Defining the Projection of a Vector Feature Class
Included in this tutorial:
Using the Define Projection tool to assign a coordinate system to a feature class
Software version in examples: ArcGIS Pro 2.8.0
Tutorial Data: This tutorial uses the 1:50m Admin 0 - Countries shapefile downloaded from Natural Earth.
Natural Earth. “Admin 0 - Countries.” [shapefile]. 1:50m Cultural Vectors, version 4.1.0. 25 May 2018. Accessed 28 June 2021 from https://www.naturalearthdata.com/downloads/50m-cultural-vectors/
Credits: L. Meisterlin with Erik Strand, Moses Levich, and Thiago Lee (2021)
This tutorial demonstrates using the Define Projection tool in ArcGIS Pro. The tool assigns coordinate reference system information to a feature class (a shapefile) that is missing this information.
Defining a Projection
If an input dataset has missing coordinate information, use the Define Projection tool to specify the correct CRS for the data.
In this example, the .prj file (the file containing the projection and coordinate system information) associated with the Admin 0 - Countries shapefile has been deleted.
warning generated by ArcGIS Pro when a dataset missing spatial information is added
When data missing its spatial reference is added to a project, ArcGIS Pro will show a warning message (shown at right).
Access the Define Projection tool in the Geoprocessing Pane under Toolboxes (tab) by clicking through Data Management Tools > Projections and Transformations > Define Projection (or by using the search function).
The Define Projection dialogue box will appear within the Geoprocessing Pane, with several parameters:
Choose the input dataset missing its projection information.
Choose the coordinate system to be applied to the layer. This data’s original CRS was WGS84, so select this CRS.
IMPORTANT NOTE: Unlike the Project tools (covered in Reprojecting Spatial Data), the Define Projection tool adds new information to an existing feature layer. It does not create or export a new dataset.
defining a projection for a layer missing its projection information