[Openstreetmap] RoadMap map generator / editor

[Simon Hewison]

Andy Robinson wrote:
> Similarly, to use your example, a one mile signature for the A1 might be
> very different from a one mile for Swanland Road. I assume also that when
> each track point is written to the database it can have an associated track
> ID assigned to it, perhaps the ID might be limited to a certain time or
> length of track to break up large tracks and simplify a signature.

Actually, in this case, no. I've known Swanland Road to be empty, and 
the A1(M) to be utterly congested. An average speed along Swanland Road 
might in some tracks be faster than down the motorway. That doesn't make 
Swanland Road the motorway, nor vice-versa.

> On the whole merging issue I'm going to spend some time with my spreadsheets
> on numerical analysis of lines and nodes (where line cross) using some gps
> data I'll collect from a set of street blocks and see what pops out. Anyone
> else actively working on this aspect?

Determining intersecting lines that genuinely meet at the same level is 
quite a different problem to determining intersecting lines. It can be 
done by context from other tracks.

(in the instance of a right-angle intersection of tracks, it's only if 
you see a track follow one of the approaching paths, and then turn left 
or right that you can be sure that there's some form of intersection there).

Even if you do see a level intersection, and can place a node for the 
intersection to join, you can still gather some more information about 
the intersection by statistical analysis of other tracks. Given a big 
enough sample size, it would be possible to infer a "no right turn" or 
"no left turn" on a junction.

--
Simon Hewison