[mkgmap-dev] Turn restriction angle checks

Sun Mar 30 13:16:31 BST 2014

On Sun, Mar 30, 2014 at 02:05:08PM +0200, Gerd Petermann wrote:
>If I get that right the via way is a oneway going into the wrong 
>direction.

Oh, you are of course right. I will move the restriction to the proper 
ways.

>yes, I think mkgmap should try to detect unclear cases and ignore those 
>restrictions.

IMO, mkgmap should not silently ignore anything. We should generate a 
warning too.

BTW, one more case that I do not know if you are handling yet: Issue a 
warning if the result would not be any different if the turn restriction 
did not exist. This is not only about oneway direction. For example, if 
there is only_straight_on on a road with no junction, a warning should 
be issued.

BTW, I accidentally loaded a relation somewhere in Russia and downloaded 
the surroundings. There were lots of no_u_turn on every crossing of a 
major road. That kind of micro-mapping does not exist over here; I guess 
that mappers expect people to apply common sense and not make a u-turn 
as soon as the navigator suggests it, no matter what.

I think that no_u_turn restrictions are somewhat a matter of a local 
convention. In the US it is common to forbid left turns and U-turns 
except in a few junctions. In Finland, that practice only exists on some 
major through-routes in cities.

	Marko