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matthewproctor / australianpostcodes

A community sourced comprehensive database of Australian Post Codes with geolocation data.
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Data fields for Google Lat/Lon #30

Open djireland opened 2 years ago

djireland commented 2 years ago

The data fields table mentions "Google Lat/Lon" but the corresponding fields in the (JSON) data don't use this convention.

Is locations from Google API denoted lat/lon_precise?

milkmanmatty commented 2 years ago

That's correct djireland, the google provided fields are called Long_precise, Lat_precise. However I would very careful fully trusting either set of coordinates them as in some cases they are actually inaccurate - even by Google's standards.

For example even just looking at Aus Capital Cities, Darwin 0800 has a Lat, Lon of -12.458684, 130.83668 which looks correct according to google maps. Going by the Long_precise, Lat_precise for the same entry gives a sightly different position of -12.3932794, 130.7766611 which ends up way in the water - this is clearly incorrect!

However the Lat, Lon aren't to be fully trusted either, the exact opposite problem happens for Sydney 2000. The Long_precise, Lat_precise give -33.8708464, 151.20733 which is correct while the normal Lat, Lon give -33.859953, 151.256649 which is in the middle of the water out in the bay. Similar story for Canberra.

So fair warning, I've recently been stung by this for various geo locations. Going forward I'll be averaging both sets of coordinates and using the midpoint. It's not great but I think it's the best try.