I am currently working with a data set, which uses an unknown coordinate system from the south island of New Zealand, using x and y coordinates. I have these in an Excel sheet, but no further information on the coordinate system is known.
I have used Excel calculations and GPS approximations from Google Maps to translate the unknown coordinate system to the NZTM one, but the results still show a deviation of about 5km for some points. As I need to have very precise positions, I am thinking about using ArcMap to project the data points on a New Zealand map, adjust the points so it fits to the map and then use some kind of translation to get from the data points to e.g. GPS coordinates.
I've tried to illustrate that with the pictures bellow.
Picture one: The blue dots represent the x,y coordinates of the unknown coordinate system. Is it possible to insert those data points into ArcMap like shown on the picture?
Picture two: The second step would be to adjust the data points s.t. it fits the New Zealand map. Is such an operation possible with ArcMap?
The last thing would be to use exchange the initial x,y coordinates with e.g. GPS coordinates.