[mkgmap-dev] [Patch] improve handling of only-restrictions with via ways

Thu Oct 10 10:49:32 BST 2019

Hi all, 

in http://gis.19327.n8.nabble.com/Turn-Restrictions-using-three-ways-design-guide-for-OSM-mappers-tp5949183.html
Thanks to blc I've learned that only_* restrictions with via ways should be interpreted a bit different. As you might know the Garmin IMG format only has restrictions of type "no", so mkgmap has to translate "only" restrictions to a list of "no" restrictions. For those "only" restrictions the current code in version r4295 checks the roads connected to  (the last) "via"-node and adds a "no" restriction for all ways except the "to"-way. 
The meaning of an "only" restriction with "via"-way(s) is a bit different . I means something like "once you have reached the node that connects the "from"-way with the (first) "via"-way travelling on the "from" way you MUST use the route described in the restriction relation unless you have reached the "to" way.
So, mkgmap must add restrictions for each route node on the "via"-way(s), not only the last.

The patch implements this and no longer prints a warning for "only"-restrictions with "via" ways (severity was changed from warning to information).

I've uploaded a binary here:
 http://files.mkgmap.org.uk/download/452/mkgmap.jar

If I hear no complains I'll commit this patch next Monday.

Gerd
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