KML to GeoJSON to TopoJSON on Mac OS X

These introductions help you to convert a KML file to TopoJSON which allows you to reduce filesize.

Converting KML to TopoJSON

# Get KML (File -> Download -> KML)
https://www.google.com/fusiontables/DataSource?docid=153JjwSASwB6C4r1o0itwZr7imkDfuedEGIjk4LHr#map:id=3

# Install node via ports or brew (if not yet available)
port install npm
brew install node.js

# Install togeojson (might need admin privilidges)
npm install -g togeojson

# Rename file to data.kml
cd Downloads
mv Kuntarajat\ 2015.kml data.kml

# Convert KML to GeoJson with togeojson
togeojson data.kml > data.json

# Install topojson (might need admin privilidges)
npm install -g topojson

# Convert GeoJson to TopoJson
topojson data.json -o data.tjson -p Name

# Simplify if needed
topojson data.json -o data.tjson --simplify-proportion=0.5 -p Name

# Use tools to determinate appropriate simplify value
http://www.mapshaper.org/
http://shancarter.github.io/distillery/

---

Implementation guidelines

# Get TopoJSON library
https://github.com/mbostock/topojson

# In your implementation define a map
var map = new google.maps.Map($('.map_container')[0], {
    center:new google.maps.LatLng(60.25, 24.87),
    mapTypeControl:false,
    mapTypeId:google.maps.MapTypeId.ROADMAP,
    minZoom:9,
    overviewMapControl:true,
    panControl:true,
    scaleControl:false,
    streetViewControl:false,
    zoom:yleApp.zoom,
    styles:styler,
    zoomControl:true
});

# Attach polygons to the map
$.getJSON('data.tjson', function (data) {
    yleApp.map.data.addGeoJson(topojson.feature(data, data.objects.data));
});

# Define polygon styles
yleApp.map.data.setStyle(function (feature) {
  return {
    cursor:'pointer',
    fillColor:'#f00',
    fillOpacity:0.6,
    strokeColor:'#666',
    strokeWeight:0.5
  }
});

# Attach listeners
map.data.addListener('mouseover', function (event) {
  yleApp.map.data.overrideStyle(event.feature, {
    fillOpacity:0.8,
    strokeWeight:1
  });
});

map.data.addListener('mouseout', function (event) {
  map.data.revertStyle();
});