Comment 6 for bug 1393111

Sooo .. I now see why its a difficult one to solve, you're literally working with a fast moving target. It seems the offsets vary depending on the world tile in scope of the current view.

I ported WorldLatLon.cs to golang to play with it easily on the command line.

 Using the Coals to Newcastle Route, I parked the camera under a known bridge in Taree - correct coords are -31.899305, 152.467734. WorldLatLon calculated it at -31.907621846997195, 152.44948874630478. So to try and line it up correctly, I changed the World Tile EW/NS offsets to double, and used precision to try and bump it closer to where it should be.

Incorrect:

ew_offset = -16385
ns_offset = 16385

go run main.go -ew=1564 -ns=10417 -x=-70.77898 -y=13.19096 -z=-548.0775
Goode World Tile X 17949
Goode World Tile Y 5968
Location on tile: -70.77898 -548.0775
Location on tile (cast): -70 -548
X coords 16742433
Y coords -3547964
GX / GY 1.6742433e+07 -3.547964e+06
Region 9
Radian - Latitude / Longitude -0.5568930577113754 2.660745521605061
Degrees - Latitude / Longitude -31.907621846997195 152.44948874630478

vs

Close to correct:

ew_offset = -16385.8929888
ns_offset = 16384.54879

go run main.go -ew=1564 -ns=10417 -x=-70.77898 -y=13.19096 -z=-548.0775
Goode World Tile X 17949.8929888
Goode World Tile Y 5967.548790000001
Location on tile: -70.77898 -548.0775
Location on tile (cast): -70 -548
X coords 16744262
Y coords -3547039
GX / GY 1.6744262e+07 -3.547039e+06
Region 9
Radian - Latitude / Longitude -0.5567478685047254 2.661064033661856
Degrees - Latitude / Longitude -31.899303118225294 152.46773814288318