I believe the state plane system did exactly what it was intended to do. It was designed to keep math simple in the days of mostly hand calculations so the plane mapping system to keep things as close to geodetic as possible. The only thing the ground had to do with it was reducing the distance along the surface to ellipsoid. Surveyors on the boundary side and construction side nor engineers accepted that geodetic as the gospel. On the non geodetic surveying side we kinda play its flat enough or close enough. Which at the time the first state plane system was put in the difference of grid and ground was negligible because of the chaining and poles Also the system was perfect at that time for highway projects and the like We have simply out grown the system because we can position things within such a tight tolerance over miles and miles today. But we still have to give a large amount of credit to those who designed the system because it still works today if it’s applied correctly. It actually could be simple to i theory just do everything in state plane period design boundary etc etc And yes that would make some properties just shrink in size but it could be done. And yes we need to follow in the footsteps as well which can be done also the one thing that always gets mentioned is the distortion from ellipsoid to the plane grid or from geodetic north to grid north. We have to be on ground because of distortion Well let me open a can of worms If you think surveying on ground is not distorted then you are fooling yourself . It is the very reason we have professions of geodesy and geodetic surveying etc we have just accepted that surveying on ground is more accurate subconsciously I guess . Now we are developing a system that the distortion will be smaller at the ground to grid level in areas but further from the geodetic datum . Maybe LDP is the best answer. Have a datum that everyone is required to tie to period and simply instead of assuming 5000 5000 create a ldp on every job and that way when junior gets the project next door he can see your ldp information and it will all tie on the datum side I mean they created the system in the 1900’s this thing state plane if used correctly is awesome But it boils down to time = money No way around it i see And not everyone has the education to understand it either There are some top notch surveyors probably still out there today that have more brains than i could ever but they might have never ever use a system like state plane i knew several that had been around and every job was the same assume north 10000 east 5000 and run around a boundary hold a plat bearing and then everything was on that forever throughout design etc . Maybe we could design a new unit of measure that had a scale in it that could be the fix lol call it something we have 2 feet had several definitions of the meter change. Chains veras hands poles . Wheels how far a horse could walk trot I am amazed after working all over the world and seeing different coordinate systems designs datum’s mapping projections used etc . I mean the people who did these things are some very intelligent people and they had enough compassion to create a system for a dummy like me to understand .
"And yes that would make some properties just shrink in size but it could be done."
How would using state plane make a property shrink?
At the time the SPCs were designed, they probably didn't have the data in m manageable form to design LDPs. A card file of coordinates and elevations is not like a computer data base. Even with the data the calculations to find good parameters would have been arduous.
If that had been practical at the time, I imagine they would have done it.
A couple of inches per half mile tends to add up. Seriously.
One guy lists a distance of 2639.41 between monuments and the other guy says it's 2639.57 between the same two points. One creates the description and the second comes along later and reports all description distances are off by varying number of hundredths. One is writing descriptions in State Plane, the other one is using direct measurements with a total station.
@mathteacher if we are on grid the mapping projections. The distances are shorter so the square feet will be less and acreage will bel less numerical not in physical. Than if we measured the same lines at ground. Also this gets to the understanding of mapping projections themselves. No one mapping projection can hold all truths. Size shape distances directions. If one is aware of what mapping projection they have and where what all is needed is equal area direction etc. and where it is not then it again is simple math. I can’t remember now but take a larger area and simple square and compute the area length x width at grid. Then do same at surface. I believe the math is square of the combined factor or squared root of it divided or multiplied to do the same thing as we do with distances. Not all properties are square and not all are at same elevation around property. For a long time i never even carried elevation assumed or otherwise on just a boundary survey. I have one coming up that id did a rough check on that i would affect the acreage enough that i will have to do my computation for the acreage at ground. I guess poor grammar here of stating property would shrink could have been clear. Not physically the property would be what it would be. But using grid distances to close it would change the numerical value vs same thing at surface or ground.
One is writing descriptions in State Plane, the other one is using direct measurements with a total station.
Using SPC distances on a plat WITHOUT NOTINGTHEM as such should be cause for disciplinary action. Doesn't every state call for ground distances?
I'm close to you on RX0088, I get 4.57 ppm, but we're pretty far apart on RX1056.
I think it's west of the airport with distortion of -147.5. It's 1,000 or so meters higher than RX0088.
It's a good example of what @mightymoe is talking about. It's also a good example of how a standard state plane distance calculation can be advantageous in mountainous terrain.
That's what I get too. I gave you the wrong station. I was looking at one 12 miles east at a lower elevation. Please don't take this wrong. It might be advantageous in a mathematical sense but not necessarily a practical sense for reasons or excuses already made.
But that's the point of this whole discussion. NAD83 is not designed for measurements on the grid to be equal to measurements on the ground. It's impossible to create such a projection for an entire state.
To use state plane, you have to first understand that the plane is not the topographical surface. Then you have to know how to convert between the two. That is why we have scale factors and elevation factors.
A calculation of acreage using state plane distances shouldn't even be considered; it's meaningless.
But state plane distances won't always be less than ground distances. Beyond the lines where the secant plane intersects the ellipsoid, grid will be greater than ground.
No problem. Thanks for testing that hastily designed LDP.
The topography changes rapidly out west. We have a little of that here, but 5,000 feet here is exceptional, 2,500-4,000 fairly common.
Any LDP in the Rockies is bound to be limited in size.
Iowa law requires distances on the horizontal plane whatever that means. The only plane defined in the survey code is state plane but absolutely no one practices using that definition. It's assumed to mean a horizontal plane at whatever point the total station is at. In the case of GNSS usage its assumed to mean a project plane approximating ground.
I would say limited in height more than size. You could create a sizable LDP that could include a number of mountain tops for example.
I'll bet all this talk amuses Loyal. He's Mr. Mountain LDP before it was cool.
Yes. Where there are saddlebacks that aren't swaybacks, it would work fine.
As you know, rapid elevation changes kill LDPs and ground coordinates computed from state plane coordinates. On the NC coastal plain, we could probably do a 50 mile by 50 mile LDP with no problem.
We could perhaps do something reasonable between Boone and Blowing Rock.
But between North Wilkesboro and Boone, probably not.
@mathteacher i 100% agree. That is correct that is what you asked originally. The issue is that some do not look at state plane coordinates the same way they were intended to be used. Reality is i see surveyors use them as if they are just coordinates and not on a mapping projection. I know they can use them correctly they have already proven they perform the math as they use similar equations every day. But it’s that maybe they are in such a hurry or don’t want to i have no idea. I stay in the dog house all the time as i make the necessary computations when i process jobs. But i have to deal with the issues on projects that are not mine and were not done the correct way and it becomes a this is how we always do it and that’s the way it should be done. It is very productive to devise a system that everyone does the same exact thing same exact steps on pushing the same exact buttons. And this stuff was established these procedures before some of the software could do it so easily like we have had for many years and today. So for some it doesn’t matter that Trimble Business Center or any other software can compute this so easily. Heck microsoft excel is easy enough also. Its just thats what was done and in surveying bucking the system is frowned upon at company levels. I was almost fired once because I discovered a company had duplicated tempature and pressure settings in total station and data collector then apply it again in office. So triple . It didn’t matter that both the data collector manual and total station manual specified that use one or the other. It was the way it was always done. I agree the math the process is not hard and i am not the brightest bulb myself. But I always said if i can figure it out anyone can. If the system is used as intended its one of the most accurate ways we can measure and position things next to true geodetic work. I am no cad guru so maybe thats the road block. I have worked on both sides geodetic and daily ground surveying. I didn’t not see the why a system like state plane was so great until i had done geodetic work. Utm and others. Once learned and saw how to handle everything the light bulb shined and now personally if i were solo i would simply do everything in a state plane and do whatever computation’s necessary to meet the state specific standards. I have followed one surveyor here that had his required coordinates in a certain county on the plat that i would say were true state plane. His bearings were state plane grid and his distances were ground and he had a good set of meta data notes etc that when i followed him it was only a difference of my measurements vs his and that was all within the rtk tolerances and traverse tolerances. So so minute it was negligible. Most of what I follow i see they have scaled to ground but publish the state plane ishhhhh coordinates as required and i can follow the boundary nothing wrong with the boundary information but the coordinates have a shift and sometimes i wonder if they know exactly how far they are shifted. I usually reverse engineer it and see if i can determine hiw they scaled. Some scale from a zero zero location and a combine factor for a county. Some scale in centroid of the property at an point and elevation not necessarily the average elevation or ellipsoid height. Some pick a point. Some use spreadsheets but most are not scaling distances they are scaling the northing and easting coordinates. They have spreadsheets set up to do this. I have asked . Now it doesn’t change the boundary survey just the coordinates themselves. And yes some probably have done this on jobs that a one combined factor is probably introducing distortion that maybe they don’t realize. I caught one of those approaches on a job i was troubleshooting. Once i showed the person why simply clicking in tbc at approximately the center of the site would not work in that situation they were like ohhhh. Now i see what you have been saying. I think the answer to your original question is not what is most understood but what is the most negligence use of the system might be better question. I think this has been a great topic for sure. I enjoy reading all the comments and seeing things. Remember i am told this all the time surveyors hate change. Look its 2023 and if it were not for rtk dominance a lot of surveyors would not be using state plane period. It would be as simple as setting up on a site assuming a north and east and off to the races. I started my career doing that using a compass for azimuth and or sun shots. Everything else was just assumed. Sometimes we just assumed north because we knew we were holding a certain line off a deed anyway.
OK, I see the problem between individual state plane distances converted to ground and CAD.
CAD is itself a plane coordinate system. It needs coordinates to draw lines. If we want ground distances out of CAD, we have to give it ground coordinates. If we use a single combined factor to derive the coordinates, the angles on the drawing will be state plane angles by geometrical similarity.
If different lines have different combined factors, CAD will have difficulty coping. Have to call in an AI shrink. The old plane table guys would throw up their hands and walk off the job.
Thanks for being patient with me. I had to make a lot of connections to get to the underlying cause.
Think of it this way, I recently did a subdivision of small lots kinda in the country south of town. These lots were about 8000sq ft. They were being offered at 120k. Seems crazy to me but I'm not the buyer. I do see houses being constructed there and they are nice looking. What the lots actually went for I don't know.
Anyway that's $15 per sq ft.
Using a state plane of 300ppm (6000' below ground) will change the sq ft per lot by almost 5 sq ft. Not a big deal, but that's $75 per lot, 150 lots and you just cost your client $11,000. All cause of a state plane fetish.
So, to correct that, your idea is to recalculate all the lines surrounding each of the 150 lots. Probably doing that using strictly state plane coordinates will cost at least the $11,000 to hand enter each number, check all the calculations, ect.
In a small, flat, low state the difference is probably not noticeable.
I doubt I would ever be taken to court over the $75 per lot, but I feel like doing the best for my client is important.
Well, that's sort of my idea. I would actually divide each of those separate state plane coordinate lines by its own individual combined factor to get the same length that I would measure on the ground for each one. I wouldn't redo anything in this case, though.
Again, using state plane distances to compute acreage produces a meaningless number and you should know that. Surveying on the state plane grid does not mean using state plane grid distances as if they were on the topographical surface, and you should know that, too.
But, even if the surveying software could do that, which it probably can, CAD couldn't handle it.
With your method, you get something very close to topographical distances along with state plane azimuths. Measuring a lot line will produce the CAD result, but turning the angles won't.
And that is a plane geometry relationship, not a surveying truth.
@norm VA has similar wording. I asked the question once and was told that the standards stated ground. I am getting a beer soon as i won the bet lol. Around 1930 ish I found where it was added that all distances were to be reduced to a horizontal plane. No where does it state ground. Prior to the 1930’s ish. I am still trying to do the research but many surveys were along the slope especially when measuring with poles up a hill. Not uncommon for any area I imagine. My date is approx. i was studying and came across the topic and lead me down the rabbit hole. I like researching this stuff. Anyway if one wanted to make a good case to argue with the way the standards are written one could probably do very well in arguing that since the state plane was adopted at about tge same time all horizontal distances were required that surveying on the ground could be a mistake from Assuming. And we should have all been on plane. But historically the surveys were on ground. But I imagine one of those good smooth talking lawyers could make a good argument either way. It was drilled into my head we measure horizontal distance at the surface for boundary work. We have approached the time in which we can measure so well and it’s not slowing down either. Can you imagine one can survey 20 miles a part and have confidence that those two points are within an error ellipse of a coke bottle top. Now to traverse that far if we fell within the come bottle itself we would be tickled pink.
Just off the top of your head, how long after each 150 lot is drawn and labeled would it take you to hand calculate each line, relabel them by hand, check it all somehow for errors and typos?
Remember, at the time you start the effort I'm already finished with the exact numbers and $0 for the client.
Now, Moe, I said above that I wouldn't change anything that's been completed. And you don't have the exact numbers; they're probably within a few hundredths or thousandths, but you really don't know, do you?
I'm not criticizing your work, but I do object to considering surveying on state plane to mean using grid coordinates as if they were ground.
Can you tell me the ppm error in any of those lines? Is it the same for all of them?