ST_AsEncodedPolyline — Returns an Encoded Polyline from a LineString geometry.
text ST_AsEncodedPolyline(
geometry geom, integer precision=5)
;
Returns the geometry as an Encoded Polyline. This format is used by Google Maps with precision=5 and by Open Source Routing Machine with precision=5 and 6.
Opzionale precision
specifica quante cifre decimali saranno conservate nella polilinea codificata. Il valore deve essere lo stesso nella codifica e nella decodifica, altrimenti le coordinate non saranno corrette.
Disponibilità: 2.2.0
Di base
SELECT ST_AsEncodedPolyline(GeomFromEWKT('SRID=4326;LINESTRING(-120.2 38.5,-120.95 40.7,-126.453 43.252)')); --result-- |_p~iF~ps|U_ulLnnqC_mqNvxq`@
Use in conjunction with geography linestring and geography segmentize, and put on google maps
-- the SQL for Boston to San Francisco, segments every 100 KM SELECT ST_AsEncodedPolyline( ST_Segmentize( ST_GeogFromText('LINESTRING(-71.0519 42.4935,-122.4483 37.64)'), 100000)::geometry) As encodedFlightPath;
javascript will look something like this where $ variable you replace with query result
<script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?libraries=geometry" ></script> <script type="text/javascript"> flightPath = new google.maps.Polyline({ path: google.maps.geometry.encoding.decodePath("$encodedFlightPath"), map: map, strokeColor: '#0000CC', strokeOpacity: 1.0, strokeWeight: 4 }); </script>