PostGIS
Description
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.
Optional precision specifies how many decimal places will be
preserved in Encoded Polyline. Value should be the same on encoding and
decoding, or coordinates will be incorrect.
Availability: 2.2.0
Examples
Basic
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>