RTN Grid to Ground

Paul Quagge

New Member

I'm using a RTN and would like to know the process to set up a Ground Coordinate Project based on the Project I collected in State Plane?

I've reviewed the published process in the guide and read the comments on the Forum using a base station. I'm currently searching for the Mountpoints x,y and z assuming that would be the base?

Can anyone confirm this process?

Thank You,


Well-Known Member
Under coordinate systems you can the menu button and duplicate the state plane system then tap the pencil icon to adjust grid to ground.

There is a setting to save the vrs base point in setup. I can't remember excatly where off the top of my head. Not sure I would use the vrs base point for the scale point. I typically use a real point like a property corner or survey point. The VRS base point is imaginary.
This is pretty easy in J-field... I like it!

In your coordinate system choose the house looking button to add a new local site coordinate system:

Then give it a Local System Name and specify the underlying coordinate system of your local state plane zone:

Next choose the pencil looking edit button:

Then choose adjust Grid-to-Ground & Rename:

Then pick the target looking box to the right of your east origin...this gives you the ablity to choose the point where the Grid North / East will be coincident with the Ground North / East

I personally plan ahead so this point is the actual property corner on my plat where I show a tie line to a geodetic monument...(makes for a clean tie line with grid coordinates at each end...easily retraceable when the datum changes)

When you choose your point it should publish the value in the “Origin” & “Ground” fields as shown:

When you ok back to your project settings you will see the Project Coordinate System as renamed with the Ground scaler in parts per million:

I also have made it a habit to visit my pages to make sure the new ground scaled system is being applied to the pages:

Works real good...easy to repeat the process if you want to choose another point after you get into your survey planning.
Cool...yeah something I am passionate about seeing done well...
I’ll add one more thing...
When this makes it into CAD the only true “Grid” Coordinate is the point of localization at which you scale to ground in this process.

On my plats when I show my grid tie to a geodetic monument, I actually scale just that tie line by my project scale factor so that in my drawing it is actually a grid distance again rather than ground. Then I label each end of that line with the Northing and Easting...you can back check your work because the coordinate “should” match your NGS Data sheet...or be really close.
Then the distance on that line is labeled as (GRID) and I label the scale factor on it also.

This checks:
My coordinate system...units...scale factor...DPOS cors corrected position...etc.
Really a bullet proof workflow for a good project coordinate system.

Here’s a snapshot of how I label it...