[mkgmap-dev] PATCH v1: highwayCount

Mon Feb 11 12:52:12 GMT 2013

Hi Gerd

> I don't understand all of your comments, but I think that either I

Yes, sorry, everything you were saying was fine, and I am confusing the 
issues by talking about other things. I will try to keep messages separate.

> missunderstand the code in
> RoadDef or something is wrong.

Yes, something is wrong.

Or more accurately: something is different to the way Garmin makes its
maps, but it (mostly?) works.

> The comment in RoadDef says
>   * A road definition.  This ties together all segments of a single road
>   * and provides street address information.

Yes, I still believe that this is how it is meant to work.

> but the current implementation works different.

Correct.

> In StyledConverter, we create one MapRoad instance for each segment of
> an OSM way. MapRoad itself creates one instance of RoadDef for this single
> segment.
> The RoadDef class contains code to handle multiple segments at the same zoom
> level.

Yes. But I think the only time that we get multiple segments is when a
line is split because it is too big for a subdivision.

> So, if my assumption is right that the order of segments does matter, we
> should probably make sure that the entries in NET1 appear in the right
> order,

- I don't think that the order of the entries in NET1 matters.

- The order of lines within a single NET1 entry may matter (but I don't
know for sure).

> or we should not create multiple RoadDef instances for a single OSM way.

We should probably join lines (like --merge-lines) and then prevent
subdivisions from growing too much. The problem is that we grow
subdivisions to fit lines so that there is a lot of overlap. The
alternative is to limit subdivisions so that they only overlap a
little and trim lines at their borders. It is similar to the same
problem with splitter.  Its hard to explain without a diagram, and I
would like a tool that shows the layout of the subdivisions so that I
can compare the strategy that we use compared to other maps.

..Steve