Welcome aboard Mr. Burkholder...
This thread could benefit from some adult supervision, and a fresh view of the issue(s).
BTW, I have your article from Surveying and Land Information Systems (Vol.53, No.1, 1993) right here on top of my desk as I type!
Loyal
Some State Plane History
> I would try and explain what:
> "using a projection that more closely matches what the PLSS..."
> Means, but I'm afraid that [in your case] it would be a waste of time and band width.
Translation: it just means that grid north will be sort of North-ish. You've already explained how you use it as a quick'n'dirty aid for corner search.
Welcome to the board.
jud
SP Coordinates, maybe not so obsolete
> 6. Although state plane coordinates are very useful in come cases, the fact remains that map projections (state plane coordinates) are a two-dimensional model and we work with three-dimensional data. That makes state plane coordinates obsolete.
That would, of course, be true if land boundaries weren't entities that may be exactly mapped onto the plane projections of the State Plane Coordinate Systems. However, the actual case is that virtually all land boundaries that have a definite position also have a definite position on those projection surfaces.
I trust that it will be admitted that any land boundary corner that has a definite spatial position on the Earth also has a definite latitude and longitude independent of ellipsoid height, for all practical purposes, and therefore has definite grid coordinates in any of the mapping projections used in the SPCS.
Mr. Burkholder
I would like to ask if a surveyor was to prepare a topo and boundary in autocad based on the GSDM how difficult would it be for an engineer to use it for his design. This is probably a very simple question but it would not be of much use for us to change to a different system if it was not useful and economic.
Kent
"I trust that it will be admitted that any land boundary corner that has a definite spatial position on the Earth also has a definite latitude and longitude independent of ellipsoid height"
Simply NOT true in some cases. All sorts of "rights" (and ownerships) can (and often do) have vertical limitaions and even boundaries.
Don't try and project (pun intended) your Texas paradigms outside of your own comfy little pond. State Plane Coordinates are not, and never really were, the perfect solution (there probably isn't a perfect solution). Technology moves forward, not backwards, and things change whether you like it or not.
Loyal
Kent
> "I trust that it will be admitted that any land boundary corner that has a definite spatial position on the Earth also has a definite latitude and longitude independent of ellipsoid height"
>
> Simply NOT true in some cases. All sorts of "rights" (and ownerships) can (and often do) have vertical limitaions and even boundaries.
Sure, there are exceptions such as air rights, view corridors, approach surfaces, and underground easements, but as a practical matter, my statement is true since those special cases probably represent fewer than 0.1% of property boundaries.
SP Coordinates, maybe not so obsolete
Ever see this equation?
X^2 + Y^2 + Z^2 = D^2
It's the 3D version of Pythagoras Theorem. Since the earth is about round and we have entered the age where we are doing things in a roundabout way (GPS), the third dimension matters even if you believe you will be sued out of business for putting a height on a survey plat.
That's why SPC's are becoming obsolete. The measurements and math to go 3D are all easily done with modern software.
If you want to calculate the exact distance between two points from SPC's you must have the height. Maybe the real distance doesn't matter just as the actual bearing (on a round earth).
SP Coordinates, maybe not so obsolete
> Since the earth is about round and we have entered the age where we are doing things in a roundabout way (GPS), the third dimension matters even if you believe you will be sued out of business for putting a height on a survey plat.
>
> That's why SPC's are becoming obsolete. The measurements and math to go 3D are all easily done with modern software.
Obviously, you didn't bother to read my post. Land boundaries that have definite positions on the Earth's surface are also entities that may be mapped exactly onto the projection surfaces of the SPCS. Likewise, entities on the projection surface (i.e. having exact grid coordinates) may be exactly transferred to the surface of the Earth, subject only the the characteristic errors of the measurement and positioning processes used. That is why the State Plane Coordinate Systems remain perfectly functional for land surveying.
SP Coordinates, maybe not so obsolete
Walking is a functional way to get from New York to San Diego but not many folks do it all the time. I'd take a plane unless I had all summer with nothing else to do.
SP Coordinates, maybe not so obsolete
> Walking is a functional way to get from New York to San Diego but not many folks do it all the time. I'd take a plane unless I had all summer with nothing else to do.
Yes, why not take the State Plane?
SP Coordinates, maybe not so obsolete
I'll give you some sense of humor. Taking the state plane would work also but how many times would you need to land, change planes and take off again. There would also be some calculation confusion to get across the airport.
Maybe what we need is just one all states plane projection system. Why complicate it with many. There shouldn't be any limits on the distortion inducted. Maybe just suspend the plane and simply use lat and long. Why the need to even back lat and long out of the SPC. The lat and long gets you there to the point on the earth's surface doesn't it? Simple and functional!
Anyway time to stop wasting the bytes and bandwidth on this stupid argument.
SP Coordinates, maybe not so obsolete
> I'll give you some sense of humor. Taking the state plane would work also but how many times would you need to land, change planes and take off again. There would also be some calculation confusion to get across the airport.
No, that's the beauty of the State Plane. Its schedule is reliable and well known. It's those Private Planes that cause nearly all the problems.
Mr. Ellis,
You asked a good question and there is a good answer. The GSDM provides local flat earth coordinates with respect to any point you name as the origin. They are obtained from the ECEF coordinate differences by a rotation matrix whose equations are straight forward. I'll reference several items FYI:
1. The local flat earth coordinates (latitudes/departures) are taken from the P.O.B. Datum box in http://www.globalcogo.com/BK001.pdf
2. The original defining document (as do other items) has all the equations. See http://www.globalcogo.com/gsdmdefn.pdf .
3. I wrote a series of three articles for plane surveyors that were published in the Professional Surveyor magazine in 1997 and 1998. See http://www.globalcogo.com/psgsdm.pdf .
4. I have posted an example of using GPS and the GSDM to perform a control survey and section breakdown. See http://www.globalcogo.com/3DGPS.pdf .
The "no distortion" item (#4 above) lists the P.O.B. datum values (lat/dep) with respect to the SW corner of the section. The flat earth distance from the tangent plane to each point could also have been included in the table (but the example is a 2D plat).
There are other examples posted as well. Enjoy.
Incidently, how does one post the little postage stamp photo with a submission?
Regards to all.
Earl F. Burkholder, PS, PE
Click on your name,
... then "edit profile".
Under "Avatar", edit or add the picture that you choose to be your avatar.
Thanks for your input on this recurring subject and welcome to the forum.
I am sure there are many here that share my hope that you will continue to participate.
GB
Thanks for the links I will be reading them , not making any promises I will understand a lot of it - took me forever to get the diagram of geoid, ellipsoid, and ortho heights straight in my head.
> Thanks for the links I will be reading them
Robert, if you find any advantage whatsoever to any of that over simply using the Texas Coordinate System of 1983, please be sure to mention it.
Earl,
Welcome to the board. Your input here and your contributions to the profession are greatly appreciated. When I was at OIT we were using some of your previous papers and info and I have many of them in my reference material.
Jered
I would like to highly recommend Mr Burkholder's book to anyone interested in this subject. A great reference and very enlightening.
Marrakesh John
GSDM
Has your GSDM system been directly ported to any of the standard field computers like Trimble, Topcon, etc?
You probably have a good thing but it needs to be available to the masses of surveyors to ever go anywhere.
Can it be implemented through one of the standard projections available on most survey computer systems?
