Comments on: ArcGIS Projections: “Define Projection” and “Project” https://gisgeography.com/arcgis-projections-define-project/ Geographic Information Systems Mon, 31 Mar 2025 11:49:28 +0000 hourly 1 https://wordpress.org/?v=6.9 By: GISGeography https://gisgeography.com/arcgis-projections-define-project/#comment-1808 Sun, 05 Feb 2017 19:34:39 +0000 http://gisgeography.com/?p=1088#comment-1808 In reply to Ashi.

So if you add your data in ArcMap and get ‘unknown spatial reference’, does it end up in the correct location? You can add another data set and check where your data is located. If it’s in the right location, then you should run ‘define projection’ and there’s nothing else you have to do.

But let’s say you have another data set with a different coordinate system… you can use the ‘project’ tool to change your data set to the other coordinate system. This may mean you’ll have to do a datum transformation. Esri will project data ‘on the fly’ according to the first shapefile or geodatabases added in that data frame.

Hope that helps

]]> By: Ashi https://gisgeography.com/arcgis-projections-define-project/#comment-1807 Sun, 05 Feb 2017 08:45:14 +0000 http://gisgeography.com/?p=1088#comment-1807 If my data has no defined coordinate system. The ArcGIS error message would look like: “Unknown Spatial Reference”. In the next step, I use Define Projection Tool to give it a coordinate system (WGS_1984_UTM_Zone_47N). This creates a .prj, .tfw, .aux within my existing dataset.

My question

Next step, I run the Project tool in order to change the shapefile (output coordinate system WGS_1984_UTM_Zone_47N).

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