Google Elevation API wrong path parameter

Question

I'm using google elevation service

I want to fetch data for my path, which consists of about 1k points. I know that I cannot sent them all in query divided by | separator, because I would exceed request size limit, so I'm encoding those points as it is mentioned in docs by Encoded Polyline Algorithm and send them like:

https://maps.googleapis.com/maps/api/elevation/json?key=KEY&path=cgg%7EE%7C%7B%7EpUfcaAwe%7CG&samples=3

Points: 36.578581,-118.291994|36.23998,-116.83171

Points encoded: cgg~E|{~pUfcaAwe|G

Points encoded + urlencoded: cgg%7EE%7C%7B%7EpUfcaAwe%7CG

But I'm getting the following error message:

Invalid request. Invalid 'path' parameter..

When I ask google with non encoded query (path separated by pipe separator) I receive proper data.

Do you have some hints what I am doing wrong in here?

Answer 1

The path parameter expects your encoded points to be prefixed with enc:

This is not super clear from the documentation, I must admit.

With your encoded points cgg~E|{~pUfcaAwe|G the path parameter would become:

path=enc:cgg~E|{~pUfcaAwe|G

Proof of concept:

https://maps.googleapis.com/maps/api/elevation/json?key=YOUR_API_KEY&path=enc:cgg~E|{~pUfcaAwe|G&samples=3

You must replace YOUR_API_KEY with your own key.

This returns the following:

{
   "results" : [
      {
         "elevation" : 4411.8828125,
         "location" : {
            "lat" : 36.57858,
            "lng" : -118.29199
         },
         "resolution" : 19.08790397644043
      },
      {
         "elevation" : 1372.885498046875,
         "location" : {
            "lat" : 36.41150237848279,
            "lng" : -117.5602587614725
         },
         "resolution" : 9.543951988220215
      },
      {
         "elevation" : -84.51690673828125,
         "location" : {
            "lat" : 36.23998,
            "lng" : -116.83171
         },
         "resolution" : 9.543951988220215
      }
   ],
   "status" : "OK"
}