State Plane Coordinates were originally designed so that Highway Departments (in particular) could utilize USC&GS Geodetic Surveys without having to delve into spherical trigonometry. Over the years the obvious advantages of using the SPC System became obvious to many other Surveyors and agencies far beyond just Highway Engineers. I spent many years surveying IN State Plane Coordinates around the West, and can attest to both the advantages and disadvantages of doing so (the advantages outweighed the disadvantages... EXCEPT when they didn't).
However, with the computational power provided by even the early micro-processors, and certainly the advent of GPS, the perceived need to circumvent what was once the onerous computations required to “tie into” the National Geodetic Network using Geodetic Observations & computations, evaporated. We no longer “need” the State Plane crutch to “tie into” the National Network.
Although I have been using LDPs since the late 70s for most projects, “they” (LDPs) are NOT the answer to EVERY “problem,” anymore than SPCs (or UTMs) are!
Not only THAT...
In the PLSS States, the Basis of Bearings for nearly ALL Land Titles are based the Astronomic Bearings of the Original GLO/BLM Surveys.
Virtually ALL of my boundary work is retracing PLSS and Mineral Surveys. ALL of these boundaries are based on True bearings and True Horizontal distances at the mean “elevation” of each line.
NONE of this work relates to SPC/UTM Grid anything! A properly designed LDP will more closely "approximate" those Bearings and Distance, but it is still an approximation.
In fact, I am getting real close to just returning my Record Of Surveys in “True Bearings & Distances” as per the 2009 Manual (which I have done before), and letting the chips fall where they may. No Grid-Ground, Gamma this, CAF that, rotation, scale, datum, realization, SPC/UTM Zone, LDP parameters, or other superfluous BS.
From this here monument (described) True (geodetic) Bearing, True Distance (USSF) to that there monument (described).
Maybe drop the Laplace value in there for the Astro boys.
There will (of course) be a tabulated list of NAD83(2011) Latitudes, Longitudes, and Ellipsoid Heights based on the latest NSRS, but in reality, IGS08 (de jour) XYZ (in meters) would serve the exact same purpose.
Loyal
> In fact, I am getting real close to just returning my Record Of Surveys in “True Bearings & Distances” as per the 2009 Manual (which I have done before), and letting the chips fall where they may. No Grid-Ground, Gamma this, CAF that, rotation, scale, datum, realization, SPC/UTM Zone, LDP parameters, or other superfluous BS.
>
> From this here monument (described) True (geodetic) Bearing, True Distance (USSF) to that there monument (described).
> Maybe drop the Laplace value in there for the Astro boys.
Just as a point of CURIOSITY, why wouldn't it be more USEFUL to annotate the map in grid bearings and grid distances of the SPCS and throw in the true bearing and distance at ground scale as an INFORMATIVE aside?
The main purpose of the true bearings and surface distances is JUST for comparison with the original GLO survey, isn't it? The SPCS grid bearings and grid distances would seem to be the most efficient way of putting the whole works on the MAP, so to SPEAK. :>
I'll say it again, the global spatial data model (GSDM) provides a simple efficient way to handle 3-D data (GPS, total station or both) without map projections, zone constants, grid scale factors, elevation factors etc. The GSDM (with fewer computations) provides local horizontal ground distance and true geodetic azimuth - both forward and back.
See articles on same on the Global COGO web site.
You may want to start with items #14 and #19.
If you have questions, just let me know.
Kent
The Original RECORD Description in the Federal Patent AIN'T in no SPC Grid!
Grampa homesteaded/claimed/bought the land that he could walk/farm/ranch/mine, as described in the patent that he has in the Family Bible. Not some esoteric polygon expressed on a developed surface a mile below his feet, and oriented to a theoretical point a hundred miles away.
B-)
Loyal
Kent
> The Original RECORD Description in the Federal Patent AIN'T in no SPC Grid!
Yeah, and the original RECORD didn't have none of them latitudes and longitudes on it, neither. As I'm sure you'll AGREE on reflection, there are two different issues. One is where the land REALLY is on the ground and the other is the EVIDENCE that connects that location to the original Government SURVEY. The true bearings and distances at (VARYING) ground scale are in the latter category.
Kent
Using the GSDM puts you right on the ground as you wish!
Earl
I hear Earl, and maybe someday we can all get on board a 3-dimensional system.
Unfortunately, GIS Folks, Realtors, and [some] Texans, are stuck in a 2-dimensional paradigm, despite the fact that the GLO surveys were 3D based for hundreds of years.
At least civil engineers understand a 2+1 spatial paradigm, which is a step in the right direction.
😉
Loyal
Kent
Face it Kent...you are trying to fix something that ain't broke.
😀
Loyal
Kent
> Face it Kent...you are trying to fix something that ain't broke.
Well, here's the situation. Your plan of giving true bearings and ground distances (presumably the AVERAGE SCALE of horizontal measurements at the endpoints of the particular LINE) is mostly just historical data for comparison with the original survey. So, it's basically a COMMENT or an ASIDE.
However, for making a record of GEODETIC POSITION, you want something better. Sure you COULD just list the geodetic coordinates of the various points on the line, but it is so much better to give bearings and distances that connect them in a form that is as readily usable as possible. The typical user is almost certainly going to want to PLOT the description that YOU'VE left for posterity, both to overlay it on aerial imagery and to verify the geodetic coordinates. The best plan is to facilitate THAT with the LEAST screwing around and across the most platforms. Hence the SPCS.
Earl
> I hear Earl, and maybe someday we can all get on board a 3-dimensional system.
> Unfortunately, GIS Folks, Realtors, and [some] Texans, are stuck in a 2-dimensional paradigm, despite the fact that the GLO surveys were 3D based for hundreds of years.
No need to wait Loyal. I mean, just because land boundaries are 2-dimensional entities doesn't mean that you can't map them as 4 or 5-dimensional things. The original GLO surveys were obviously not 3D. They were made in GENERAL DISREGARD of the fact that the Earth wasn't flat. Basically, as I UNDERSTAND it, the only thing that you're doing with a 3-D ground MODEL is estimating what you might measure with a perfect chain if you were to actually rerun a line on the ground. Naturally, you'll ALMOST invariably discover that your estimates AIN'T FITTING the record of the early surveys exceptionally well, so where's the BEEF?
Earl
Way back around 79 or 80 I got a program for one of the HP calculators that would calculate a traverse line geodeticly. You would input your start point, the elevation of the point, the nad27 AZ the vertical angle, the hi, oh and slope distance and it would calculate the lat and long of the next point. Then with another program you would input the lat long and it would give you the SPC. No more reducing the ground distances to plane distance, or converting lat longs to SPC by hand. Even then I was thinking it was time to move to geodetic surveying, not sure we ever will.
But you're preaching to the choir.:-)
Earth to Kent
I hate to be one to break the news to ya, but the vast majority of the aerial photography that I run into these days, is either in UTM or LDP coordinates, NOT in SPC!
Maybe Texas is different...oh wait...Texas IS different!
😛
Loyal
Obvious point
Well, the obvious POINT is that a description should allow the ready checking and generation of geodetic coordinates. What using grid coordinates and grid bearings does is facilitate that. Sure, if you provide a list of the LLH positions of EVERY point positioned by your survey, you could with the right SOFTWARE, inverse between them to see if the results match the true bearing and local surface distance that you provided. That would provide a check, but it is just more powerful and generally USEFUL to work in grid coordinates.
I mean, if you're complaining about folks trying to figure out something simple like a Combined Scale Factor, just wait until they get an OLSONIZED description to work with.
Kent
"Yeah, and the original RECORD didn't have none of them latitudes and longitudes on it,"
Hmm - every GLO Plat I've ever seen has a Lat. & Lon. ...
Kent
> Hmm - every GLO Plat I've ever seen has a Lat. & Lon. ...
LOL! If any of those are even within even a quarter mile of the same position in NAD83, I'd be surprised. What Loyal is talking about are accurate latitudes and longitudes that actually describe the positions of boundary corners, not some approximate position for adjusting the latitude arc on a solar attachment.