How to Draw a Curved Great Circle line in Google Maps

Tuesday, April 22, 2008 at 11:12 am

Peter Rukavina

Someone came up to me in a coffee shop yesterday and told me they had a web application in which they wanted to connect two locations on a Google Map with a line. Not a regular straight line, but rather a curved “great circle” line. I mumbled about various possible approaches to this — setting up a custom tile-server and generating lines on the back end, etc. — only to find that this functionality is already build into the Google Maps API:

var polyOptions = {geodesic:true};
var polyline = new GPolyline([
  new GLatLng(61.1699849, -149.944496),
  new GLatLng(46.2361, -63.13)
  ], "#ff0000", 3, 1, polyOptions);
map.addOverlay(polyline);

Add an overlay like this — the key is the geodesic:true — and you go from straight line to curvy one. This is well-documented in the Google Maps API documentation.

GIS

Google Maps

Comments

If Google’s so geodesically

If Google’s so geodesically enlightened, why are they using that archaic projection that portrays Greenland as bigger than Africa?

Reply

You mean a “Mercator

You mean a "Mercator projection". It's not archaic. It's probably the most common type of projection used in cartography today, there are others of course, but anytime you put a 3D map on a 2D screen there must be some distortion somewhere.