[Openstreetmap] openstreetmap.org updates, ontology stuff

[Matt Amos]

On Saturday 19 March 2005 10:18, Nick Whitelegg wrote:
> On Saturday 19 Mar 2005 00:34, Matt Amos wrote:
> What I had in mind was a bitwise scheme something like this, to
> easily generate maps from the data by bitwise operations:
>
> Bit 1 Accessible to foot?
> Bit 2 Accessible to bikes?
> Bit 3 Accessible to horses?

this is useful, but i'd do it as:

key: accessible_on_foot  true | false
key: accessible_to_cycle  true | false
key: accessible_on_horse true | false

so a query for horse tracks would be something like "select ... from 
routes, routeinfo where routes.id = routeinfo.id and 
routeinfo.key="accessible_on_horse" and routeinfo.value=1"

> 000 = no vehicular access (e.g. footpath)
> 001 = "byway" (countryside track open to off-road vehicles)
> 010 = residential road
> 011 = minor road used by through traffic (e.g. country lane)
> 100 = B road
> 101 = A road
> 110 = spare
> 111 = motorway

this is basically an ontology, though. what if there is more than one 
type of motorway and more than 2 types of main road? how do you 
attach speed limit info? (e.g: autobahn, motorway and route nationale 
are all motorways, but have different speed limits)

> > why have numeric id's at all?
>
> Numeric IDs would be the most efficient way (I'd have thought) to
> keep each individual segment unique.

i totally agree that numeric id's are best to keep segments unique, 
but i think meta-data is better dealt with in a more flexible format.

> Anyway, hope this wasn't too long but it's my thoughts.

i think now is definitely the time to be discussing these issues, as 
they'll have a massive effect on the software and APIs that we'll be 
implementing.

cya,

matt
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