Vishful thinking…

Tiling Vector Data for VirtualEarth applications

Posted in Uncategorized by viswaug on January 21, 2008

What does tiling vector data even mean? Well, I have wondered about the capabilities of the browser and the DOM to handle large vector datasets when they are uploaded to VirtualEarth. Infact, the Shape2VE project that I had undertaken was a direct result of that curiosity. When developing the Shape2VE application, I soon came to realize that once you exceed adding 300-400 shapes on to VirtualEarth, the performance starts degrading really fast and soon the application becomes unusable. Also, when adding large amounts of data to map, the browser stays unresponsive. Thus, I had to write Shape2VE so as to load the data asynchronously.

So, I was glad to know that Microsoft Research (the team that brought you MapCruncher) is striving to solve that same problem. They have released a TiledVectorsDemo application that attempts to solve this problem. They are utilizing a Python script to create tiles for the vector data which is in a GPX format. The Python offline preprocessor script works on the GPX data file which is about 2.5MB is size and chops it up into tiles and stored just like raster tiles. Unlike, raster tiles, the vector tiles are stored as JavaScript files containing first-class Javascript objects. The VirtualEarth application loads up only the tiles that are in the visible map area. And as the tiles go out of the visible extent of the map, they are deleted from VirtualEarth. Individual vector tiles are added to VirtualEarth as different layers. Since, the vector data is stored in vector tile files, they can be cached on the client so that they can be loaded faster if needed later. Pretty nifty I would say…

Can’t yet comment on the viability of this kind of technology for larger datasets, but it would be great to see this kind of technology be integrated with other technologies like GoogleGears and leverage its client-side database capabilities. But it certainly seems like a positive step in the right direction. I am kind of bummed that the script extracting vector tiles from GPX files is in Python and not in .NET…

Here is the TiledVectorsDemo.

And here is more information regarding the project.

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3 Responses

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  1. [...] Well Known Vs. Rational Vector Delivery – Part 3 It looks like the boys at Microsoft Research implemented my idea: tiled vectors.  Their demo makes on thing obvious, however.  Douglas-Peucker just doesn’t cut it for topologies.  This becomes a non-issue with a pixel-level of detail, but just looks bad in their demo.  Their implementation doesn’t seem to preserve existing points between zooms; its probably just as efficient this way.  Via Vish. [...]

  2. Tiled Vectors in Virtual Earth said, on February 1, 2008 at 10:39 pm

    [...] data set with 50,000 segments in it you really start to see why this is impressive. Vish has even more thoughts on the [...]

  3. Nishant said, on July 1, 2010 at 1:00 pm

    Hi

    Can anyone have any idea of vector tiling using Python.

    Please let me know the name of commad of python and python version alsoooo…it’s urgent

    Kind Regards
    nishant


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