原始线要素类为地理坐标系，如何获取以米为单位的距离？

            IPolyline polyline = feature.Shape as IPolyline;

         

            IPolycurveGeodetic polycurve = polyline as IPolycurveGeodetic;

            ILinearUnitEdit linearUnitEdit = new LinearUnitClass();



            //Define the properties for the linear unit 

            object name = Meter;

            object alias = Meter;

            object abbreviation = M;

            object remarks = Meter is the linear unit;

            object metersPerUnit = 1;

            linearUnitEdit.Define(ref name, ref alias, ref abbreviation, ref remarks, ref metersPerUnit);

            ILinearUnit pLU = linearUnitEdit as ILinearUnit;



            double distance = polycurve.get_LengthGeodetic(esrType.esriGeodeticTypeGeodesic,pLU);

int indexTBMJ = disCursor.FindField("TBMJ");

ILinearUnit linearUnit = DefineLinearUnit();

int count = 1;

foreach (var feature in disCursor.AsEnumerable())

{

    var polygon = feature.Shape as IPolygon;

    IAreaGeodetic areaGeodetic = (IAreaGeodetic)polygon;

    double geodeticArea = areaGeodetic.AreaGeodetic[esriGeodeticType.esriGeodeticTypeGeodesic, linearUnit];

    feature.Value[indexTBMJ] = geodeticArea;

    disCursor.UpdateFeature(feature);

    polygon.SetEmpty();

    (areaGeodetic as IPolygon).SetEmpty();

    Marshal.FinalReleaseComObject(areaGeodetic);

    Marshal.FinalReleaseComObject(polygon);



    if (count % 100000 == 0)

        Console.WriteLine($"{prefix}计算要素{count}个，耗时：{stopwatch.Elapsed}");

    count++;

}