OpenStreetMap Forum

RocketMan

Member

Registered: 2012-05-04

Posts: 249

O5M format question

Removed

Last edited by RocketMan (2015-06-29 10:34:26)

RocketMan

Member

Registered: 2012-05-04

Posts: 249

Re: O5M format question

Removed

Last edited by RocketMan (2015-06-29 10:34:35)

alex73

Member

From: Miensk. Bielaruś

Registered: 2011-11-15

Posts: 135

Re: O5M format question

One more question about o5m.

Wiki doesn't define deltas at all. I mean, "id of object", "latitude", "longitude" should use different "deltas". But it's mostly understandable.

By the http://wiki.openstreetmap.org/wiki/O5m, relation member id is "signed, delta-coded". The problem is: node, way and relation member uses different "delta base".

For example, if relation 1234 contains members:

way 26
way 28
node 41
relation 12
relation 13

then member IDs will be stored as:

way 26:    26
way 28:    2 (26+2)
node 41:   41(other delta base)
relation 12: 12(other delta base)
relation 13:  1 (12+1)

There is no any description about that in the http://wiki.openstreetmap.org/wiki/O5m. Is it correct way ? Or they should be stored as:

way 26:    26
way 28:    2 (26+2)
node 41:   13(28+13)
relation 12: -29(41-29)
relation 13:  1 (12+1)

If latest example is correct way, then osmconvert/osmupdate contain some bugs, because they are use different delta bases for different member types.