topic Re: Best Way to Programmatically Identify a Coordinate System? in Civil 3D Customization Forum

Best Way to Programmatically Identify a Coordinate System?

CodeDing — Tue, 06 May 2025 20:19:43 GMT

Hey all,

Looking for some guidance here. The overarching question is:

What is the best way to programmatically identify a coordinate system?

I understand that there are Projected, Geodetic, Arbitrary, etc ...Coordinate Systems. So perhaps for sake of taking a first step, the question could be:

What is the best way to programmatically identify a projected coordinate system?

It should also be assumed that enough information necessary to identify the coordinate system is present (e.g. Ellipsoid name/flattening/radius/etc, Projection scale/false northing/false easting/etc, Datum name/realization/etc). Also, the data can be in any format necessary (JSON, XML, WKT, etc).

So even if I have all of this data, HOW can I programmatically (using any programming language, ideally .NET or Python) output, with ##% confidence, something like:
- EPSG 2232

- Custom CS, based on EPSG 2232

- Arbitrary CS

I would like to ultimately retrieve this information from a source, open Civil 3D, and automatically assign a coordinate system (assuming I have sufficient information/confidence to do so).

As always, any input is appreciated.

Best,

~DD

Re: Best Way to Programmatically Identify a Coordinate System?

rampseeker — Wed, 02 Jul 2025 02:24:56 GMT

I retrieve the coordinate system code using this method

[CommandMethod ("printCoordinate")] public static void PrintCoordinateSystemCode() { var doc = Application.DocumentManager.MdiActiveDocument; var ed = doc.Editor; var civDoc = CivilApplication.ActiveDocument; // getCoordinateSystemCode string csCode = civDoc.Settings .DrawingSettings .UnitZoneSettings .CoordinateSystemCode; if (string.IsNullOrEmpty(csCode)) { ed.WriteMessage("\nNo coordinate system is set for this drawing."); } else { ed.WriteMessage($"\nCurrent coordinate system code: {csCode}"); } }

Re: Best Way to Programmatically Identify a Coordinate System?

CodeDing — Wed, 02 Jul 2025 02:52:12 GMT

@rampseeker ,

Thanks for the reply! I can easily get the CS Code with the System Variable CGEOCS. My main goal is rather identifying a system by all of it's definition properties. In essence, if I had everything BUT the CGEOCS code, how would I determine a CGEOCS code lol

Best,

~DD

Re: Best Way to Programmatically Identify a Coordinate System?

Anton_Huizinga — Wed, 02 Jul 2025 09:39:02 GMT

You can request the current Coordinate System with this code:

public static acDbServ.GeoCoordinateSystem GetCurrentCoordinateSystem() { acDbServ.GeoCoordinateSystem returnValue = null; string name = string.Empty; acDbServ.Database db = acAppServ.Application.DocumentManager.MdiActiveDocument.Database; using (acDbServ.Transaction tr = db.TransactionManager.StartTransaction()) { try { if (db.GeoDataObject != acDbServ.ObjectId.Null) { acDbServ.GeoLocationData gd = tr.GetObject(db.GeoDataObject, acDbServ.OpenMode.ForRead) as acDbServ.GeoLocationData; Match matchName = Regex.Match(gd.CoordinateSystem, "<Name>(.*?)</Name>"); if (matchName.Success) { name = matchName.Groups[1].Value; } if (name != string.Empty) { foreach (acDbServ.GeoCoordinateSystem cs in acDbServ.GeoCoordinateSystem.CreateAll()) { if (cs.ID == name) { returnValue = cs; break; } } } } } catch (System.Exception ex) { } tr.Commit(); } return returnValue; }

The returned object can be read further, if I remember correctly, you can see if it is projected and read the WKT stuff and so on.

If you want all 6000+ available Coordinate Systems, you can use this code:

public static List<acDbServ.GeoCoordinateSystem> GetAllValidCoordinateSystems() { List<acDbServ.GeoCoordinateSystem> returnValue = new List<acDbServ.GeoCoordinateSystem>(); List<string> ignoreItems = new List<string>() { "obsolete", "deprecated", "replaced by", "for testing only", "incorrect", "legacy use" }; foreach (acDbServ.GeoCoordinateSystem cs in acDbServ.GeoCoordinateSystem.CreateAll()) { if (cs.Type == acDbServ.GeoCSType.Projected) { string description = cs.Description.Trim().ToLower(); if (ignoreItems.Any(s => description.Contains(s)) == false) { returnValue.Add(cs); } } } return returnValue; }

Re: Best Way to Programmatically Identify a Coordinate System?

CodeDing — Wed, 02 Jul 2025 11:31:55 GMT

@Anton_Huizinga ,

That's useful information! I'm semi familiar with retrieving the CS Dictionary XML data. Perhaps this would be one step of the entire process. But my question would still remain:

If I had everything BUT the CGEOCS code, how would I determine a CGEOCS code?

It's a very nuanced question and definitely not easy to answer.

Best,

~DD

Re: Best Way to Programmatically Identify a Coordinate System?

Anton_Huizinga — Wed, 02 Jul 2025 11:40:10 GMT

I guess you could walk through all available CS and then compare as many as values.