I'm currently working with OS data and have just tried to import a table of google maps coordinates/point data into ARC. The data frame (& layer) coordinate system is as follows:
British_National_Grid
WKID: 27700 Authority: EPSG
Projection: Transverse_Mercator
False_Easting: 400000.0
False_Northing: -100000.0
Central_Meridian: -2.0
Scale_Factor: 0.9996012717
Latitude_Of_Origin: 49.0
Linear Unit: Meter (1.0)
Geographic Coordinate System: GCS_OSGB_1936
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_OSGB_1936
Spheroid: Airy_1830
Semimajor Axis: 6377563.396
Semiminor Axis: 6356256.909237285
Inverse Flattening: 299.3249646
I've imported the coordinates from google maps as a table, exported it as a shapefile defining the coordinate system to Spherical Mercator (ESPG 3857). I've then imported the data, transformed it to the above projection, in the hope that the two would align. The area of interest is London, and the points appear far further south than they should be – several lengths of the UK further south (but approximately at the right longitude).
Can anyone suggest what I might be doing wrong? I'm at a loss after having followed various online tutorials and how-tos. Sorry if this seems obvious – I'm a beginner.
Thanks –
Best Answer
For the points you gathered from google maps, you should use WGS1984:
GCS_WGS_1984 Authority: Custom
Angular Unit: Degree (0.0174532925199433) Prime Meridian: Greenwich (0.0) Datum: D_WGS_1984 Spheroid: WGS_1984 Semimajor Axis: 6378137.0 Semiminor Axis: 6356752.314245179 Inverse Flattening: 298.257223563