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Illustrate embedding geojson/topojson geometry into a google maps overlay using d3.geo.projection.

Based on which uses D3 to draw elements into a google maps overlay layer, but doesn't use d3.geo machinery to draw map geometry. This gist illustrates how to align a D3 mercator projection with google maps so we can do standard d3 mapping stuff on top of the google API.

<!DOCTYPE html>
<meta name="viewport" content="initial-scale=1.0, user-scalable=no"/>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script type="text/javascript" src=""></script>
<script src=""></script>
<style type="text/css">
html, body {
width: 100%;
height: 100%;
margin: 0;
padding: 0;
#map {
margin: 0;
padding: 0;
#d3map {
/*pointer-events: none;*/
-webkit-transform: none;
position: relative;
top: 0px;
left: 0px;
#countries path {
stroke-width: 1px;
vector-effect: non-scaling-stroke;
fill: none;
stroke: #333;
<script type="text/javascript">
var width = 600,
height = 400,
div ='body')
.style('width', width + 'px')
.style('height', height + 'px');
// Create the Google Map…
var map = new google.maps.Map(div.node(), {
zoom: 2,
center: new google.maps.LatLng(37.76487, -122.41948),
mapTypeId: google.maps.MapTypeId.TERRAIN,
minZoom: 2 // stuff goes wrong if we allow world wraparound
// Load the data. When the data comes back, create an overlay.
.defer(d3.json, "world-110m.json")
var svg, overlay;
function ready(error, world) {
var countries = topojson.feature(world, world.objects.countries).features,
land = topojson.feature(world,;
overlay = new google.maps.OverlayView();
overlay.onAdd = function() {
// create an SVG over top of it.
svg =
.style('width', width + 'px')
.style('height', height + 'px')
.attr('width', width)
.attr('height', height);
overlay.draw = redraw;
google.maps.event.addListener(map, 'bounds_changed', redraw);
google.maps.event.addListener(map, 'center_changed', redraw);
function redraw() {
var bounds = map.getBounds(),
ne = bounds.getNorthEast(),
sw = bounds.getSouthWest(),
projection = d3.geo.mercator()
path = d3.geo.path()
var p1 = projection([ne.lng(),]),
p2 = projection([sw.lng(),]);'#countries').attr('transform',
'translate('+(-p2[0])+','+(-p1[1])+') ');
svg.selectAll('path').attr('d', path);
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rlancer commented Jul 30, 2014

It doesn't pan right.

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I'm also noticing an issue with panning. The overlay layer moves at a different scale than the underlaying map, so it "floats" on top of it. Any idea what might fix this?

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