast you are accelerating. The resolution just isn't good enough.
- jjk166 3y ago
  Humans can detect accelerations as low as .25 mph/s so while you might not know exactly what your acceleration rate is, you definitely would be aware that you are accelerating and whether your efforts to compensate are increasing or decreasing it. And these very low acceleration rates take a very long time to significantly alter your speed. On an analogue dial you probably wouldn't even notice the movement. In practice, maintaining speed in a vehicle is pretty darn simple.
  - lmm 3y ago
    > Humans can detect accelerations as low as .25 mph/s Maybe under ideal conditions. Not while driving. And below .25 is still enough to have you drift off speed. > you definitely would be aware that you are accelerating and whether your efforts to compensate are increasing or decreasing it. It is by no means definite. It's very easy to drift off the correct speed when e.g. the slope of the road changes, even if you're trying not to.
    - jjk166 3y ago
      With what level of precision are you trying to maintain constant speed? At .25 mph/s it takes 4 seconds to have a 1 mph change in speed. At highway speeds the change in your position from where you'd expect to be at perfectly constant velocity would be 0.8%, or about 3 feet off. That's nothing compared to the variability of your speedometer, which is only accurate to about +/- 10%. If you're a blue angel trying to fly in close formation at hundreds of miles per hour, yeah that's not good enough, but for a normal person driving on a road it is trivially simple to keep your speed within the margin of error of your speedometer.
  - Turskarama 3y ago
    You might be able to detect an acceleration, but I bet you can't accurate gauge how fast that acceleration is.
    - jjk166 3y ago
      But why do you need to gauge rate of acceleration? If you're trying to maintain constant speed, you want an absence of acceleration.
jdietrich 3y ago
It's easier to eyeball an angle at a glance than to read a number. Some digital speedos subtly change color as you approach and exceed the speed limit, which is a particularly elegant affordance.

jiehong 3y ago

That reminds me of the Citroën CX speedometer that was like a horizontal ribbon (probably a cylinder though): http://i.ytimg.com/vi/BQSdmmRemeg/maxresdefault.jpg http://i.ytimg.com/vi/BQSdmmRemeg/maxresdefault.jpg

jaclaz 3y ago
Yep, it was a cylinder, here is a naked picture: https://www.varaosahaku.fi/image/900/a/85/d62c83/path/mnt/newftp/840/fibdb/bild/lgnr/9379(1).jpg https://www.varaosahaku.fi/image/900/a/85/d62c83/path/mnt/ne...

Zak 3y ago

Aircraft with digital displays usually use a scrolling column of numbers analogous to a tape measure for critical information like airspeed and altitude. This provides information at a glance with digital precision and a more compact display because the full range doesn't need to be shown all the time.

cpgxiii 3y ago
Notably, some pre-glass cockpit military aircraft had (and some still have, e.g. B-1B) analog "tape" displays for these values as well. Only in the civilian sector were round dial gauges the standard right up to glass cockpits.