[mkgmap-dev] Configurable flood blocker

Fri Dec 17 15:49:16 GMT 2010


On 17.12.2010 16:45, WanMil wrote:
>>> Thanks Felix,
>>> I tested it now with:
>>> extend-sea-sectors,close-gaps=6000,floodblocker,fbgap=60,fbthres=200,fbratio=0.6,land-tag=natural=background 
>>>
>>>
>>> No errors and sea polygons came back, but the floodblocker blocks 
>>> still too much.
>>> I've tried it with other fb numbers but it still gives the same 
>>> picture:
>>>
>>> http://img404.imageshack.us/img404/3702/nogroningen.jpg
>>>
>>> The tested tile you can download at 
>>> http://mijndev.openstreetmap.nl/~ligfietser/diverse/Test.zip
>>
>> Minko,
>>
>> I will download your test data and give it a try.
>>
>> If you want to get detailed information what the flood blocker is doing,
>> you should enable an appropriate logging.
>> See
>> http://www.mail-archive.com/mkgmap-dev@lists.mkgmap.org.uk/msg02381.html
>> how the logging.properties file can be configured and add the line
>> uk.me.parabola.mkgmap.reader.osm.SeaPolygonRelation.level=INFO
>> to the logging.properties file.
>>
>> You might also add the parameter fbdebug to the sea-generation options.
>> In this case the flood blocker creates GPX files for each checked
>> polygon and the pro blocking (highways) and the contra blocking (ferry
>> routes) points. Opening these files with JOSM makes it easier to
>> understand why the flood blocker fails.
>>
>> WanMil
>
> Ok, I have tested the tile with your parameters.
> The sea generator created one big sea polygon (sea_polygon.png). As 
> you can see the polygon is erroneous because it intersects itself. 
> This is caused by the incomplete coast data in the tile which squeezes 
> the sea generator to guess how the real sea polygon looks like.
> I must admit that a check could be added if the polygon intersects 
> itself and in this case the sea sector extension could try some other 
> completion strategies. (But that's not a task of the flood blocker and 
> I guess it would be a performance problem.)
>
> Without the flood blocker large areas near the german border would be 
> flooded. The flood blocker detects that (see sea_polygon_contra.png) 
> by checking how many blocking points are contained in the polygon. In 
> this case there were 26602 points within the sea polygon and therefore 
> the polygon was converted from sea to land polygon. As a result the 
> flood blocker worked perfectly!
>
> You can see the result of the flood blocker in the logfile:
> Flood blocker for sea polygon 4611686018427390756
> area 476449303,0000
> sea 125
> land 26602
> ratio 5,5571
> Polygon 4611686018427390756 type sea seems to be wrong. Changing it to 
> land
>
> So from my point of view this was a good test case for the flood 
> blocker and it worked as expected.
>
> Have fun!
> WanMil
Well can you check why it does not work when giving "polygons" or 
"no-mp" as command? Multipolygon mode is not really the best solution....