# Unknown coordinate system need in Lat/Long degree format

I received CAD data from PDs and the data they gave is already geocoded (which is great) and it reads well when I add it to my map on ARC map. However, the format is as follows (x = 632086.7, y = 1043211.35) I need them in the following format (x = 33.867022, y = -112.1409750) so that I can use it in R. My first question is what is the original coordinate system format? I've tried identifying it but I haven't found something that is helpful. Second question is, how can I transform the first coordinates into the second format?

• "PDs" should know the projection your/their data is in. You will need to know this to re-project this into lat/lng.
– Mapperz
Mar 20 '17 at 20:18
• Where are you located? It is often possible to determine the projection of the data given a few pieces of information. Your location is the first piece. Next would be if you can tell whether the data is in feet or in meters. Last would be some idea of the age of the data, or the source of the data. Some sources always use the same projection, like UTM or State Plane in the USA. In general, the more information you can provide about your situation, the more likely it will be that someone can answer your question, or put you on the right track to figuring it out yourself. Mar 20 '17 at 20:23
• I am in AZ and the example coordinate provided above is a readable lat/long in arc map. I was able to turn on the points using a State Plane NAD 1983 HARN projection and when I do this the points plot well onto a base map. However, in trying to change the conversion notation format through the tool in ARC map the current/raw format is not recognizable. I am trying to change the first format into the second format. I was also hoping to be able to figure it out first before going back to the PD because it will likely take a bi of time before they get back to me. Mar 20 '17 at 20:45

I'm assuming you have points.

It sounds like you have already identified the native coordinate system of the CAD data as NAD 1983 HARN State Plane Arizona Central (international feet).

However, you want to get the latitude-longitude values for features instead.

I think you'll have to convert the CAD data into a feature class or shapefile. Once you do, you can use the Project Tool to create a copy in NAD 1983 HARN (geographic coordinate system) then use the Add XY Coordinates tool to populate two fields in the attribute table with the latitude-longitude values.

Note: latitude = y, longitude = x in ArcGIS

Another method is to leave the feature class in State Plane.

1. Add the feature class to ArcMap.
2. Change the data frame's coordinate system to NAD 1983 HARN (open data frame properties, coordinate system tab, select geographic coordinate systems, north america, NAD 1983 HARN).
3. Open the attribute table.
4. Add two new fields set to type double.
5. Right-click a new field and select Calculate Geometry.
6. Select X Coordinate or Y Coordinate.
7. Select use coordinate system of the data frame.
• Thank you!!! This gave me the quick transformation from feet to decimal degrees... Would you or anyone else know the code to transform coordinates in ft to decimal degrees in R? Mar 20 '17 at 23:20
• You can use spTransform in R, so do some searches here for some examples, and then maybe ask a new question. Mar 22 '17 at 18:55