Ability to override transformation extents when defining transformation paths
Hi @SisselS,
Thank you for your suggestion. ArcGIS Pro’s on-the-fly transformation capability is designed to provide users with quick and appropriate datum transformations without requiring deep knowledge of the underlying methods or which transformations apply to specific geographic areas. ArcGIS Pro assumes that the transformation path listed at the top is the most likely appropriate choice.
Allowing users to override defined extents would expose them to an overwhelming number of transformation options—potentially several hundred in some cases—and make it easy to apply an incorrect transformation path to the dataset. Since many users are not familiar with the details of datum transformations, this poses a significant risk and increases the likelihood of incorrect choices that could corrupt or invalidate their data.
That said, we recognize that there are specific scenarios where bypassing extent checks may be necessary—for example, when repairing corrupted datasets, working with outdated coordinate reference systems (CRS), or correcting previously misapplied CRS and transformations. For these cases, we offer a more controlled and permanent solution that GIS administrators and data managers can use to bypass extent restrictions and fix their data appropriately.
The Project tool in ArcGIS Pro allows users to manually define custom transformation paths. The tool only verifies that the transformation sequence correctly passes through all required geographic coordinate systems but does not enforce area-of-use constraints. For instance, in the example provided bellow—transforming Austrian data from ED50 to WGS84 (via a Norwegian transformation), and then to Belge 72 (via a Belgian transformation)—the Project tool successfully applies the specified transformations.
Please note that this approach only works with mathematical transformation methods, such as position vector or coordinate frame (7-parameter) transformations. Transformations that rely on grid-based methods, like NTv2, will not transform coordinates outside the used transformation grids.
If you believe the validity of the mentioned transformations or geographic coordinate systems should extend beyond what EPSG currently specifies, please reach out to EPSG (https://epsg.org/dataset-change-requests.html) and request a correction.
Thank you,
Bojan
