Rotated Local Site Coordinate System to State Plane

[cssmith]

I have a site that operates on a local coordinate system that is rotated almost 30° off grid north. I want to create a transformation between this local system and state plane to be able to export CAD linework and points to state plane locations.

So far, I have modified a projected coordinate system based on the site calibration file from the survey team.

These settings seem to have the correct scale and coordinate values, but there is still the issue of the 30° rotation.

Next I tried to create a "translate and rotate" under the "Create Custom Geographic Transformation" tool. Molodensky Badekas is only one that seems to provide the translate / rotate options.

After this, it gets kooky. I can't zoom in closer than 1:2,000,000 scale, so I can't even tell if it worked or not. From what I can see, it doesn't look like the rotation worked either. There is very little documentation (that I have found) trying to do this, so I am at a loss where to start troubleshooting.

Any advise related to the zoom issue and the Create Custom Geographic Transformation tool appreciated.

[ThomasHoman]

Hi,

Can you share a few things? 1) full site calibration report? 2) some sample points along with their State Plane correct locations?

We might be able to use the Hotine oblique Mercator azimuth center to define the projection for a long term solution - it takes the standard Mercator projection information and adds the pivot coordinate along with the rotation value. This would allow you to go back and forth with the surveyors. Check out https://desktop.arcgis.com/en/arcmap/latest/map/projections/hotine-oblique-mercator.htm 

If this is a one off need, then consider the Transform Tool - https://pro.arcgis.com/en/pro-app/latest/help/editing/transform-a-feature.htm 

Regards,

Tom

[cssmith]

Tom, thanks for the help. I've attached word doc has screenshots of all the information I have for site calibration (I don't believe there is official report anywhere) and two csvs of survey control, one in the local system and one in NAD83 (2011) Texas State Plane N Central Zone 4202. I will look into the Hotine Oblique Mercator.

[ThomasHoman]

Building the projection but can you also have the survey guys try this on assumption they are using Trimble TSC7 or TSC10 controllers? https://www.nrcs.usda.gov/sites/default/files/2023-03/Exporting%20a%20Survey%20Shapefile%20-%20Surve... 

These are the steps to export the job points to a shapefile.

Just a thought.

[ThomasHoman]

I tried taking your data and rebuilding the site calibration in Trimble Business Center but couldn't get it quite right. Calibrations are funky things and considering I had 0ppm N and E slope these points you provided earlier are not the point pairs that they built the calibration from.

Maybe the PRJ files in my 2 passes will get you close enough.

[cssmith · Accepted solution]

Thanks for the help! I believe I found a work around that works just as good. I am mainly working with CAD data in the local system, so I georeferenced my main dwg using two of the local and state plane points. This does the simple translate and rotate I was attempting to do. The cool part is the "Save to Workspace" option that creates a universal world file, so any CAD dwgs in the same folder location is applied the same transformation.