[mkgmap-dev] Unusual Routing Behaviour in BaseCamp

Wed Nov 11 08:22:40 GMT 2020

Hi All,

I have come across an unusual routing behaviour in BaseCamp on a stretch of
road in Lusaka. When using the driving profile with no avoidances selected
and the shorter distance route preference selected the route shown diverts
down a link road and is obviously not the shortest route. Changing the route
preference to faster time shows a more obvious route. Both route preferences
should, in my opinion,  be the same. See attached screen shots.

After some investigations it would appear that this occurs when the -bounds
option is used with bounds-latest.zip, if I do not use this option it routes
as expected.

The following are the commands used with mkgmap r4587:

Routing problem:

java.exe -jar C:\Users\Dave\Documents\Maps\Utils\mkgmap-r4587\mkgmap.jar `

                --output-dir='C:\Users\Dave\Documents\Maps\Temp\Output' `

                -c C:\Users\Dave\Documents\Maps\Options\Default.cfg `

                -c
C:\Users\Dave\Documents\Maps\Zambia\Split_Files\template.args `

The Default.cfg file has the following options:

country-name="Zambia"

area-name="Zambia"

country-abbr="ZMB"

overview-mapname=Zambia

product-id=1

family-id=2526

draw-priority=20

max-jobs                             

keep-going

tdbfile

order-by-decreasing-area

gmapsupp

bounds=C:\Users\Dave\Documents\Maps\Data\bounds-latest.zip

latin1

index

route

remove-ovm-work-files

nsis

By commenting out the bounds option I change the routing behaviour. I have
not used any typ or style files in case they were the cause of this. Also
not tried on my Garmin device yet to see if the same behaviour occurs there
as well. The routing error I have found occurs at this intersection but may
occur elsewhere https://www.openstreetmap.org/#map=19/-15.45547/28.26647. 

After some experimentation this only happens when the adjoining way is
tagged as a link road, in this case primary_link. Using JOSM I have changed
the tag to secondary and later primary, saved the file to my laptop then
processed the saved file and the unusual routing does not occur.

Regards,

Dave

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