透過 Google Map API 取得高度

參考 Google Maps Elevation API

https://maps.googleapis.com/maps/api/elevation/json?locations=99.999,99.9999&key=xxxxx

{
   "results" : [
      {
         "elevation" : 123.7428283691406,
         "location" : {
            "lat" : 99.1729,
            "lng" : 999.6859
         },
         "resolution" : 152.7032318115234
      }
   ],
   "status" : "OK"
}