[mkgmap-dev] [patch] inter-tile routing

Wed Feb 18 23:02:21 GMT 2009

On Feb 18, 2009, at 23:32, Mark Burton wrote:
> Robert, you're a genius - that completely fixes it for my test map.
> I can route across tile boundaries in all directions

Great!

> The current patch is good for evaluation but it still requires more  
> work because
> it won't behave well when boundary nodes are generated that are very  
> close to
> existing nodes. At the moment it throws the boundary node away which  
> isn't very
> optimal but should stop other things breaking.
>
> Robert, what's the constraints on min distances between nodes and  
> points?
>
> Can you have a node very close to the next point in a way?

I have no idea, really. There's something in the cGPSmapper  
documentation that claims a minimum distance between nodes of 5.4m.  
Alex pointed out that this is the minimal arc distance we can encode.

But I don't really see a reason in the data format for any kind of  
minimal distance (apart from the obvious minimum of 1 map unit  
(360/2**24 degrees)).

Does anything actually break if you disregard close nodes? Do these  
problems remain if RouteArc.convertMeters returns at least 1?

By the way, what I wrote earlier regarding boundary nodes and  
junctions is probably wrong -- the problems I based that guess on are  
very likely to have been caused by the unsorted boundary nodes.

Cheers
Robert