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.