[mkgmap-dev] merge-lines and routing

Sun Apr 28 21:20:42 BST 2013

Hi WanMil,

merge-lines happens for res < 22, see MapBuilder.java:
		if (mergeLines && res < 22) { 

My understanding is that routing is also done with the data of lower
resolutions, e.g. for long distance routing, but my patch below is probably
too simple, as it doesn't care about CoordNode. 
In StyledConverter a lot of code is used to split the way at the "right"
point.

Gerd

WanMil wrote
> Hi Gerd,
> 
> the merge-lines happens for resolution >= 22 only. AFAIK the routing 
> graph is based on resolution 24 only? So I would not expect a problem
> here?
> 
> Anyhow I am not sure. I started also some tests about routing (I did 
> have the idea expand the merge-lines filter to the routing graph). I saw 
> some roundabouts multiple times in the routing graph but I did not 
> analyze this in detail. I think I will have a look on in within the next 
> days...
> 
> WanMil
> 
>> Hi,
>>
>> the help file says
>> merge-lines
>> < ... >
>> 	At the moment this option causes routing errors. Use only if routing
>> 	is not needed in your map.
>>
>> Maybe I found the reason for the routing errors:
>> If the segments of a road are merged, it might happen that the
>> LineSplitterFilter has to split it because it has more than 250 points.
>> The current implementation of LineSplitterFilter does this:
>> The first part of a road is added as a road, all remaining parts are
>> added
>> as lines.
>> With a simple change all parts are added as roads:
>> Index: LineSplitterFilter.java
>> ===================================================================
>> --- LineSplitterFilter.java	(revision 2581)
>> +++ LineSplitterFilter.java	(working copy)
>> @@ -84,7 +84,7 @@
>>   					log.debug("saving next part");
>>   				l.setPoints(coords);
>>   				next.doFilter(l);
>> -				l = new MapLine(line);
>> +				l = line.copy();
>>
>>   				count = 0;
>>   				first = false;
>>
>>
>>
>> The interesting part for me is that the following routines seem to expect
>> exactly this, but parts of the code was never executed.
>> See also
>> http://gis.19327.n5.nabble.com/PATCH-v1-highwayCount-tp5748554p5748864.html
>>
>> I also wonder if it really makes sense to limit the check "Non-routable
>> way
>> with routable type ..." to resolution 24. I'll try to find out more
>> tomorrow.
>>
>> Gerd
>>
>>
>>
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