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State Plane Coordinates
Posted by loyal on December 21, 2019 at 7:09 pmOkay…I’m sure that I have said this before, but here I go again.
State Plane Coordinates are GREAT (for some things like Corner Records), BUT only when “they” are properly (correctly) computed! Unfortunately, not everyone seems to be able to do that. I’m NOT talking about modifrickingfied SPC here, but good old SIMPLE (real) SPC values (NAD27 or NAD83).
And I’m not just talking about GPS/GNSS derived (BPM) values here. State Plane Coordinates have an undeserved (IMO) reputation in these parts, that originates with SURVEYOR Nitwits that can’t seem to get their pointy little heads around the well documented (since the 1930s) procedure for computing these babies.
Owning a Rifle doesn’t make you a Rifleman,
Owning a guitar doesn’t make you a Musician,
Owning a computer doesn’t make you a Geodesist,
Owning a GPS/GNSS system doesn’t make you a Surveyor!
Rant over, back to my crystal ball/Ouija Board, and several “sets” of SPC values (1974, 1986, 1999) on some PLSS corners now under several hundred feet of water.
🙁
Loyal
Norm replied 4 years, 7 months ago 17 Members · 33 Replies -
33 Replies
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Lightnin’ Hopkins calcs my SPCs…
I computed computed some SPCs this morning…
Ol’ Lightinin’ shore was pleased…
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SPCs determined in 1974 & 1986, would have been done without the benefit of GPS (and maybe even computational software) and based on control, remote from the site, determined by “traditional geodetic methods”. Experience with SPCs at that time was not universal. That could possibly apply to 1999 as well. For example, there are a number of Oklahoma Certified Corner Records that were prepared by the DOT in the 1970’s that have (purported) NAD 27 positions on them. Generally those positions aren’t worth the paper they are written on. They may get you to the right road intersection. But relative one to another they are useful data.
So I can forgive the pre-GPS surveyor for their shortcomings in that area. Nevertheless I agree that the degree of incompetence in the area of SPCs among modern surveyors is ….disappointing.
Several years ago I suggested on the message board du jour that that the NGS (or anybody else) should intitiate a project along the lines of CFEDS to train surveyors to a level of competence in the area, and provide some sort of testing and certification of same.
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Posted by: @mark-mayer
SPCs determined in 1974 & 1986, would have been done without the benefit of GPS (and maybe even computational software) and based on control, remote from the site, determined by “traditional geodetic methods”. Experience with SPCs at that time was not universal. That could possibly apply to 1999 as well. For example, there are a number of Oklahoma Certified Corner Records that were prepared by the DOT in the 1970’s that have (purported) NAD 27 positions on them. Generally those positions aren’t worth the paper they are written on. They may get you to the right road intersection. But relative one to another they are useful data.
So I can forgive the pre-GPS surveyor for their shortcomings in that area. Nevertheless I agree that the degree of incompetence in the area of SPCs among modern surveyors is ….disappointing.
Several years ago I suggested on the message board du jour that that the NGS (or anybody else) should intitiate a project along the lines of CFEDS to train surveyors to a level of competence in the area, and provide some sort of testing and certification of same.
I agree with ya buddy.
When I started to “seriously” deal with SPC data (and projects) back in the mid-70s, it was a bit of a grind. But nothing that a weekend or two with some decent reference books, an HP35, and a stack of legal pads couldn’t put into perspective.
In those cases where I could get my hands on the original Field Books (or copies thereof), a few hours of cal-ka-late’in proved that the field crews collected very good to excellent data, that was turned into doggy do do by someone in the office.
I find much the same thing today with GPS/GNSS or Total Station data, but nowadays mishandled software is weak link. This is of course USUALLY the fault of the computer operator, not the data or software itself.
Loyal
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Published values are SPC, Scaled to ground….. Ha ha ha
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SPC or officially adopted LDP coordinates would be a good thing for any state to adopt.
Wish Iowa would encourage it, as I have yet in my limited experience to see anyone putting coords on the records.
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Posted by: @nate-the-surveyor
Published values are SPC, Scaled to ground….. Ha ha ha
That’s the catch. You have to get people trained to know and record which they have (with g/g factor if needed). I’ve seen enough plats that are ambiguous on distance and seem to actually be SPC distances to know that you wouldn’t be able to trust corner records SPC without some more training. A good reason for states to have an official LDP.
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I’ve preached for years that any coordinates and/heights published without associated confidence info or metadata has all the integrity of a boundary line shown on Google Earth – just a wild a** guess!
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I’m hopeful that SPCS 2022 in many States, including Texas, will be LDP. If so, Loyal, you will have been a big part of the impetus for it.
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I still don’t understand why we are clinging to the 20th Century idea of State Plane Coordinates. In the 21’st century none of us are routinely manually calculating anything. That time consuming calculation were the only reason to pretend the earth was flat. Arguing about scale factors should be as antiquated as learning to use a slide rule.
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Are they not lost corners, so you just move on to the next available corner? Having correctly located same you may in fact be able to determine from record evidence of found and missing that the information given you does have some use. Sometimes surveying is not as easy as you would like, but you are still obliged to do it right.
Paul in PA
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Posted by: @paul-in-pa
Are they not lost corners, so you just move on to the next available corner? Having correctly located same you may in fact be able to determine from record evidence of found and missing that the information given you does have some use. Sometimes surveying is not as easy as you would like, but you are still obliged to do it right.
Paul in PA
Lost?
No, I don’t believe that is the proper terminology.
Obliterated!
Yes, but with conflicting “ties” to extant accessories (ie. nearby Corner Monuments).
The “trick” is determining (and verifying) which spatial data set constitutes the BEST Available EVIDENCE, with which, one can re-establish the Original Corner Location.
“Doing it right,” is using ALL available evidence/information (spatial or otherwise) to establish the location of the Original Corner, not dropping back to punt (treating it as LOST), and generating a new position, that in all likelihood, is NOT the Original Position.
Just my two bits.
Loyal
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Posted by: @paul-in-pa
Are they not lost corners, so you just move on to the next available corner?
That’s the trick. They aren’t lost, because they have been referenced out to remote SPC monuments and datum. But they aren’t really, because the work has been screwed up. So Loyal is left in sort of a no man’s land between lost and obliterated, waiting for the sword of Damocles to fall when somebody pulls the correct references out their rear end.
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Existent and obliterated seem to be almost the same thing the way I read it. I’m not certain why they bifurcated “found monument or at least acceptable evidence of where it was.” The old Lost standard before 2009 was just license to the GLO/BLM to save money and trouble by allowing proportioning unless the obliterated monument could be proven to an unnaturally high standard.
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metadata
collect it, preserve it, publish All of it.
Physical Monuments in the NGS system … which ones are you using, and which published values (including epoch) are you using?
Lat/Lon is native… the shake and bake into some moving SPCS is fraught with error…
Few of us learned much Geodesy and the maths to use it.
sorry if I am off topic with my rant
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@peter-ehlert
Agreed. It still boggles the mind that SPC are generally viewed with suspicion (rightly so) by surveyors…because other surveyors have f’ed up the computations and published bogus values so often.
We, the alleged professionals whose are supposed to be experts (or at least knowledgeable) on these things.
And not knowing the math(s) is no excuse any more. With the array of software and resources available to us (the NGS is not only helpful but free!) reducing and documenting coordinates and datums is a snap.
In my experience, the folks who complain about not being able to use the programs because they are “too complicated” are the same ones who turn up their noses at formal education. Formal education that includes courses like….geodesy…
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman -
I guess I lack “formal education” having no degrees.
It is not rocket science.What little I learned was mostly self study and from my mentors/coworkers… calculating with pencil and paper… later with a Calculator
we are all prideful, human nature.
Buck it up and learn.button pushing software is really cool… but we need to either defer to the true Experts or Learn the basics.
the content from Schools and credential to obtain Licenses… often lacking.Sorry for the continued rant. Happy Holidays to all.
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Dems State plain coords. Ahh just doan know what state day’s in!
Ahh stated it plain on me plat!
🙂
N
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Bill, Iowa does have a Regional Coordinate System (IaRCS) that is based on a set of 14 low distortion map projection zones. I participated in the database table definitions, working with Dr. Michael Dennis under contract to the Iowa DOT in 2014. The specifications document is here.
Rudy Stricklan, RLS
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Posted by: @rudystricklan
Bill, Iowa does have a Regional Coordinate System (IaRCS)
Sorry, I was too brief with my post, which was meant to refer to putting coordinates on corner records. Then other posts pushed mine further from the one I was replying to so the assumption of context was lost. I’m somewhat familiar with the IaRCS.
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The States will have ldp options, but the actual SPC zones will have too much distortion to be considered LDP.
NGS will have three layer options for each State. These will not happen on thier own and the process of development is well under way.
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