[OSM-dev] Some more notes on OSM vector-tiling

[Tom MacWright]

Hi Sandor,

Is any of this work open source, or have open specifications on the web?
Statements like comparisons between filesizes of raster & vector data need
to be cited.

Tom

On Fri, May 25, 2012 at 8:44 AM, Sandor Seres <sandors39 at gmail.com> wrote:

> Scale/zoom levels and tiling are essential for mapping servers, especially
> if pretending on streaming transmission model. In case of a
> vector/parametric data transmission service the scale levels’ generation
> and the tiling of these, as a rule, is performed in quite a different way
> compared to the traditional raster format based service (keep in mind that
> a well constructed vector format may 20 – 40 TIMES be smaller than the
> corresponding PNG raster format for the same content). We do an OSM vector
> transmission based service for mobile apps (see www.fasterimaging.com).
>
> As someone properly emphasized a clipping is essential for any vector
> tiling. But, while clipping of line-work objects (roads, streets, borders
> …) is rather trivial, clipping of area objects is somewhat more complex and
> complicated issue. Besides the clipping, some kind of area
> reconstruction/restructuring has to be done (one container area may be
> clipped into many parts, the same with the corresponding holes, the
> restructuring has to decide which new holes are in which new areas, than
> the issue of trivial tiles or empty tiles and tiles inside areas and so
> on). Also, tiling inevitably results in a considerably larger data amount
> compared to the original dataset. So, the question is – is it possible to
> provide a server that combines the tiling’s efficiency and the data size at
> certain, close to optimal, level. Fortunately, latest research and an
> experimental version of such a server show that the answer is yes. The
> experiments are performed on OSM vector data for Europe from some weeks ago
> (Roughly 30 object classes/layers, 12 area classes like rivers, lakes,
> forests, sea …, 12 line-work classes like roads, streets, paths, water
> lines … and some point object classes. POIs and LBSs are overlays on such a
> base map). The estimates also show that such a very simple server (no DB,
> no caching …) is fully realistic with extraordinary performance (respond to
> tens of thousands requests per second) and scalability (just make a new
> copy as needed).
>
> A  white paper, describing in more details the above subject, is
> available. Though in bullets format with many illustrations and with a
> working title – Hybrid data format, multi tiling and a new server model.
> Interested?
> Sandor
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>
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