Hi everybody, on Saturday during the Code Sprint of the FOSS4G 2009 conference in Sydney we have made quite interesting step forward in the web cartography. With the help of other open-source developers I put together a prototype of the client-side map reprojection implemented only in JavaScript (using HTML5 Canvas tag and the Proj4js JavaScript library).
An image as JPEG, PNG or GIF is with JavaScript in a web-browser warped into a different map projection. The example is reprojecting the world image into the Spherical Mercator (map projection of Google Maps), into the map projection used in US National Atlas, into Canada LCC and into the Mollweide projection (used by National Geographic for thematic mapping). To try it you need any web browser which supports HTML5, it means the latest version of Firefox, Chrome, Safari or Opera. Have a look at the demo: http://examples.maptiler.org/map-reprojection-html5-canvas/ It is just a prove of concept in this moment, but I am sure practical applications will follow. The most typical use could be the client-side warping of raster data (weather forecast, ..) into the correct image overlay of Google Maps and similar online maps. Any WMS sever providing only EPSG:4326 can now correctly overlay Google Maps, if somebody use this technique to prepare the mash-up. Of course the speed can be an issue in this moment, but there is plenty of space for improvement in the warping code, and it can be done in a separate computing thread, which is possible with HTML5 Web Workers... Best, Klokan Petr Pridal -- http://blog.klokan.cz/ http://www.maptiler.org/ http://www.oldmapsonline.org/ _______________________________________________ Dev mailing list Dev@openlayers.org http://openlayers.org/mailman/listinfo/dev
