What happened was the Superintendent of C&GS and Weights and Measures adopted the meter in the 1890s as the basic unit of measure then declared 1 foot equals 1200/3937 meters or 39.37 inches equals 1 meter. Tables were published to 4 places so rounded 1 chain equals 20.1168 meters which happens to be the same for international feet (but not rounded).
The problem arose in the early twentieth century when NIST or their predecessor at the request of other professions or industries changed the definition of the foot so that there would be no rounding in the conversion (1 foot equals 0.3048 meters exactly) and we've been dealing with it ever since. It didn't happen instantly, it wasn't until 1959 that it was changed everywhere then they kept the old definition too.
About 20 years ago, Arizona decided they were going metric with their highway design. I don't know how many projects that they did in metric, but they did one here on State Highway 90, approximately 20 miles worth of new construction. That was the end of their going metric regarding highway design work and went back to the way it should be.
This country has almost 500 years of records based on the foot/pound and chain/link measurement system and has worked just fine. Why toss a monkey wrench into mix and make things confusing?
Another thing that shouldn't be done is to survey properties down onto a grid. People are buying what they see up here in the real world, not down on something they can't see or comprehend.
I never could figure out how grid bearings can be brought up on the surface when bring in ground distances. I shake my head on this. Things just don't work that way.
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Which is what I said: "Surveyors working with coordinate systems where the point of origin is a million feet from the situs must pay attention, but can easily rescale their project coordinates."
I assume you're talking about Canada. Actually is was a difficult transition. "The process was fraught with political interference and public resistance, and took place incrementally between 1970 and the early 1980s. Despite the shift, many Canadians still express certain measurements in imperial units, such as height (feet and inches)."
For a good read on how it came down, refer to this:
Be assured and thankful that you missed it.
Blunders can be checked without dual systems of measurement.
Basically, it led to more numbers being transposed in the field and on the keyboard by the new guy.
It was enough for me to find a place that believed in real modernization, digital instruments and data collectors and cadd.
When there is the day that one World wide system is developed and put into place and chiseled into stone for everyone, I will go with the flow.
Meanwhile in reality, there are dozens of systems in place for most every state, country and continent that most people are having some reasons to doubt the results.
In the 60s was happy with varas and the occasional poles (and the many variants that equal 16.5ft) and then, omg now I gotta use feet.............and now which feet...........and metrics for everything, nope.
Any of my 40+yrs of records and GPS control points would have to be converted just to walk out the door.
0.02
There are 57 US jurisdictions out there. Not all deal with units in the SPC section of code. The NGS is going to get push back on this one from somebody. They should stick with meters and let the states screw things up however we want.
Well said
Excellent read, it reads like I would expect it to.
I agree with you for sure Shawn. Chaos is going to ensue, for conversions of SPCS2022 datum SPC coordinates expressed in either foot unit when exporting to (or importing from) other data sets with unknown metadata or without the ability to handle a SPCS2022 coordinate expressed in U.S. Survey feet. The surest way to exchange data may become geographic coordinates to assure that there isn't a mis-match in SPCS units.
For example of possible scenarios, lets say that you have data collected and mapped in SPCS2022 and want to associate it to an orthophoto with unknown SPCS unit of feet either in SPCS2022 or even NAD83 SPCS. The 2ppm difference may be not be able to be ascertained depending on the resolution of the ortho. Without knowledge of what the orthophoto used for SPCS feet units, how could you be sure the data is properly matched?
As you said, there is going to have to be some "heavy lifting" by the software providers, careful analysis and oversight by the surveyor, and a hope for decent documentation and metadata to leave a computational footsteps of the process used for data to be exchanged or correlated. I predict a likelihood chaos for those documents prepared by no-thought button pushers. When data gets mis-mashed merged without a metadata trail of where it came from, it could render usefulness of the combined data to much lower accuracy than potentially it has if the coordination had been done properly. Are we going to look back and say: did we do this to ourselves? Danger Will Robinson.
Watch the webinar.?ÿ Going to all International Feet will not be painful.?ÿ The states have to update their laws anyway, since all those that refer to US Survey Feet also refer to the outgoing NAD83. Survey Foot vs International foot really only matters when converting meter coordinates to feet, or importing state plane coordinates (with large false eastings, for instance) into CAD. Distance-wise the difference is 2ppm, which means that the difference is withing the measuring error of your instruments. You will never notice the difference when putting plans or legal descriptions on the ground (and if you do, just make the conversion like with rods or chains or whatever).
Straight meters everywhere would be best for our industry, but there would be a lot of friction in that change.?ÿ
Have you watched the webinar?
A conversion from feet in NAD83 WA South Zone into Feet SPCS2022 through NGS provided products would be US Survey Feet in (since it is WA S), but 2022 would always be in international feet. Since the conversion has to occur anyway, I don't see how there is any confusion.
You have to convert from NAD83 to 2022 anyway.
In your example, the unit of the feet is unknown anyway, presumably it is unknown today as well. The thing is if you have SPC it is only useful if you know the zone, which if you know that then you know the type of feet. All NGS is really proposing is that the states define the next rendition of their SPCS in International feet. The webinar in no way implied that the international foot should be retroactively applied.
The real method is dividing varas by 0.39 to get feet.
Not to pick nits, but I usually divide varas by 0.36 to get feet.
I stand corrected, my mind saw that and my fat fingers got the best of me....................
The desk I sit at is 5 minutes walk from the Oregon/Washington State line. Washington uses the US Foot, Oregon the Int'l Foot. So I'm switching back and forth every day. Sometimes more than once. But it's just one more thing on the checklist. Not a big crisis. More like an annoyance.
Still, I'd like to see the next one to be all one, or all the other. No state is going metric. Not now. The NGS is not going for US Foot. So I'd like to see the Int'l foot used across the board. All you dinosaurs will get over it in about 3 weeks.
Why on earth should NGS be talking in terms of feet in the first place? Can't they make up their minds? They made the decision, years ago, I might add, that all positions and results would be reported in meters with the individual states mandating what ever foot they wished.?ÿ NGS is a Geodesy organization and they need to stay within their lane, and let the rest of the world make their own decision as to the final form. they use on a day to day basis.
the millimeter is smaller than practical for most general Surveying tasks, the centimeter is larger than is desirable.?ÿ
The foot is larger than is desirable, too.?ÿ That's why surveyors using feet have decimal places in their numbers.?ÿ In metric, use however many places you think appropriate.?ÿ I think in millimeters and/or centimeters routinely when comparing things, but surveying measurements would be expressed as meters and decimals.
Michael Dennis is assuming that "feet" in one or both versions will creep back into NGS products. Wouldn't it be handy for NCAT to publish (your version of) feet as well as meters? And on the survey mark datasheets? etc.
Michael mentioned this topic to me in an email before the webinar (I'd queried about the 0-360 longitudes) to which I'd responded negatively which surprised him. Esri already more-or-less supports both foot versions and will have to continue to support both for years no matter what happens in 2022. I was negative because I thought there would be lots of push-back and I'm cynical that way.
I heard the same from Michael. I can't fault his argument. As you say, from a software perspective, we'll have to support both indefinitely. I'm wondering in our products if we'll need to limit the units selection when 2022 is selected to meters and international feet only.
I don't think there is a perfect answer. All of them have some sort of liabilities.
I lean toward going only to meters and let users pick their units and make the conversions, but that is problematic as well.
As far as staying "within their lane" goes, the US Constitution leaves establishing weights and measures to the Federal government, not the State government. I agree with everything else you said, but ultimately the Federal government has the authority in this (and should).
Doesn't the longitude format used in climate model data have something to do with the change to 0 - 360?