Monday, December 1, 2008

OpenStreetMap rendering in Silverlight part IV

A critical part of be able to show the maps is putting tiles together, today the code base solved a number of problems:
  • downloading data asynchronously (though not yet predicatively, or in parallel)
  • reduced data set transmission sizes (from 367mb to 97mb for the UK) - no compression yet.
  • clipping of drawing to fit within tiles, (applying higher level data to tiles does not draw outside the tile) though this does not yet crop the drawing effort (performance to be gained here)
  • multi-tile support, the code can handle multiple tiles independently (though does not yet know how to stitch properly yet).
All of this yields a nice improvement in speed and appearance, hopefully I can post a live version tomorrow.

The colours above are used to show which level the data existed at (per tile, cross tile etc) so you can see how the image is made of four tiles, with large entities (i.e. across tiles) being in different colours.

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