This old can of worms again...Grid or ground distance labels on property

My way of working:
State Plane coordinates are in true (no modified systems)
Distances are expressed as horizontal surface distances (99% of the time)
Bearings are in Grid or related to some local meridian

Metadata clearly explains each. There are some exceptions. If I'm following an existing modified Grid system, then I use the existing system, with metadata that explains the steps to true State Plane. On rare occasion, I will label grid distances, but this is an imaginary surface that only in rare circumstances coincides the Earth surface, and most clients are not interested in this imaginary surface. To be clear, the State Plane Coordinate System exists for our (surveyors) convenience, but is not without limitations. Foisting those limitations (labeled imaginary grid distances don't match historically used horizontal surface distances) on our clients seems unreasonable to me.

Bearing relations in my part of the country have been historically sloppy. The difference between State Plane and Geodetic North in my area is 2å¡. For most surveys, it's user's choice.

You've missed the most important reason to have good coordinates and clear metadata - and it has nothing to do with importing GIS data. When we publish coordinates in our cadastral work, we are giving the most sophisticated means of retracement ever to have been developed in the history of the world. Any knowledgeable surveyor, with minimal effort, can go on the ground and retrace my footsteps within a tenth of a foot, putting him on the cap on the rebar in most instances. That's not possible with sloppy management of the data.

So from a technical perspective is your CAD file in SPC with just labeled ground distances?

4) Use a LDP defining scale factor to minimize distortion at project ground, distances are ground, coordinates can be easily converted to any other system (State Plane, UTM)

tomchurch, post: 393152, member: 10174 wrote: So from a technical perspective is your CAD file in SPC with just labeled ground distances?

Yes.

Nearly all of my clients only care about ground distances and areas, so that's all I really care about, too.

Dan Dunn, post: 393154, member: 911 wrote: 4) Use a LDP defining scale factor to minimize distortion at project ground, distances are ground, coordinates can be easily converted to any other system (State Plane, UTM)

Best of both worlds.

tomchurch, post: 393144, member: 10174 wrote: We do three main project types, 100-500 acre boundary surveys, transportation engineering surveys (ranging from one intersection to miles), and local residential/commercial surveys.

It seems through my archive reading that most people are of the opinion that if you put something in SPC you should be consistent and label grid distances (if not convergence corrected bearings). I believe that Joe Paiva is also a proponent of this. It also seems that the consensus is that if you are not going to fully work in SPC you should put the coordinates far away from SPC. The problem is that clients often reject this. They want ground distances and areas on the their property and ROW maps. At the same time they (and we) also want it to be related (at least closely) to SPC in order to insert GIS data, to use RTN GPS (with limitations), and for indexing and other GIS purposes. They also often ask for SPC coordinates on control and corners.

I like the idea of working in SPC in my CAD drawings and in the field (we don't have a ton of elevation relief). The data collectors can automatically calc scale factors for each setup or make use of a project scale factor. And it makes things much easier considering the amount of RTN GPS and GIS data we use these days. But I also agree that property areas, labels, etc. are and have historically been tied to ground distances and areas. Grid distances and areas can and do cause confusion among attorney's, local municipal officials, property owners, appraisers, etc.

I see a few options 1) Do all my CAD/Field work in SPC but label ground distances/areas to keep clients happy, 2) Do all my work in ground and best fit it to GPS control for GIS purposes (but I can't report coordinates since they will not be actual SPC) 3) Do all my work in SPC with grid distances and areas (and spend the rest of my days arguing with clients). Of course whatever I do will be clearly noted on the mapping and in CAD files.

How do you approach this situation?

Here is what we do.

Notes:

1. All coordinates listed herein are expressed as grid coordinates referenced to and a part of the Texas Coordinate System, South Central Zone, North American Datum of 1983 (NAD 83), (CORS) 2011 adjustment, Epoch 2010.00.
2. All bearings shown herein are referenced to and based upon grid north as defined by the Texas Coordinate System, South Central Zone, NAD 83.
3. All coordinates as shown heren were derived from GPS observations conducted during August 2015 and August of 2016.
4. All distances shown hereon are ‰ÛÏsurface‰Û distances and may be converted to grid by applying a combined factor of 0.999870017

In Georgia, surface distances are required on boundary surveys. I will show the surface distances and areas. When a state plane coordinate is shown, we will have a note stating that all distance are horizontal and that a Combined Grid Factor of ________ must be apply to determine state plane coordinates.

Holy Cow, post: 393162, member: 50 wrote: Nearly all of my clients only care about ground distances and areas, so that's all I really care about, too.

Boundaries should almost always be reported in ground coordinates. Bearings should either be "true", or based on a record bearing. Land owners could care less what their property would look like if it was projected and rotated onto some imaginary surface.

Grid coordinates or lat/long should be provided as supplimental information to help future surveyors and GISers.

Some of our boundary clients want SPC coordinates shown on the mapping. It seems to me that working in SPC and labeling in surface distances is best for many boundary situations where only paper prints or PDFs are being delivered. I think I'm now more concerned about engineering surveys because they always get CAD files as a deliverable from us. They want control ties and coordinates in SPC and they always want it close enough to use GIS data. That said I don't think many of them know to design in SPC when it starts to matter on bigger projects.

Tom

Jack Chiles, post: 393172, member: 24 wrote: All distances shown hereon are ‰ÛÏsurface‰Û distances and may be converted to grid by applying a combined factor of 0.999870017

Good except that you should go ahead and replace the word "applying" with "multiplying them by"

My drawings and other data files are adjusted in relation to directly observed distances by a TS.
Actually, locally there is very little difference between grid to ground to report.
I show north observed from the site of the project, either by GPS based on WGS84 or sun shot.
:8ball:

For me State Plane Coordinates, Ground distances, and Magnetic bearings (with declination from grid north on plans). I do almost exclusively boundary work in the New England Area.

I show ground distances on my boundary surveys for a number of reasons, the chief of which being that that is how all the surveys have been done around here forever, and I don't want to add any more confusion to the existing record than I have to.

I don't like using pseudo state plane coordinates in my drawings, but as others have stated: "The clients want it". I work for engineers. They don't want to work on the grid in the drawings because Civil 3d has always sucked at handling state plane coordinates well (in relation to data links, xrefs, points, etc.). They do want to be able to xref in GIS data, aerials, etc to be coordinate correct. What I do these days is calculate a combined project scale factor, move the coordinates so one point on the job matches, then truncate my control that I list on the survey (with true state plane coordinates also listed for major control points, scale factor, and convergence angle). The drawing itself stays in pseudo state plane. Of course, I have true state plane coordinates for all the control and found monuments, since I run them through starnet, if I need them for a Land Corner Record, DNR Permit, or Record of Survey. I'll link one I just did.

Again, I don't feel that this is a perfect system, because I know someone will open one of my drawing files without bothering to read my notes, decide incorrectly that the drawing is in state plane, and thereafter cause themselves and others much confusion. I would rather create and use a Low Distortion Projection. Unfortunately, the area I work in is very hilly, I haven't been able to make one that I'm happy with yet, and I've had trouble in the past with custom projections in C3D (same issue as with state plane - the wheels fall off when you try to xref and data reference drawings and point data between multiple engineering drawings). This is the best I've come up with, utilizing the existing technology at my disposal.

I'd love to see examples of what other folks do.

We work on the ground, and report all data on the ground (the SPC grid is about 7000' below us). I have never been asked and I never have displayed coordinates of any sort on a boundary survey.

On a number of topographical or monitoring well surveys where I have been asked to provide grid coordinates, I have run into extreme confusion by my clients. I had a national environmental engineering firm tell me that my grid coods were ground and vice versa. After educating them for weeks they told me that I was right, and they were wrong, and that EVERY job they had performed for YEARS was done incorrectly. Since then I have tried desperately to keep the ammunition out of the hands of those who don't have a clue what it is or how to use it.

Let's talk about it.
IF you publish in SPC, somebody will want "ground". If you publish in "ground", somebody will want SPC.
So, who is going to "USE" your plat?
You? Another Surveyor? An engineer? Architect? Fisherman? Cowboy?
MOST surveys in Arkansas are published in "ground". Since that is what they are "used to".
I have decided to (at least for now) publish in "ground". And, place one or 2 SPC coords on the plat. All the metadata. In short order, somebody could PUT it all on SPC.
But, I could also publish in SPC, and also add metadata, and let others convert to ground.
I really don't care what you do, so long as there is enough metadata to convert.
And, my suggestion is to use whatever format that MOST users of the plat will be using. ie, make it less work for others.
My two cents...

N

It is okay to put grid and ground observations on the map. In fact I prefer it.

Each line can be labeled with both grid and ground distances. Each point displayed can have a unique identifier, like a point number.

Then have a list or table with a full description for each point and an explanation of how the coordinate system was established.

I don't have a difficult time explaining that to the client.

Years from now when the points need to be recovered or right now when the survey map needs to be geographically referenced the map will facilitate.

I find this much better than trying to geographically locate some local arbitrary coordinates of a rectangle in a subdivision of 300 rectangular parcels. Sometimes the only information given on the map is the name of the former owner for whom the survey was performed.