GCS - Creation of a custom coordinate system
Hi All,
Does anyone have any experience with creating a custom GCS? I have successfully followed the tutorial linked - https://communities.bentley.com/products/geospatial/desktop/w/geospatial_desktop__wiki/27585/--create-a-custom-geographic-coordinate-system
I have a user defined coordinate system in place. I am able to edit the properties and create Datum and Ellipsoid properties.
I am looking to change the Coordinates to a new system on a local grid.
Does anyone know how this can be done?
Many thanks,
Ethan
For local grid it can be done using Helmert or Affine transformation. Helmert doesn't require Bentley Map to create new GCS.https://communities.bentley.com/other/old_site_member_blogs/peer_blogs/b/marc_thomass_blog/posts/setting-up-in-the-real-world-georeferencing-update
How to create Affine transformation from Helmert:
https://communities.bentley.com/products/geospatial/desktop/f/bentley-map-forum/193992/is-it-possible-to-save-a-local-transform-to-gcs-list/575033#575033
explanation:
(+) - Convert local coordinate system to standard - 2D conformal transformation - OpenCities Map Wiki - OpenCities Map - Bentley Communities
Hi Oto,
Thanks for the reply these links have been very usefull.
I am very stuck on getting the Values for Helmert A and B.
As shown in the image below these are the values I have for the Scale factor, X and Y.
Do you know what values I need for the Helmert A and B?
Once I have these values I then need to do another equation to fill in the Affine parameters.
Helmert A is scale factor. Z is offset by Z axis, mostly unused.