[mkgmap-dev] [PATCH v1] add-pois-to-lines

Sun Oct 30 13:10:50 GMT 2011

> Moin,
>
> I tried the patch and I think the add-pois-to-lines option is quite usefull.
>
> Although I have some issues with the actual implementation.
>
> 1. Tags originating from the line are correctly transfered to the points (e.g.
> incline=* on the highway can be used to generate symbols at the highway nodes).
> But if the tags are originating from a relation and only generated on the way
> during the relation processing by the apply command, then this tags ar enot
> transfered to the points. So it is not possible to create POIs at all nodes
> belonging to ways belonging to a route.

The relation style is applied after the pois-to-lines. Maybe this could 
be changed but I don't know about side effects.

>
> 2. I think it should be possible to differentiate whether a single tag belongs
> really to this node or is create by the add-pois-to-lines processing. For
> example: We have a line highway=primary and this line contains a node marked
> with highway=trafic_signals. With the actual implementation the node would only
> have one highway-Tag, the other on gets lost. Perhaps it would be better, to not
> only transfer the tags from the line to the nodes, but add a prefix to the keys,
> e.g. mkgmap:line2poi:highway=primary

It is either possible to create completely new nodes (this is 
implemented) or to add the tags from the line to the existing nodes 
(then you get a "merge" problem if both line and node contains the same 
tag with different values). I decided to implement the first solution 
which is much easier.
You report that the information of original node is lost. I don't think 
so. But it is possible that somewhere else in the mkgmap code or in the 
Garmin software there is a limitation that there can be no more than one 
POI per coordinate. In this case the first (or last) POI created wins 
and the other is lost. This is not a problem of the pois-to-lines feature.

> 3. I think the tag mkgmap:line2poi=true  is not required, since all nodes are
> marked with mkgmap:line2poitype=* anyway.

That's true. I wanted to implement it similar to the add-pois-to-areas.

>
> 4. A single node can be member of multiple lines. E.g. a highway crossing can be
> the inner node of one line and also the start node of another line. Will this
> create any problems? With my suggestion 2 you could at least differentiate, when
> the line2poitype is different, but if the crossing is an inner node of two
> lines, you are still kind of lost.

You can invent serval extra mkgmap tags to solve this (e.g. 
mkgmap:line2poi:1:highway=secondary, mkgmap:line2poi:2:highway=tertiary 
for a crossroads of secondary and tertiary). But does that really help? 
And more important: Will anyone understand this in 2 months?
I don't think so.

WanMil

>
> Gruss
> Torsten
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