[mkgmap-dev] routing between tiles

Thu Dec 11 09:51:29 GMT 2008

Hi,

I've done a small test with two tiles and a couple of boundary nodes  
(NOD 3). This by manual editing of .mp-files, so there may well have  
been errors on that side.

Results:

* Only one of the two tiles displays.
* Routing across tile boundaries works to some extent. It routes  
through the undisplayed tile, so the NET/NOD stuff is probably ok.

It seems like maybe a boundary node had better not be a junction:  
Routing seems to work better across those boundary nodes that were  
inserted into the middle of a road, and some routes that were  
suboptimal could be explained by not taking a junction boundary node.

Anyway, it looks like NOD 3 is all that's needed for routing from tile  
to tile -- no extra index in the gmapsupp.img or anything required.

Regarding the display problem: I cut the map up from a very small  
neighbourhood map which has some problems itself. In particular, it  
doesn't show street name popups. Larger maps seem to behave better, so  
my hope is that the display problem would go away on larger tiles.

Steve, do you intend for mkgmap to handle the cutting up eventually?  
Otherwise, my suggestion would be to leave this to external programs  
and have these put a tag (say mkgmap:boundary=yes) on the boundary  
nodes.

Cheers
Robert