How to decode Google's proprietary latLon format for China?

Question

This Google Maps link returns train stations in Shanghai, China. By appending '&output=js' it returns it in JSON format. I'm trying to decode the format Google uses for lat/lon:

latlng:{
    lat:0,
    lng:0,
    alt:{
        ll:"35122131713574191160",
        mode:2
    }
}

For all other countries, Google returns the lat lon values separated in the lat and lon . Only for China they return this strange ll value. Does anybody know how to decode it?

Answer 1

It isn't clear that the returned ll value encodes the latitude and longitude, it may just be some other piece of information they embed with the results. If it does encode the latitude and longitude, I'd go looking the way of geohashing and coordinate interleaving, both of which provide a conversion mechanism between single strings and a coordinate pair. If you're convinced that they are related, try gathering up a collection of values and try your hand at a linear solver or the like to deduce their relationship.