topic Re: Coordinate System - Conversion in Coordinate Reference Systems Questions

Coordinate System - Conversion

ArifKassim1 — Tue, 25 Sep 2018 10:16:12 GMT

Coordinate conversion

Which is the best practice for coordinate conversion of the features / shape files?

I often use the following method

Import the xy from excel (know coordinate system)
Event layer to shape file
Data Management Tools --> Projections and Transformations --> Project - To get the output data in the required coordinate system selected.
Calculate Geometry in newly added fields to get the x&y values of new coordinate system

A second method :

Import the xy from excel (know coordinate system)
Event layer to shape file
Open a new map,
Assign the required coordinate system to the data frame
Add the shape file from step 2. into the new map with a different coordinate system and apply the transformation.
Calculate Geometry in newly added fields to get the x&y values of new coordinate system

I have tried both the methods and I get different x & y values.

#Coordinate conversion

Re: Coordinate System - Conversion

DanPatterson_Retired — Tue, 25 Sep 2018 10:30:26 GMT

the second method doesn't project the data...

You state …. apply the transformation. ….

hopefully you don't mean use the Define Projection tool... because it doesn't work... telling a file that it is something that it isn't is an error.

Method 1, where you specify everything directly and project the file overtly is the best method... there are variants, but for the nanoseconds difference, it really doesn't matter.

As for the shapefile... Destination should be a featureclass in a file geodatabase.

Export to shapefile if needed for other applications

Re: Coordinate System - Conversion

ArifKassim1 — Tue, 25 Sep 2018 10:46:16 GMT

The second method (in detail) after getting the shape file from step ii

Open a new map, and assign the required coordinate system to the data frame
Add the shape file which is in a different coordinate system than the above map from step ii in the new map
Geographic Coordinate Systems Warning - appears - Click transformations
Converts from: "the coordinate system of the shape file" Into: "the coordinate system of the data frame"
OK
Calculate Geometry in the newly added fields to get the x&y values of new coordinate system

Thanks for your comments.

Re: Coordinate System - Conversion

MelitaKennedy — Tue, 25 Sep 2018 21:21:29 GMT

Two things to check in your second workflow.

1. In Calculate Geometry, make sure to use the data frame's coordinate system

2. When you set the Transformation, make sure it's using the same transformation that was used in the Project Tool.

Melita