Klokan Technologies GmbH

Custom style for Google Maps

klokan@klokan.cz (Klokan Petr Přidal) — Fri, 21 May 2010 09:24:00 +0000

I am impressed by the new functionality in Google Maps API V3: StyledMaps

You can create your own dynamic style for Google Maps tiles - and change the look and feel of the base maps which you want to include in your website.

It is quite a natural step, something what open-source projects like Cascadenik and products of other companies such as CloudMade made possible already some time ago. The adoption of this functionality by Google brings this possibility to masses.

If you want to define your own styles for the map you can use the online Style Map Wizard tool. More info and the official announcement is available here.

Tiles à la Google Maps: Coordinates, Tile Bounds and Projection...

klokan@klokan.cz (Klokan Petr Přidal) — Thu, 27 Nov 2008 07:41:00 +0000

I prepared an online tool I was missing when I started to study how the tiling using Spherical Mercator runs in Google Maps, Virtual Earth, Yahoo Maps, OpenStreeMap and others... This tool can help you to understand how are the tiles referenced and how they are stitched together in the browser.

I think this mashup could be an excellent starting point for people who are interested in this subject, because it contains all the math what you need for overlaying your own geodata from external sources: it can be tiles pre-generated by Maptiler/GDAL2Tiles following the OSGeo TMS recommendations, it can be raster data from WMS servers probably cached by TileCache, or tiles from MSR MapCruncher etc.

The tool is excellent for fast debugging of tiling for particular area, because you can use the search for display the tiles of a given place.

A transparent tile with correct coordinates is displayed for every original map tile by calling Google Chart API service.
Whereever you click the longitude/latitude boundaries of the underlaying tile are displayed in WGS84 datum. Boundaries are also displayed in projected Mercator coordinates (EPSG:900913, EPSG:3785) and in pixels for active zoom level. This information is all you need for generating custom map tiles.

The site contains also a Python script doing the coordinates and bounds calculation offline.

So enjoy this mashup:

Tiles à la Google Maps: Coordinates, Tile Bounds and Projection

BTW This demo is part of the documentation of MapTiler application.

Opacity Control for Google Maps in official demo gallery

klokan@klokan.cz (Klokan Petr Přidal) — Mon, 03 Nov 2008 08:21:00 +0000

One of the results of the MapTiler/GDAL2Tiles is an extension of Google Maps API for new functionality related to tile overlays. In summer I created an Opacity slider control for Google Maps which lets the user drag a slider to change the transparency of a TileLayerOverlay on the map.

Recently I was contacted by Pamela Fox from Google and now she add my control to the official Google Maps API Demo Gallery.

I still should add similar control to OpenLayers, but till now there was no time for that unfortunately. The design of the control is finished (done in SVG in Inkscape, same as the Google one), so only the coding in JavaScript is missing. Christopher Schmidt from OpenLayers recommended to create a new OpenLayers Addin.

Google IP Geolocation

klokan@klokan.cz (Klokan Petr Přidal) — Tue, 26 Aug 2008 16:20:00 +0000

Google just published new AJAX API function ClientLocation for IP Geolocation.

This way you receive an JavaScript object with latitude and longitude and with address (city, region, country and country code) of your visitor.

It is cool and practical for use even without displaying Google Maps, as you can change behavior of your website according location of the visitor.

I wrote a typical example application Google IP Geolocation Map and Address which you can just copy and paste.

What IP database is Google practically using? Anybody knows? Is it their private or they are licensing one from another company?

Is the quality of IP geolocation better then free GeoLite City from MaxMind?