Wisconsin coordinate projection issue - XML/SDB

Multiple coordinate systems exist within Civil 3D for Wisconsin counties. WisDOT has provided coordinate systems in categories that begin with "WisDOT NAD83/". These categories include the Wisconsin County Coordinate System (WCCS) and the Wisconsin Coordinate Reference System (WisCRS), which are not equivalent, but very similar (typically < 0.01 ft difference). There are also two county systems in the "USA, Wisconsin" category that are preloaded with Civil 3D and other Autodesk software. The "USA, Wisconsin" category county systems are not equivalent to the systems provided by WisDOT.

Warning: When importing data into the survey database via LandXML, there is a field in the import options where a coordinate systems can be assigned to the XML file. If the survey database coordinate system and LandXML coordinate system are different, the survey data is transformed when it is imported into the survey database.

Since the county coordinate systems listed in the "USA, Wisconsin" category are not equivalent to each other, or to the WCCS and WisCRS systems that WisDOT has provided, users will see a transformation of their survey data when these systems are used interchangeably between the LandXML file and the survey database. The magnitude of the transformation can vary depending on the county and the project location within the county, but we have observed transformations as much as 3 feet. This occurs in all versions of Civil 3D.

Cause

Survey database coordinate system assignment does not match LandXML coordinate system assignment.

Solution

Make sure that the LandXML coordinate system matches the survey database coordinate system, or do not assign a coordinate system to the survey database or LandXML file.

Tip: To avoid confusion, or unintended errors, Methods Development recommends that coordinate systems should not be assigned to either the survey database or the LandXML file.

When the survey database coordinate system does not match the LandXML coordinate system, the survey data is transformed when it is imported from the LandXML file to the survey database. The exception to this is if either the survey database, the LandXML file, or both do not have a coordinate system assigned. In this case, the data will not be transformed when imported into the survey database. The transformation may have a magnitude of up to 3 ft. The following are example scenarios where a transformation can be expected or not expected.

Coordinate System Assignment #1 (SDB or Drawing)	Coordinate System Assignment #2 (SDB or Drawing)	Data Transformation?
No assignment	Any system assigned	No
Any system assigned	No assignment	No
No assignment	No assignment	No
Any system assigned	Same system as #1	No
*Category beginning with "WisDOT NAD83/": "WCCS-..."	*Category beginning with "WisDOT NAD83/": "WisCRS-..."	Yes (Typically <0.01')
USA Wisconsin Category: Begins with "Wisconsin County Systems"	USA Wisconsin Category: Begins with "Wisconsin <County name>"	Yes
USA Wisconsin Category: Begins with "Wisconsin County Systems"	*Any system located in the categories beginning with "WisDOT NAD83/"	Yes
USA Wisconsin Category: Begins with "Wisconsin <County name>"	*Any system located in the categories beginning with "WisDOT NAD83/"	Yes

Info: *The NAD 83 and NAVD 88 adjustment years for these coordinate systems do not affect the transformation. See Wisconsin coordinate system settings in Civil 3D for more information.

It is not possible to look directly at an import event in the survey database to see which coordinate system was chosen for a LandXML file import. To verify that the imported data was not transformed, choose a point in the survey database and note its coordinates. Then open the LandXML file in Notepad or other XML editing application. Find the point in the file and verify that the coordinates match what is shown in the survey database. If the coordinates do not match, re-import the LandXML file into the survey database without assigning a coordinate system to the LandXML file.

1. Is there a way to determine which coordinate system was used for the LandXML import event?

   No. The only way to determine if a coordinate transformation occurred is by comparing the coordinate values in the survey database with the values in the source LandXML file.

2. Will removing the survey database coordinate system assignment automatically fix the data transformation that occurred with the Import Event?

   No. The LandXML import event must be recreated. Also, the survey database points and figures will need to be re-inserted into the drawings.