MAGNET Field - Setup Base on Known Point

I cannot be certain with this because I’m talking from Trimble experience, but my assumption would be that it cannot get the necessary global coordinates based on your Northing/Easting… even though they are state plane.  If you drop that N/E file into your software then export the file for your data collector it should come with the global as well…. 

or if you just do a “here” and get a file to correct the global, you could key in those same NE if need be.  All the projection parameters should make your points line up after that. 

localize all our projects

You mentioned using a state plane projection and a localization in the same project. This is your problem. Choose one and stick with it. You are not understanding how datums work. Pocket3D is the same way. You can't have both.

I'm confused. If you (your firm) set all the control points and you have all the coordinates, and the job is in state plane...

(a) why not set up on one of those points rather than set a new one from a single RTK observation?

(b) why not use the state plane coordinates that were established for those control points?

It seems that something is missing here, or your firm is making the process harder than it should be.

I am attempting to setup and start my base (Topcon GR-5) on a known control point. We have established control points for an upcoming job that are in state plane coordinates. I entered the northing/easting/elevation for all these points. Prior to me attempting to setup my base/rover our surveyor set up his equipment and shot a base point for me to setup on. However, when I attempt to start the base and choose a known point from the point list, it says "Coordinates could not be converted".

 

We localize all our projects via control points and the above order of operation is how we setup on each job, but we cannot figure out how to start from a known point in Magnet. The process is extremely simple in Pocket3D. 

 

Any help is appreciated

If the job was localized then you would need the calibration loaded in the job. I've had to do this with Trimble by putting the .jot file in the correct folder. Not sure on magnet as it's been a while since I used it. If I'm wrong someone will correct me. 

One way that works in Trimble...maybe also possible in magnet....if I need to create a new job with a calibration, I can go into the previously used calibrated job and then start a new job using "last used job" template and then it will load the site calibration. 

If your base point is unlocalized state plane try these settings before setup. 

If I had your base state plane coordinates I could give you the grid to ground settings (localization) for your job configuration.  

Sometimes there is a mismatch between Geoid models and that will stop the unit from working, it might be as simple as the data base in the office calling the model GEOID 18 when in the DC it's called Geoid18. 

Other simple corrections such as the DC set in State Plane west zone instead of east zone. 

There should be no localization or calibration preformed using a State Plane control network. The DC should be using the projection parameters established for that zone, calibrating warps that projection and is highly inappropriate. If the state plane network laid out doesn't conform to the projection parameters for that zone there's something wrong with the control and it needs to be fixed. Especially one done by the firm. 

You either imported or keyed-in your coordinates into a job file setup as local ground datum. Then you changed the datum to a state plane projection and tried to setup base on one of those coordinates. The software can't compute Geographic coordinates from your ground coordinates.  Start a new job file. Set the SPC datum. Import your coordinates and setup base station. Do not perform Localization. Stake out to several points and verify. 

@rover83 I’m still fairly new to this and I mainly assist the person who has done this for a very long time. We perform localizations on all our jobs even though we are typically given 2-4 control points by the company who designs the jobs. We are a general contracting firm so we mostly deal with GPS, machine control, and 3D model building. 

I was personally unaware that we could be using the state plane coordinate system within magnet when starting the base on a new job. I have since spoken to support and they got me the geoid files so I’m going to go out and test this out at some point without localizing as it’s apparently not necessary. 

I appreciate all the help everyone. 

as I mentioned in a previous reply, we have always performed localization from points given to us by the engineers/surveyors that design the job as we are a construction firm. 

I was not aware we could simply be using the provided control points that are in state plane coordinate system, and setting up without localizing. Our surveyor, my boss, claims they’ve never used the state plane coordinate system as it is not accurate enough. 

I am still new to this field and very much new to Magnet Field, having just completed a training on it last week. 

Thanks again everyone. 

@leegreen is there any varying degree of accuracy between a localization and using state plane coordinate system? We have always just used Pocket3D, setup on a known point that my boss shoots in with his system, and localized. But we are given survey control in state plane coordinate system for nearly every job to my knowledge.

s there any varying degree of accuracy between a localization and using state plane coordinate system?

Yes there is. If you have state plane coordinates,  then use the projection. With a localization you are introducing unwanted error by letting the software recompute the scale factor, rotation and transformation. You have been trained wrong, and unfortunately this is common procedure by many. If you measure just one point differently or the pole us not plumb, or if a point is disturbed, then the computed parameters are changed dramatically to try to best fit the geometry. This will distribute error throughout the entire site.

Our surveyor, my boss, claims they’ve never used the state plane coordinate system as it is not accurate enough. 

Around the area it says you are from the accuracy difference between the inverse of state plane coordinates and the horizontal ground distance is between 0.01 and 0.02 ft. In 1000 ft. For most construction this can be absorbed in the error budget. If the control you were given by the design firm is state plane the expectation should be that it is as accurate as it needs to be. However a place to start is to validate that outside the framework of localizing. 

Lee knows way more about machine control than I do, or than I want to learn. But, all the people I give control to that use machine control calibrate or localize. I've had discussions with them and they insist that they have to do it to make their systems work. So I would hesitate to advise you to do anything different than what your bosses are telling you to do. 

I've never understood the need to only calibrate but it seems to be nearly universal in the machine control industry. 

@ctrunkle

I was not aware we could simply be using the provided control points that are in state plane coordinate system, and setting up without localizing. Our surveyor, my boss, claims they’ve never used the state plane coordinate system as it is not accurate enough.

Good advice from others upthread.

If someone else did the control work (and got paid to do it), futzing with the published coordinates before staking is asking for trouble. Use what is published on the control sheet along with the coordinate system stated on the control sheet, and then check to ensure that they are within tolerance.

If there's a problem and things are not checking out, it's on the firm that set the control to fix it - and I say this as someone who quite frequently sets, adjusts, and publishes control for construction.

As Lee said, whacking a localization on top of state plane coordinates is far more likely to introduce unwanted error than simply using the coordinates given in the project coordinate system.

The lone exception would be if you are given no metadata whatsoever about the control coordinates, or they are shown as "assumed" or "local" system with no transformation parameters to go from a defined projection (usually state plane) to that local system.

In other words, if the coordinate system can be set up by punching it in on the collector rather than calibrating....just do that. It's far easier and less likely to screw things up.

Lee knows way more about machine control than I do, or than I want to learn. But, all the people I give control to that use machine control calibrate or localize. I've had discussions with them and they insist that they have to do it to make their systems work. So I would hesitate to advise you to do anything different than what your bosses are telling you to do. 

I've never understood the need to only calibrate but it seems to be nearly universal in the machine control industry. 

The main reason why this happens is these construction crews are trained by the Equipment dealers or resellers, which are not surveyors. The equipment dealers only know one way (localization/calibration). Try asking them how to load a Geoid. They don't understand. Identifying or reducing errors while maintaining accuracy is not on their plate. The overall goal of the equipment dealer is to sell, which in the end means eliminating many tasks of the surveyor.

There are probably a few things at play with this GC, their "surveyor" (boss), and how they do work:

In my experience, GC's get burned (liability) worst with 1d (height) vs. 2d. It's relatively easy to see if you're off horizontally, but not so much vertically, IF they don't do checks. (But then you have to figure out what the problem is and solve it if there is a discrepancy.)

Understanding and using geodesy can be difficult. 

The GC probably operates under the assumption that SPC is a 3d system, when it is not. And that is probably where the statement of "it's not accurate enough" comes from, referring to the potential for error in the vertical.

Does every GC employ a licensed surveyor worth their salt that has full command of all things geodesy? Do all of their operators know all things geodesy? No.

It sounds like the GC has a 3rd party provide control. Does this party know what they're doing? Did that party provide the design files (DTM, breaklines, etc.) to the GC to load in their machine control devices? Were those files on published mapping projections, etc.? Were they on a published vertical datum? Who knows?

None of that would matter to a GC who gets all that information, and then calibrates/localizes their machines to one or more local site points provided by 3rd parties.

In this context, it makes sense that they go out and do what they do, the way they do it. And it makes sense that the GNSS sales people dumb it down so far that, "if you do this, you can be really sure you won't muck things up too bad".

Myth, legend, and "I knew a guy that screwed it up that way" are a much harder things to overcome than finding good help and training staff. And that's why companies can't/won't/don't find good help or get the proper training.

Generally machine control is in state plane or UTM. Theirs no need to localize for grading around the site. The only time I would use “site coordinates” is for any layout and locations where precision is a must. 

I would have to believe that most of the reasoning behind the process we use is for machine control. At any one point in time on our jobs we typically have at least one base/rover running, several 3DMC equipped machines, and sometimes even MMgps. I know we will not change the localization process, even if I explain that the state plane coordinate system is accurate. It’s just as easy for us to localize on our data collector, export the project file and throw it into all the machines on site. 

It is interesting to me that we essentially wouldn’t have to localize, rather just start our base on a random point and then check in to the provided control, shoot the point we intend to use as a base and go.