[mkgmap-dev] Testing inter-tile routing with mapsource

Fri Feb 20 16:46:56 GMT 2009

Hi Paul,

> Using maps generated with r915 I've spent a while trying to route to
> places all over the UK. Places within my start tile work fine as expected.
> 
> Inter-tile routing works but I have the following observation
> 
> If you route to somewhere just inside the adjacent tile then the route
> selected is usually fine. If you route to somewhere deep inside the
> adjacent tile then the route chosen is far from optimal. It's as though
> motorways are being avoided until you are out of your starting tile
> after which the route takes the shortest path to a motorway and proceeds
> as expected. This seems to happen if travelling North, South or East
> (I'm not in a position to test West)
> 
> Similarly routing to places beyond adjacent tiles is not optimal but
> presumably this is due to the above e.g. going from Manchester to
> Taunton doesn't hit the M6 until near Stoke. After that it leaves the M5
> north of Bristol, goes through the middle of Bristol and then rejoins
> the M5 but this is near the NW corner of one tile and the SW corner of
> another so I would expect oddities at this point.
> 
> The work that's been done so far on inter-tile routing is fantastic and
> I don't want anyone to think I'm having a go I just thought the info
> would be useful

Not for one moment, do I think you're "having a go" - the feedback is
really useful to have.

Here's a thought off the top of my head. For optimal routing over long distances,
could the map also contain tiles that cover a larger area but with less detail?
Steve, Robert any thoughts on that idea?

Cheers,

Mark