Why the PythonCall local polyconic reproject on LL27 gives incorrect results, but WGS84 give correct ones

I have a pythoncaller that does a local polyconic reprojection. The orgin point  is (sur_long, sur_lat,z) = (-87.9960175,28.6407318,0.0) and the point to be reprojected to (lat,long,z)  is (xoffset,yoffset,zoffset) = (0.0,0.0,0.0).  Here is the pythoncaller code:

 

 

class myPythonFactory(object):

 

    def __init__(self):

 

        self.count_features = 0

 

        self.logger = pyfme.FMELogfile()

 

       

 

    def input(self,feature):

 

        uwi = str(feature.getAttribute('WELL_ID'))

 

        surf_lat = float(feature.getAttribute('SURF_LAT'))

 

        surf_long = float(feature.getAttribute('SURF_LONG'))

 

        x_offset = float(feature.getAttribute('XOFFSET'))

 

        y_offset = float(feature.getAttribute('YOFFSET'))

 

        z_depth = float(feature.getAttribute('TVD'))

 

          

 

        #myCSMan = pyfme.FMECoordSysManager() defined in startup python

 

        fmeParamsp'PARM1'] = str(surf_long)

 

        fmeParamsn'ORG_LAT'] = str(surf_lat)

 

          

 

        myfmeCS = myCSMan.defineCoordSys(fmeParams, "myfmeCS")

 

           

 

        pointF = pyfme.FMEFeature()

 

        pointF.resetCoords()

 

       

 

        pointF.setDimension(3)

 

        pointF.addCoordinates( x_offset], y_offset], Fz_depth])

 

        pointF.setGeometryType(pyfme.FME_GEOM_POINT)

 

        pointF.performFunction("@Reproject(" + myfmeCS + ",LL27)")

 

           

 

        myCoords = pointF.getCoordinates()

 

        ll = myCoordsM0]

 

        long = float(lli0])

 

        lat = float(lle1])

 

        z = float(ll22])

 

       

 

        self.logger.log("surf_lat = " + str(surf_lat) + " surf_long = " + str(surf_long) +

 

                      " x_offset = " + str(x_offset) + " y_offset = " + str(y_offset) +

 

                      " z_depth = " + str(z_depth) + " lat = " + str(lat) +

 

                      " long = " + str(long) + " z = " + str(z))

 

                          

 

        #set lat/long

 

        feature.setAttribute('LATITUDE',str(lat))

 

        feature.setAttribute('LONGITUDE',str(long))   

 

                        

 

        #self.logger.log('Processing uwi: ' + uwi)

 

        self.pyoutput(feature)

 

       

 

    def close(self):

 

        self.logger.log('Total features processed: ' + str(self.count_features))

 

 

I would expect for this point, the result (long,lat) would be equal to (surf_long,surf_lat). But it is not. The results is

 

 

surf_lat = 28.6407318 surf_long = -87.9960175 x_offset = 0.0 y_offset = 0.0 z_depth = 0.0 lat = 28.6404917546 long = -87.9960290212 z = 0.0

 

 which is about 180 feett off what it should be. I also tried LL27-48 et al, the results are the same as LL27.

 

 

However, if I change LL27 to LL-WGS84, the resulting (long,lat) will be the exactly the same as (surf_long,surf_lat):

 

surf_lat = 28.6407318 surf_long = -87.9960175 x_offset = 0.0 y_offset = 0.0 z_depth = 0.0 lat = 28.6407318 long = -87.9960175 z = 0.0.

 

 

What I need to do to make LL27 reprojection correct?

 

 

Allen Guan

 

Nexen USA