[mkgmap-dev] The road network and duplicate ways

Sun Dec 1 07:29:40 GMT 2013

Hi Steve,

some styles assign create multiple routable lines for the same OSM way,
e.g. to set different road-class or speed values for bike and car.
This seems to work, but reg. performanc I see two points:
1) We do all kinds of calculations multiple times, e.g. all the bearing
calculations and (Douglas-Peucker) filters.
2) We save the points for the same line multiple times in the img file.

A possible alternative would be to have a class that stores
the list of points  and a list of assigned types, but that would involve
a lot of changes.
I wonder if the img format allows to store the points only once,
means, can we store one NET entry and multiple NOD entries
referring to the same NET entry?

Another point that I don't fully understand:
In RoadNetwork.addRoad() we always add the reverse arc for each 
arc. I wonder why oneway roads are not treated different here,
esp. if they have foot=no?

Gerd

P.S. A while ago I tried to find out the meaning of the curve data
encoded with two bytes. I failed because I was not able to change
display tool to read my Garmin map NOD file. I saw too many "sync lost" 
messages. I guess the format is too different, e.g. NOD header length is
0x3f.
I have created a local copy of NodConvert that is more up to date. Should
I commit that? 

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