Hi Steve, thanks a lot for the detailed answer.
Garmin seems to split it's map by equal areas, feature density and country border. The last is pretty nice, but I can understand if it's not of much interest for OSM, as your maps don't have to stop at the country borders for commercial reasons. For the overlapping maps have a look: http://www.qlandkarte.org/shot8.png I just selected my favorite spot by a single click. Think that is very confusing for most users. Oliver > Hi > >> * The basemap is really bad. Isn't there a possibility to draw at least >> country borders and major highways? > > Yes the basemap is a problem as it is empty apart from the required > definition areas. In fact an earlier version of mkgmap did include major > highways and coastlines, but this was lost when combining pre-existing .img > file was added. I need to bring it back, I will probably do this fairly > soon as I was thinking about it recently. > >> * Tile size. Why so many small tiles? That is one part of the mess in >> the basemap. And it's a real performance hit to render. I really > > You can certainly create large files with mkgmap. There are two problems > for Carsten's maps. The first is that they are constructed by dividing the > world into equal-sized chunks, and so that size is determined by the most > dense area. We really need something that splits the map based on the > number of features in an area. > > Second is that the default style is quite heavy weight and includes for > example residential streets on two different levels. This will make tiles > in city areas about twice as large as they would be on other maps. > > But this is all configurable and as it is now possible to have several > different built-in styles, it would be very valuable to have one that is > good for making maps of large areas that had fewer levels. > >> * Spend more zoom levels in the basemap. Only one is sparse and for the >> outer zoom levels the basemap is enough. Right now I have to parse a >> huge amount of files for outer zoom levels. Look, these are the zoom >> levels for City Navigator Europe V8: > > This is entirely configurable by the map maker. The option levels="0:23, > 1:21, 2:19" > would give the same as the City Navigator map example you gave apart > from the overview map. > >> * Another huge performance hit are staircase lines in the outer zoom >> levels. I have to re-project every polyline point. That is expensive. If >> the highway does not change the average direction it can be interpolated >> by a line. No one expects GPS accuracy on that level. It's just for >> overview. > > There is some simplification of lines and it is not very good. However > the OSM data tends to split roads into many small pieces and I think that > to simplify things properly you would have to join them together or at > least know where the next segment was going. That's is a fairly big change > but I will keep it in mind. > >> * Also highways seem to have all their ramps up to the outer zoom >> levels. That does not add any information. But eats up resources. > > If the ramps were tagged differently in OSM then they could be left out > at higher zoom levels, but as for trying to recognise them I don't really > know how I would do that. Its an extension of the previous problem in that > case. > >> * Every minor water body seems to be drawn in the outer zoom levels. >> That does not add information either. Big lakes and major streams are >> enough. > > Yes this is a good point. I had forgotten about selecting features for size. > I will think up a way of specifying this in the style. > >> * Tiles must not overlap. Tile selection is really bad if they do. > > If the input OSM files do not overlap and they contain a <bounds> element > then the tiles should not overlap. I though Carsten's maps did that though. > The usage of the map-coverage-area element is somewhat broken - that may also > cause problems. > > ..Steve > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's challenge > Build the coolest Linux based applications with Moblin SDK & win great prizes > Grand prize is a trip for two to an Open Source event anywhere in the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > QLandkarte-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/qlandkarte-users -- -------------------------------------------------------------------- DSP Solutions GmbH & Co. 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