Hi,
The idea assumes to have an option to be able to modify already defined GCS in the PlantSight. Currently this option doesn't exist. Ideally worklfow would allow User to switch coordinate systems (in case if we have project where is used mobile entity). Idea discussed with PlantSight Team internally in Bentley. For more details please contact me directly: mateusz.jaworski@bentley.com
There is an effort ongoing currently with the iTwin Platform team about Coordinate reference systems and the importance (or not) about being about to "change" the CRS in a specific iModel. I know we have the ability today to "display" alternate coordinates in PlantSight however we don't have the ability in ANY iTwin application today to change the already set CRS - this would be a platform change required.