This is a reminder about how to apply a ground to grid correction in ESRI ArcGIS when dealing with coordinated geometry. Most survey plans will be submitted in Magnetic North but sometimes surveyors will use True North, Grid North, or locally defined North. A correction needs to be made in ArcMap, otherwise problems begin to occur over long traverses whilst registering the parcel in the pending subdivisions layer. The directions and distances in your GIS data are always based on the spatial data's coordinate system, or the grid measurements.
This arrow would be pointing to Magnetic North.
ESRI helpfile on COGO or Coordinated Geometry is located here for ArcMaps 10.1
Activating The COGO Toolbar
Ground To Grid Corrections
Click on the
Ground to Grid Correction button.
This brings up the main window with two options to make the correction.
If you have the survey plan in front of you, then use the first option as it will prompt you to enter the bearing and distance on the plan, then click on two known points on the spatial dataset. The application will automagically make the correction and applying it to all future bearings and distances.
The second option is if you have both bearings and distances as layers and you click on the map the ground lines for both plans. More help here.
Important: Remember to disable this correction when you are done!!! Just uncheck the tool or click