Making Maps Navigable - Programming GPS and OpenStreetMap Applications with Java - page 108

ˆ reduce highway file to leave only motorway.highway tags;

ˆ reduce railway file . . . .

The goal is to balance the reduction of map data with, for example, the
rendering in Kosmos to get a smooth performance (and space) distribution.
Since the aim of the GER project is a full country map, all details on the
city level can be reduced by building related attributes, etc.
In the product-definition phase, an interactive tool like JOSM can also
help a lot: The 30 MB file germany.highways.osm can be opened with JOSM,
< CTRL >< A > selects all the map data and all attributes are shown. By
clicking an attribute line and < DEL > the attributes are removed from the
visible map. On the other hand, this takes longer than parsing it and the
resulting file is actually growing, so it should be -clean ed afterward.
At this point of the topic, we no longer will be processing really big les.
Now, the product designers can interactively process the smaller files and
combine them as needed. With only a few minutes of processing time, an
open file explorer, command line, and text editor, this phase can become
addictive.
Using the material covered in the preceding sections, the reader can
build his own Germany image with Kosmos. The directories

../resources/OSM.compiler/products/GER/carto/pix
../resources/gps/GER

provide some sample pictures and the GERcarto.bat lists how to create an
image via command line|after having set up Kosmos interactively.
While the drawing of the background (the big files) is left to the reader,
the other files have been crunched, cleaned, visually checked, and manually
modified to finally extract three networks with a number of cities.

admin 121,034 cities.osm

networks 32,316 highways.osm

38,879 railways.osm
27,066 waterways.osm

A look at the network files in JOSM reveals the simplicity of the net-
works. In the process of prototyping, it is helpful to have a look at some
nodes. For a real-world application, it would be worth the work to stick to
the original geometry of the networks and inject an additional tag

<tag k="roaf" v="Navigator"/>

to the online OSM map to provide a public roaf map. Then, the network
would closely match the real world, and the real objects could be localized
on any map, and the compilation process could be greatly simplified.