I'm interested in reading the paper, especially if it describes the data format you guys are using. It'd also be cool if your website had a running example so those of us without iPhones, etc can check it out. There are a few libs that do geometry clipping very well, especially for complicated area polygons such as coast line data, that are available freely. I might have actually done something similar (generated tiled vectors for osm's coastline) for an offline application and I'm interested to see your process/methodology.
Preet On Fri, May 25, 2012 at 9:07 AM, Tom MacWright <[email protected]> wrote: > 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 <[email protected]> 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 >> _______________________________________________ >> dev mailing list >> [email protected] >> http://lists.openstreetmap.org/listinfo/dev >> > > > _______________________________________________ > dev mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/dev > _______________________________________________ dev mailing list [email protected] http://lists.openstreetmap.org/listinfo/dev
