[mkgmap-dev] routing error example

Tue Jul 7 08:34:14 BST 2009

Hi Garvan,

> I have made a cut down sample map showing an error in routing as 
> displayed in mapsource. The source is in polish format, and includes the 
> junction where the errors are found, and a portion of a city to the 
> south. If I delete more roads from the city, the error disappears, even 
> though the error itself is apparently north of the city. The routing 
> works correctly in gpsmapedit.
>
> 
> The graphic file shows the junction where the errors are happening. The 
> route should be west and south from one waypoint to the other, and 
> instead it jumps about, sometimes following roads, sometimes making 
> straight-line jumps.

I can't find the point on the map the graphic is showing. What are the
coordinates of the junction between the two flags?

> In another post, I was told there are “short arcs” errors in the polish 
> format input. Could somebody describe exactly what a short arc is, 
> (length between nodes, length between routing nodes or something else, 
> and what is the minimum length arc)?

A short arc is where two routing nodes are so close together that they
are located at the same point. The minimum distance between routing
nodes is approx 2.5 metres.

> gpsmapedit reports that all nodes are greater than 5m apart in the input.

Good, then it's probably not short arcs that are the issue here.

Cheers,

Mark