Why are CAD files exported from ArcGIS Pro with the Export to CAD tool misaligned in AutoCAD?

Answer

CAD files added as feature layers in ArcGIS Pro and exported using the Export to CAD tool are slightly misaligned when compared to the original CAD file in AutoCAD. This happens fundamentally due to the way computers interpret and process floating point numbers. A floating-point number is a whole number (positive or negative) with a decimal point.

When viewing CAD data exported from ArcGIS Pro using the Export to CAD tool in AutoCAD, data conversion takes place to convert the data's linear unit. During this conversion process, the coordinate values are recalculated. Data conversion happens in AutoCAD when the data exported from ArcGIS Pro is assigned to a linear unit other than the US Survey Feet unit. This occurs as the data by default is assigned to the US Survey Feet unit in AutoCAD.

For example, when false easting values (starting with even values of the meters unit) of the State Plane Coordinate System are converted to a US Survey Feet linear unit, the converted measurement returns an odd value. One feet is equal to 1200/3937 meters, or exactly 0.30480060960121920243840487680975 meters. This value is considered an infinite, non-repeating decimal, which is an odd value.

The linear unit data conversion causes the recalculation of coordinate values. Therefore, feature locations in CAD data exported from ArcGIS Pro are slightly misaligned when viewed in AutoCAD.

As a workaround, create a CAD seed file (.dgn) with the same measurement unit as the spatial data in AutoCAD and input the file in the Seed File parameter when converting GIS data to CAD data using the Export to CAD tool. Refer to ArcGIS Pro: Export to CAD (Conversion) for more information.