[mkgmap-dev] BaseCamp_Route_Is_Reversing, GPS_Route_Is_Reversing

Sat Jun 5 10:31:25 BST 2021

Hi Eric,

I see these u-turns in maps which add multiple routable ways with different roadclass/speed for the same OSM way.
Another reason can be a parrallel cycle way.
The Garmin algo sometimes prefers to take the "better" road too long and go back on the "minor" road. 

The "avoid u-turn" option should help here.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von ankeric.osm at gmail.com <ankeric.osm at gmail.com>
Gesendet: Freitag, 4. Juni 2021 13:33
An: 'Development list for mkgmap'
Betreff: [mkgmap-dev] BaseCamp_Route_Is_Reversing, GPS_Route_Is_Reversing

Since a very long time (assumption: 2014, BaseCamp 4.3.3) BaseCamp routing will - sometimes - reverse, bites its own tail.

I have always assumed this is a Garmin BaseCamp error. It started with a specific BaseCamp version.

But it may have coincided with a mkgmap update ????

Garmin has always been assuming it’s mkgmap that is responsible for this.

Do these issues have any relation to mkgmap?

To avoid the error:

- Remove the viapoint after which the route is reversing (goes backwards).

- Put viapoint ON junction, not in the middle or beginning of a highway.

- Avoid putting a viapoint besides the highway.

To reproduce: try not to avoid, sometimes the error occurs.

Attached:

BaseCamp_Route_Is_Reversing.png

BaseCamp_Route_Is_Reversing.gpx

Route direction: from east to west.

East or arrow: route is correct.

West of arrow: route is reversing.

Map used for reproducing: OSM_MKGMAP_DEFAULT (But it’s reproduced on all maps (my own Bike_Map, OpenFietsMap, OSM_MKGMAP_GENERAL).

I've seen it happen on GPSMAP 66s as well.

Attached:

BaseCamp_Route_Is_Reversing_12307.bmp

Route navigation here comes from the south and should turn right (east) over the bridge.

But GPS indicates to go straight on and after 80 meters: turn round, reverse, U-turn.

No nodes close junction; highway south = unclassified, highway north and east = secondary

Eric (AnkEric)