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Marginally related: In 2020, the United States finally decided to adopt the International Foot (1959, 304.8 mm, based on the 914.4 mm yard / 25.4 mm inch) for l

Marginally related: In 2020, the United States finally decided to adopt the International Foot (1959, 304.8 mm, based on the 914.4 mm yard / 25.4 mm inch) for land surveying, which is already the standard that's followed in all engineering disciplines apart from surveying. Now the historical US Survey Foot (1893) will soon been abolished for good. It's an interesting piece of news, but due to its horrible title, it'll probably never be voted to the homepage (a better title to me would be "The United States finally adopts International Foot, abolishes survey foot"). * America Has Two Feet. It’s About to Lose One of Them https://news.ycombinator.com/item?id=24196228 https://news.ycombinator.com/item?id=24196228

ahupp 6y ago
Does that mean measurements need to specify which kind of foot they are using, in case they might predate the switchover?
- taejo 6y ago
  It's not so much a switchover as the end of a switchover. The international foot was adopted in 1959, and everything since (at least in surveying) should specify (but often does not, which is one of the reasons the survey foot needs to be abolished)
1-6 6y ago
The US Survey foot is defined as 1200/3937 and the international survey foot is exactly 0.3048 meters. When taking data into applications such as Autodesk Civil 3D, you need to transpose Lat/Long GIS data into a flat Cartesian coordinate system. For example, X,Y values in California start in X=6,000,000 Y=2,000,000 which starts eating up floating point precision. Because 1200/3937 doesn't divide cleanly, you'll end up with varying values depending on where you cut off your precision. That's why Highly Composite Numbers are critical.
- GoOnThenDoTell 6y ago
  Use fixed point?
  - taneq 6y ago
    You'll need rational numbers, not just fixed point, since it's a recurring decimal. (Unless it's a non-recurring decimal in base 2, I guess, but even then, the moment you do something with it you'll probably need a rational representation.)
- jeffbee 6y ago
  You lost me there with the 6 million X coordinates in California. 6 million whats starting from where? It can't be feet from the prime meridian, that's not far enough. I've been scraping my county assessor's GIS database for property outlines and I noticed that the coordinates are huge, as you mentioned. I assumed it was just some fanciful origin but I'd love to know the story.
  - maxerickson 6y ago
    Probably a https://en.wikipedia.org/wiki/State_Plane_Coordinate_System https://en.wikipedia.org/wiki/State_Plane_Coordinate_System zone. Typically designed to have similar error across the whole area and things like that.
  - chronomex 6y ago
    Yeah, it's feet measured east and north of an arbitrary point southwest of everything in the state. There is an actual point inside the state used as a base but they set up a false easting and false northing by subtracting a large round number such that the origin of the coordinate system is southwest of everything in the state. A lot of things in surveying are designed such that the math is easier for people working in the field to reliably get correct.
- msla 6y ago
  > For example, X,Y values in California start in X=6,000,000 Y=2,000,000 which starts eating up floating point precision. Why isn't the origin at (0, 0)? It's like saying your ground is at 1,532 volts: You're defining the coordinate system, why make work for yourself?
  - abduhl 6y ago
    One reason for the large numbers is that so when data is imported into a drawing it is immediately obvious whether it shares the same coordinate system. If multiple sets of points from different disciplines are imported into the program then the draftsman knows whether the coordinate systems are the same by visual inspection (to a rough degree). Also because nobody wants to use negative numbers or have the possibility of a negative number showing up.
    - pavlov 6y ago
      > “... nobody wants to use negative numbers” It’s hard to understand these priorities. An unholy mix of base-12 and base-16 is fine, but negative numbers are too difficult to work with?
      - abduhl 6y ago
        When you’re working with a couple guys who probably went on a bender last night out in the middle of nowhere with no cell service and a piece of shit walkie talkie that has spotty transmission you sometimes end up having to throw up hand signs to signal northing and easting values. There’s no hand signal for negative. So yeah, negative numbers are hard to work with in that case.
- lmm 6y ago
  No number has all factors in. Better to work in a way that handles uneven fraction properly than sweep the problem under the rug.
  - corty 6y ago
    Well, you could just use the first few primes multiplied together as a base. 2 * 3 gives you base6, 2 * 3 * 5 gives you base30. Neither commonly used system does that, base12 uses 2 twice, base10 skips 3. So from a divisibility PoV both are lacking. But arithmetics is base10 anyways, since thats close to the average number of fingers for humans, so...
- deleted 6y ago
  [deleted]
taneq 6y ago
Uh, you mean 25.4mm as the standard inch? Or that times 12 as the standard foot?
- segfaultbuserr 6y ago
  It was a typo, now corrected.
coderintherye 6y ago
>it'll probably never be voted to the homepage Incorrect, it was in fact voted to the homepage 7 months ago: https://news.ycombinator.com/item?id=22203919 https://news.ycombinator.com/item?id=22203919
- deleted 6y ago
  [deleted]
- karmakaze 6y ago
  Or 13 days ago. I know I read it recently--though perhaps on page 2.. https://news.ycombinator.com/item?id=24196228 https://news.ycombinator.com/item?id=24196228
riffraff 6y ago
the fact that the US decided to adopt an "International Foot" which is used primarily only in the US is quite funny :) .
- qw 6y ago
  It's similar to how some teams that win the national championship in NFL are called "World Champions"... a sport that is played professionally in only one country.
- rob74 6y ago
  Back in 1959, when it was adopted, it was still used in a few more countries... and, with Brexit, who knows?
  - squiggleblaz 6y ago
    You seriously think the UK will revert to the imperial system? I know they still make some use of imperial measures, but you're implying more than just some legacy imperial, but rather a reversion.
- squiggleblaz 6y ago
  To be fair, when it was invented, it was still in widespread use through the dying British empire.

ahupp 6y ago

Does that mean measurements need to specify which kind of foot they are using, in case they might predate the switchover?

taejo 6y ago
It's not so much a switchover as the end of a switchover. The international foot was adopted in 1959, and everything since (at least in surveying) should specify (but often does not, which is one of the reasons the survey foot needs to be abolished)

1-6 6y ago

The US Survey foot is defined as 1200/3937 and the international survey foot is exactly 0.3048 meters. When taking data into applications such as Autodesk Civil 3D, you need to transpose Lat/Long GIS data into a flat Cartesian coordinate system. For example, X,Y values in California start in X=6,000,000 Y=2,000,000 which starts eating up floating point precision. Because 1200/3937 doesn't divide cleanly, you'll end up with varying values depending on where you cut off your precision. That's why Highly Composite Numbers are critical.

GoOnThenDoTell 6y ago
Use fixed point?
- taneq 6y ago
  You'll need rational numbers, not just fixed point, since it's a recurring decimal. (Unless it's a non-recurring decimal in base 2, I guess, but even then, the moment you do something with it you'll probably need a rational representation.)
jeffbee 6y ago
You lost me there with the 6 million X coordinates in California. 6 million whats starting from where? It can't be feet from the prime meridian, that's not far enough. I've been scraping my county assessor's GIS database for property outlines and I noticed that the coordinates are huge, as you mentioned. I assumed it was just some fanciful origin but I'd love to know the story.
- maxerickson 6y ago
  Probably a https://en.wikipedia.org/wiki/State_Plane_Coordinate_System https://en.wikipedia.org/wiki/State_Plane_Coordinate_System zone. Typically designed to have similar error across the whole area and things like that.
- chronomex 6y ago
  Yeah, it's feet measured east and north of an arbitrary point southwest of everything in the state. There is an actual point inside the state used as a base but they set up a false easting and false northing by subtracting a large round number such that the origin of the coordinate system is southwest of everything in the state. A lot of things in surveying are designed such that the math is easier for people working in the field to reliably get correct.
msla 6y ago
> For example, X,Y values in California start in X=6,000,000 Y=2,000,000 which starts eating up floating point precision. Why isn't the origin at (0, 0)? It's like saying your ground is at 1,532 volts: You're defining the coordinate system, why make work for yourself?
- abduhl 6y ago
  One reason for the large numbers is that so when data is imported into a drawing it is immediately obvious whether it shares the same coordinate system. If multiple sets of points from different disciplines are imported into the program then the draftsman knows whether the coordinate systems are the same by visual inspection (to a rough degree). Also because nobody wants to use negative numbers or have the possibility of a negative number showing up.
  - pavlov 6y ago
    > “... nobody wants to use negative numbers” It’s hard to understand these priorities. An unholy mix of base-12 and base-16 is fine, but negative numbers are too difficult to work with?
    - abduhl 6y ago
      When you’re working with a couple guys who probably went on a bender last night out in the middle of nowhere with no cell service and a piece of shit walkie talkie that has spotty transmission you sometimes end up having to throw up hand signs to signal northing and easting values. There’s no hand signal for negative. So yeah, negative numbers are hard to work with in that case.
lmm 6y ago
No number has all factors in. Better to work in a way that handles uneven fraction properly than sweep the problem under the rug.
- corty 6y ago
  Well, you could just use the first few primes multiplied together as a base. 2 * 3 gives you base6, 2 * 3 * 5 gives you base30. Neither commonly used system does that, base12 uses 2 twice, base10 skips 3. So from a divisibility PoV both are lacking. But arithmetics is base10 anyways, since thats close to the average number of fingers for humans, so...
deleted 6y ago
[deleted]

taneq 6y ago

Uh, you mean 25.4mm as the standard inch? Or that times 12 as the standard foot?

segfaultbuserr 6y ago
It was a typo, now corrected.

coderintherye 6y ago

>it'll probably never be voted to the homepage Incorrect, it was in fact voted to the homepage 7 months ago: https://news.ycombinator.com/item?id=22203919 https://news.ycombinator.com/item?id=22203919

deleted 6y ago
[deleted]
karmakaze 6y ago
Or 13 days ago. I know I read it recently--though perhaps on page 2.. https://news.ycombinator.com/item?id=24196228 https://news.ycombinator.com/item?id=24196228

riffraff 6y ago

the fact that the US decided to adopt an "International Foot" which is used primarily only in the US is quite funny :) .

qw 6y ago
It's similar to how some teams that win the national championship in NFL are called "World Champions"... a sport that is played professionally in only one country.
rob74 6y ago
Back in 1959, when it was adopted, it was still used in a few more countries... and, with Brexit, who knows?
- squiggleblaz 6y ago
  You seriously think the UK will revert to the imperial system? I know they still make some use of imperial measures, but you're implying more than just some legacy imperial, but rather a reversion.
squiggleblaz 6y ago
To be fair, when it was invented, it was still in widespread use through the dying British empire.