I have 8 shapefiles which have a common coordinate system but none of them have it defined i.e. "unknown" is written when I look in the properties dialog box. However, I can see the extent which I am sharing here:
Top: 42.349145
Bottom: 41.710962
Right: -82.430463
Left: -83.126193
I need to define the projection of these shapefiles so that I could do further analysis. I know that the features these shapefiles represent are located in Windsor, Ontario i.e.they should have a projection of WGS 84 UTM Zone 17N. Can I directly define this projection without knowing about the geographic coordinate system?
Best Answer
The values are in decimal degrees. That makes it harder to identify the actual coordinate reference system, because the values are so close. It's a lot easier to differentiate between a UTM and a MTM zone. If the data was collected recently, they may be in NAD 1983 CSRS.
On a related note, the Define Projection tool and the data's property page in ArcCatalog allow you to assign the current coordinate reference system. They update the metadata, not the actual values of the dataset. The data has to be georeferenced / in that coordinate reference system already. To create a new dataset in another coordinate reference system, you use the Project Tool (but the input data must have its correct coordinate ref system!).