-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Steve Hill wrote: | On Thu, 8 May 2008, Robin Paulson wrote: | |> alternatively, are there any world wide maps out there with contours |> and osm data, that update regularly? | | The cycle map and the piste map both have contours for selected areas. | I'm generally doing monthly updates to the piste map data. As far as I | know, no one is serving contours for the whole planet - there are a couple | of reasons: | | 1. The SRTM3 dataset for the whole planet is pretty huge once it has been | processed into contour lines and put into PostGIS (probably about half a | terabyte). | 2. It isn't as simple as just rendering the same contour lines everywhere | - for example, the piste map uses much wider spaced contour lines than the | cycle map because the terrain is (generally) more mountainous. To make a | global contour map you would need to make the renderer vary the number of | contour lines used depending on how mountainous the terrain is.
Why not draw contours in a light shade, then draw every 10th contour line in a darker shade. On a mountain, the light shades may just blend into the terrain of the mountain, leaving the dark lines picking out the ~ contours of mountain itself. If neccesary, you could have several levels of colour for different powers of 10. What would be nice is to separate the map into a background layer, with areas, and a transparent foreground layer with the roads, so that a contour layer can be slipped between the two at the openLayers level. Robert (Jamie) Munro -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFIJYuez+aYVHdncI0RAivMAKC95QGcxp7jbtwe+kMBZN+u/KNU3gCfVvKv Rf80HPgAHgwMVEpUMdMIhzY= =Fugf -----END PGP SIGNATURE----- _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/cgi-bin/mailman/listinfo/talk