topic Does appending data from a different projection , reproject that data to Designated Projection? in ArcGIS Pro Questions

Does appending data from a different projection , reproject that data to Designated Projection?

AmandaLaur3 — Tue, 03 Feb 2026 18:48:57 GMT

If I have a feature Class in NAD 1983, and i would like to append data from a feature class , for example say UTM 15N, Does the data get reprojected into designated Feature Class projection along with the Append? Or should the data be reprojected before the append?

I have been trying to figure a way to analyze this, but since everything is ultimatley projected on the fly, it is hard to compare the differences.

Re: Does appending data from a different projection , reproject that data to Designated Projection?

Robert_LeClair — Tue, 03 Feb 2026 19:43:55 GMT

Appending data from a different projection in ArcGIS does not automatically reproject the data to the designated projection of the map or scene. Instead, ArcGIS Pro reprojects the data "on the fly" to match the coordinate system of the map or scene for visualization purposes. This means the data will visually align with the map's spatial reference without altering the original data's projection.

However, for analysis or editing purposes, it is recommended to permanently reproject the data into a consistent coordinate system shared by all layers. This can be done using tools like the Project or Project Raster tools in ArcGIS Pro. Reprojecting ensures accuracy and avoids potential spatial errors associated with on-the-fly projection.

Re: Does appending data from a different projection , reproject that data to Designated Projection?

AmandaLaur3 — Wed, 04 Feb 2026 15:25:48 GMT

I understand Projecting on the fly for Map and scene Visualization. I'm specfically referring to the Append Tool and the designated Feature class, not the map projection.

Regardless of visualization, If I am combining 2 data sets with the append tool, Does the Source Data set get projected to the Target dataset feature class within the append operation?

The Target Feature Class is NAD1983.

I am appending points from a feature Class that is UTM 15N.

Without even pulling into a a map/visualization, Are the appended points now reprojected to the target feature Class(NAD 1983), Or are they Still somehow in UTM 15N and Just appended without actaully recalculating Coordinate informaton.

Re: Does appending data from a different projection , reproject that data to Designated Projection?

Robert_LeClair — Wed, 04 Feb 2026 15:44:28 GMT

Understand - thx. On the Append (Data Management)—ArcGIS Pro | Documentation help page, there is a section that states: "The input and target datasets may have different spatial references. When this is the case, the tool projects the input features to the target's coordinate system. For best results, specify an appropriate geographic transformation using the Geographic Transformations environment. If the target dataset is a map layer, the tool may apply a default transformation. In Python, there is no default transformation."