Convert Ground to Grid Data in GIS

ChrisHart1

I am trying to develop a workflow to convert data that I have in ground NAD83 UTM Zone 12N, conversion factor 0.999855, to UTM NAD 83 Zone 12N Grid.  Whenever I use the regular projection tools, it does not move the data. I have to always manually move it by reference points.  What is the best way to approach this?  Thanks!

MelitaKennedy

Try defining a custom projected coordinate system for the 'ground' data. If the ground UTM coordinates are supposed to be multipled by 0.999855 to convert them to regular, grid UTM coordinates, modify the PCS parameters like this:

false easting: 500000.0 / 0.999855 = 500072.5105

false northing: Zero so keep set to zero

scale factor: 0.9996 / 0.999855 = 0.99974496302

All other parameters remain the same. If you right-click the NAD83 UTM Zone 12N in the coordinate system picker, you should be able to choose Copy and Modify. In the new window, 

Change the PCS name. 

Modify the 2 projection parameters.

Save as a .prj file.

Use the Define Projection Tool or ArcCatalog to assign this definition to your ground data.

Melita