[Tagging] Catchment Areas

Christopher Baines cbaines8 at gmail.com
Sat Dec 1 15:00:06 GMT 2012

On Sat, 2012-12-01 at 09:24 -0500, Greg Troxel wrote:
> The problem with representing catchment areas in OSM is that it rapidly
> gets into the "one database, one man's treasure, another's junk"
> problem, because it leads to objects for things that don't really exist,
> but are only enshrined in policies of various kinds.

These things that don't exist, are still really important. Consider for
instance a map without international borders, turn restrictions on
roads, and probably some more... 

> I can see the point that in mapping a developing country for health
> care, these boundaries might be very important to map users and editors
> relative to other data.  But if I think about the area around me, there
> are probably 5 places that will deliver food, and adding 5 polygons to
> the map for that already seems unreasonable.  My city friends probably
> have hundreds of places that will deliver.

In a large city, most food places will probably deliver to certain
already mapped areas, hence you only need to add the tag pointing to a
pre-existing object, not create 5 polygons. You also don't have to have
this tag on all services with catchment areas, it can just be used when

> Also, it seems that catchment area is a marketing term, and the concepts
> of
>   "to where will we deliver, rather than refusing the order"
>   "from what areas (of home address) will we treat patients"
>   "from what areas do we consider ourself to be the hospital of record"
> are all very different questions.  It may be that what's needed for is a
> more traditional GIS analysis showing distance to facilities from
> everywhere.

I have little knowledge about GIS, but it seems to me like the above
questions all involve the same data, the Catchment Area of the service.
When writing the proposal, I was trying to think about the definition of
catchment area on Wikipedia [1]

> I suspect the real discusion will be about adding polygons to be targets
> of this tag, rather than the tag itself.

I might not have understood your point here, but I imagine most of the
catchment areas will be best mapped as multipolygon relations at least
in high density areas, hence not cluttering up current editors. 

1: https://en.wikipedia.org/wiki/Catchment_area_%28human_geography%29

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