[mkgmap-dev] Optimizing MapSplitterFrom GerdP gpetermann_muenchen at hotmail.com on Wed Nov 12 17:39:58 GMT 2014
Hi Steve, Steve Ratcliffe wrote > As you've probably seen I've added the program to the display svn > as test.svg.subdiv.Main. There is an argument '--level N' to display > a different zoom level. Default is 0 (most detailed). > > I've found that our OSM maps seem to have a lot more elements than > other maps so it is difficult to compare. > In general the way we create subdivisions means that many of them > are quite large and they contain many elements. There are no > small divisions. Yes, I tried the tool on an OSM map and one from Garmin but the svg is so big and complex that it doesn't help me at this stage. Steve Ratcliffe wrote >> If I got it right, the redraw time is influenced by >> a) how many sub divisions are overlapping a given bbox and >> b) how many objects are in these sub divisions and >> c) how complex the objects are (means, how much time it takes to render >> them) > > It is also possible that the way that the divisions on different > levels link together may have an effect, as it may be able to > restrict the number of divisions it has to consider. Possible, I don't yet understand how this is used in the device as objects may (dis-)appear at a certain level. Anyhow, I am pretty sure that it doesn't take much time to find the areas which intersect a given rectangle. My first approach to solve the problem was to cut polygons and non-routable lines when a sub div is split, but that doesn't seem to help much (maybe the roads are the reason). Or maybe I did something wrong or looked at an area which doesn't show the problem. Now I wonder if we should collect objects with large bboxes in their own sub divs. A small sub div could be useful in heavily populated areas. I think I first have to code a test routine. Gerd -- View this message in context: http://gis.19327.n5.nabble.com/Optimizing-MapSplitter-tp5823702p5824117.html Sent from the Mkgmap Development mailing list archive at Nabble.com.
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