[mkgmap-dev] Unusual Routing Behaviour in BaseCamp

Fri Nov 13 10:05:00 GMT 2020

Hi Dave,

if I got that right this part of the map is in Zambia, so without bounds you have to tell mkgmap that it is a drive-on-left country, else you'll get completely wrong results. Besides that Basecamp often doesn't find the shortest route in car mode.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Dave <dfjkman at gmail.com>
Gesendet: Mittwoch, 11. November 2020 09:22
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: [mkgmap-dev] Unusual Routing Behaviour in BaseCamp

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