[OSM-talk] RFC - model aerodrome

[Lester Caine]

Robin Paulson wrote:
> this proposal has been languishing for 2+ months now, with little discussion
> 
> http://wiki.openstreetmap.org/index.php/Proposed_features/Model%27s_Aerodrome
> 
> please could i get some comments

I've posted comments there but I think that we need to get a higher level 
discussion under way on the hierarchy of the tagging system. And I'm not sure 
where to start it? Here or create a wiki page?

I'll outline things here.

There are two areas to be covered which are probably separate discussions but 
they dovetail together logically. Simply FINDING a tag is currently tedious 
and then knowing what to use with that tag becomes even more fun :(

We have a number of top keys which I think need to be combined and layered to 
give a more logical progression.

Going back to basics we have two types of element to manage a linear structure 
or an area ( a node is just a special case of an area, but even that may well 
have an area at a large enough scale ). The only difference between the two is 
  that the line segments on an area must meet at the ends and while the M25 
may be a circle, the area within it is different to the route itself.

highway, waterway and railway are essentially 'way' type=xxx to which cycle, 
track, aerial can then be added. But rather than being too drastic, I think 
that three basic definitions can be applied to keep top level more manageable.

highway - unconstrained route
railway - constrained by track ( should be trackway but that will confuse )
waterway - constrained by water course

Cycleway is just a type of highway
Tracktype is just a secondary key for a number of highway types
Aerialway is a type of railway

There *IS* a case for simply combining all three, but apart from a few special 
cases the general rule is that vehicles do not move from one type to the 
other. I'll ignore amphibious cars, and the busway discussion identifies that 
only specially modified vehicles should move from highway to trackway.

Airports are obviously a slight ambiguity since they have highways for taxiing 
and for taking off, but an airport should be a bounded area containing those 
features. I think this actually highlights the problem with the current 
structure where aeroway=aerodrome is defined for nodes when in fact it is an area?

This is where the other discussion dovetails in ...

All of the component parts of an airport 'is_in' the airport, but this is 
currently not managed properly. In the same way that country, county/state, 
town, locality and the like are not managed.

We need as a matter of urgency to correctly manage the relationship between 
areas and the structures they contain. YES there are problems where an area 
straddles other areas, but that is just a special case that needs handling. If 
I search for all 'model_aerodrome' in the UK that is a reasonable request, but 
having to add 'is_in' to every tag is not the solution and needs to stopped now?

Once we have the concept of area, landuse becomes obvious, and amenity in that 
area follows on?
retail->shop ? cafe and the like
leisure->sport ? even where professional activity the watching of is leisure
military->military

Obviously linear features like power lines, underground storm drains and the 
like need catering for but those type of features may just a special case?

( I'd still like to see numeric tagging with a multilingual title table even 
though I only speak English but that will come another day, for the moment we 
have to use English keys for the translation table :(
- it would be nice if the translated versions of Map_Features had a column for 
the translated tag names! )

-- 
Lester Caine - G8HFL
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