I would like to propose improvements to the Define Projection tool in ArcGIS Pro. The tool only updates some of the coordinate system information associated with a dataset. I would like to see it enhanced to change all the coordinate system information as well as the SRID on the geometry.
As per the documentation the DefineProjection tool "Overwrites the coordinate system information (map projection and datum) stored with a dataset. This tool is intended for datasets that have an unknown or incorrect coordinate system defined."
We have recently discovered that some of our spatial data has incorrect coordinate systems defined; datasets were defined as WGS84 while actual coordinates were correct for NAD83. Therefore, these datasets require an update to the coordinate system information (i.e. WGS84 to NAD83) while retaining the same coordinates. In this scenario, as we would like to update the coordinate system information while leaving the coordinate values as-is, we would leverage the Define Projection tool to update the datasets coordinate system information from WGS94 to NAD83 (and not the Project tool which would project the dataset from WGS84 to NAD83).
We have found that the Define Projection tool appears to update coordinate system information only partially, in that some properties are not updated to reflect the newly defined coordinate system information. Performing a copy/paste of a “partially redefined” dataset will result in the coordinate system information being updated fully, however this is not feasible for many datasets including those with versioning, archiving, or relationship classes.
Below is an example to demonstrate the effects of Define Projection tool used to take our dataset from Calgary_3TM_WGS_1984_W114 to NAD 1983 3TM 114, as compared to performing an additional copy/paste of the resulting dataset.
| 1 | 2 | 3 | 4 |
Layer | AB_CAL3TM | AB_CAL3TM_CHANGE | AB_CAL3TM_CHANGE_COPYPASTE | AB_NAD83_TEST |
Description | Unaltered Calgary3TM data. | Calgary3TM after Define Projection to NAD1983. | A copy/paste of the redefined NAD1983. | Unaltered NAD83 dataset for comparison. |
HAS M | N | N | N | N |
HAS Z | N | N | N | N |
Pro Properties SR | Calgary_3TM_WGS_1984_W114 | NAD 1983 3TM 114 | NAD 1983 3TM 114 | NAD 1983 3TM 114 |
Pro Properties SRID | 300002 | 300002 | 3776 | 3776 |
ST_GEOMETRY_COLUMNS | 300002 | 300002 | 3776 | 3776 |
SHAPE.SRID | 300002 | 300002 | 3776 | 3776 |
GDB_ITEMS_VW.PROJCS | Calgary_3TM_WGS_1984_W114 | NAD_1983_3TM_114 | NAD_1983_3TM_114 | NAD_1983_3TM_114 |
In this example we can see the Define Projection tool updates only the highlighted properties in green while the highlighted properties in red retain the old properties (1 to 2) whereas performing a copy/paste results in updating the remaining properties (3). The properties and values for a dataset created in the desired coordinate system is present for comparison (4).
Although we have not observed adverse effects of datasets in this state (2), we request that the Define Projection tool is improved to fully update the properties and values of a dataset with the desired coordinate system information, to the equivalence of a dataset created in the desired coordinate system (4).
