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Large shapefiles on small screens using a drawable spatial index

Sometimes a large vector layer needs to be rendered on a relatively small area on the screen. This happens especially with mobile devices, where screen size ranges between 240 x 320 and 480 x 850 pixels. If the vector layer affects a small number of pixels, it makes no sense to go through all the … Continue reading

Tile pyramids versus TIFF, ECW and such on mobile devices

Due to poor performance and portability issues associated with raster libraries, I don’t think it’s a good idea to use raster formats such as TIFF, ECW or MrSID on mobile devices such as (smart)phones, pocket PCs, tablets, etc. Google Maps, OpenLayers and OpenStreetMap have made quadtree tiles very popular. Initially intended to increase web mapping … Continue reading

Doing nasty things with Spherical Mercator tiles: Ordnance Survey 1857 map versus OpenStreetMap

Since tiles from different sources are being stored in the application cache with a common namespace, you can move tiles from one folder to another to get funny, revealing combinations: And here is a nice screenshot in full-screen mode (click to expand):