[mkgmap-dev] Commit: r1893: Add option to control the smallest polygon that is displayed

Thu Mar 10 17:19:55 GMT 2011

On 10.03.2011 18:09, Johann Gail wrote:
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>> Why did you change the merge-lines text at the same time?
>>
>> --merge-lines
>>     Try to merge lines. This helps the simplify filter to straighten out
>>     longer chunks at lower zoom levels. Decreases file size more.
>>     Increases paint speed at low zoom levels.
>> *At the moment this option causes routing errors. Use only if routing
>>     is not needed in your map.*
>>
>> Where is any reference to this causing routing errors. Routing is 
>> only on res=24, though merge-lines now by default starts at res=22 
>> (and even before ran after routing - which causes display panning 
>> problems and maybe label problems, but no changes on routing as such. 
>> Also the max error is now much smaller (1/4) compared with the old 
>> behaviour).
>>
> This text was added in my patch as a side note while editing the help 
> file. I have never watched routing errors for myself, but the internal 
> data structures gets corrupted. AFAIR there was a problem with the 
> drawing of the pink line. The routing layer should be intact, but some 
> internal references at the lower resolutions are wrong.
> If the maps work for you even with routing, then well, its okay, use 
> it and enjoy.  But I expect strongly some side effects, so I added 
> this warning. It is simply a warning, not more and not less.
Well on my tries routing stayed 1:1. Only the tooltip is showing up at 
wrong places on the map - and once you drag/pan the map, the engine 
thinks you panned it from the wrongly showing place, leading to a big 
jump. This error gets smaller by 50% on each resolution down. Therefore 
it only really matters for resolution 23 and 24, and the reason for the 
change a few revisions back, was to get the worst noticeable problems away.

There are options that cause far more problems like --ignore-osm-bounds 
or not using remove-short-arcs (this should be default when --route is 
given because if not used routing really gets broken for any highway 
that has segments shorter than 2.8m),or --link-pois-to-ways which makes 
gps crash on search and one map using it destroys search for all other 
maps on many GPS units.
Also lower-case which is known to cause loads of errors (without any 
indication of it working). While transparent and show-profiles may be 
problematic if you don't understand exactly what they do.

Close-gaps and floodblocker should be default if sea is generated (would 
save lots of people complaining about sea overflowing while the problem 
is in OSM data).
>
> Regards,
> Johann
>