[mkgmap-dev] [PATCH v2] heed the through_route relation when adjusting turn headings

Wed Feb 10 17:01:24 GMT 2010

Worked for me earlier today on a TOTSO that was previously missed.

Cheers

Paul

On 06/02/10 18:43, Mark Burton wrote:
> v2 - no longer requires the node to have role "junction"
>
> This patch also includes two other changes to the heading adjustment
> code:
>
>     When matching arcs, as a last resort, match road class and speed.
>     
>     If at a node, an outgoing arc cannot be matched to an incoming arc by
>     possiblySameRoad(), try to find a single outgoing arc that has the
>     same road class and speed as the incoming arc and use that.
>
> and:
>
>     When adjusting turn headings apply all relevant adjustments.
>     
>     Previously, if a heading needed adjusting because the delta from the
>     outgoing arc was too small, it did not then consider whether the delta
>     from the incoming arc was too small also. Now, it considers both cases
>     and adjusts the heading as appropriate.
>
> So please test even if you are not adding any through_route relations
> and if you see any notable changes (good or bad) please say.
>
> --------------------
>
> This new relation (type through_route) specifies which 2 ways are the
> "through route" at a junction. The relation requires 2 ways (no role
> required) and a node with role = junction. It should only be used at
> those junctions where the through route cannot be reliably inferred
> from the ways' names and/or refs.
>
> Here's an example from my local town:
>
>      |   1
>      |  /
>      | /
>      |/
>      A
>      |
>      |
>      |
>      |
>      B
>     /|
>    / |
>   /  |
>  2   |
>
> The vertical road is the "through route", i.e. you can drive from one
> end to the other without crossing any white lines. But, from point 1 to
> point 2 is a B road so ways 1-A, A-B, and B-2 all have some ref,
> say, B1234.
>
> Without the through_route relation, mkgmap assumes (erroneously)
> that the through route is 1-2 because all of the ways in that route
> have the ref B1234.
>
> By adding 2 through_route relations (one at A and the other at B),
> mkgmap is informed of the real through route and will take that into
> account when adjusting the turn headings. The end result is that the
> quality of the routing directions is improved (we hope).
>
> In this example, we need to have 2 relations because the B road
> joins/leaves the through route at two places. 
>
> So if you know of any junctions that would benefit from this relation,
> please add it to the map data and try this patch to see if it improves
> the routing instructions.
>
> Mark
>
>   
>
>
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev