Gird-to-ground conversion

[johnsonj]

I have a sid image in state plane coordinates that needs to be adjusted to state plane GROUND coordinates. This GROUND adjustment is a local correction that is applied due to differences between the geoid and the actual local ground surface. Basically, all XY coordinates need to be multiplied by a factor (1.000197939). I tried to just update the sdw file, but then did not see any horizontal shift when viewing the file in ArcGIS. Is there some other file that needs to be updated, or is there a way to apply this correction in GeoExpress?
Thanks,
Jay

[rparker]

Hello,

GeoExpress will allow you to create, edit, and save your own custom coordinate system; however, I am unfamiliar with the conversion parameters you will need.