Create custom geographic transformations based on the Canadian Geodetic Survey's NTv2 format

Summary

The Canadian Geodetic Survey (CGS) developed and maintains the NTv2 tool (National Transformation version 2) for performing geographic (2D) coordinate transformations between NAD27, ATS77, NAD83(Original), and NAD83(CSRS). The transformations in this tool are based on Grid Shift Files (.GSB file type) defined for specific provinces of Canada. While these transformations ship with the supplementary ArcGIS Coordinate Systems Data software component for ArcGIS Pro and ArcGIS Enterprise, users may need to generate custom versions of them for use in other applications. The Create Custom Geographic Transformation (Data Management) geoprocessing tool can be used to generate custom .gtf files based on .GSB files downloadable from the Natural Resources Canada website.

Procedure

1. Identify which .GSB file(s) to download from the Natural Resources Canada Coordinate Transformations web page. For example, for transforming data located in the province of Alberta between NAD83(Original) and NAD83(CSRS) epoch 2010.0, download ABCSRSV7.GSB. Note that an account is necessary to access the files.
2. Open the Create Custom Geographic Transformation (Data Management) geoprocessing tool in ArcGIS Pro.
3. Provide a Geographic Transformation Name, and set the Input Geographic Coordinate System, for example, NAD 1983/WKID 4269 for NAD83(Original).
4. Set the Output Geographic Coordinate System, for example, NAD 1983 (CSRS) v7/WKID 8255 for NAD83(CSRS) epoch 2010.0).
5. Set the Custom Geographic Transformation type parameter to NTv2.
6. Browse to and select the .GSB file downloaded in Step 1 by clicking on the folder icon.
7. Optionally, define an extent.
8. Run the tool.
9. The .gtf file is added to the custom transformations folder, for example:

C:\Users\<USERNAME>\AppData\Roaming\Esri\ArcGISPro\ArcToolbox\CustomTransformations

Note: 
This workflow can be used to generate custom NTv2 transformations for data in regions outside of Canada, provided that the .GSB file is obtained from an authoritative source. The NTv2 format was originally developed by the Canadian Geodetic Survey (CGS), but has been adopted for use in other countries.