[OSM-talk] Tagging Seamarks

[Bernhard R. Fischer]

On Wednesday 18 August 2010 12:41:55 you wrote:
> Hi Bernhard,
> 
> thanks for your reply. This message has become longer than I initially
> expected, as I added some general thoughts of mine. Please do feel free to
> ignore those and concentrate on open questions. :)

Hi Arne,

I'll answer your mail completely, but in steps and not at once.

> > However, as an IT guy I prefer the Openseamp scheme to the offical one
> > because it is more modular from a technical point of view.
> 
> How is it more modular? How would modularity be useful in a practical
> sense? Can you provide an example or use case?
> 
> Being an IT guy myself, I think that maintainability (i. e. ease-of-use) of
> source code is very important. With tags being OSM's "source code", this
> makes me a big fan of the pragmatism that generally governs the OSM
> community's approach to finding and agreeing upon new tags.
> 
> That's also why I'd like to see OSM tags for marine data that are
> conceptually similar to OSM tags for land data. And that's also why I have
> every expectation that we'll eventually arrive at such a tagging scheme,
> however it may look. :)


In the Openseamap scheme everything is defined in the name of the key behind 
"seamark:" (e.g. "seamark:light.., seamark:type..., seamark:topmark,...).
This generates some kind of hierarchy within a flat database and you can select 
all seamark relevant data out of the database by retrieving all tags starting 
with "seamark:".

This is different to the official cbm proposal in which case you have to parse 
data before you can retrieve it because information about which tags are 
relevant is kept in the attribute values and the key names are not necessarily 
associated with each other (e.g. there is "seamark", "light", "buoy",...).


I still have criticism on the Openseamap scheme, e.g. for a seamark being a 
buoy or a beacon is just a property, hence, including the property in the key 
name is bad practice. For example seamark:type="buoy_lateral", 
seamark:buoy_lateral.shape="someshape". IMO it should have been defined like 
this: seamark:type=buoy_lateral, seamark.shape="someshape".
BTW, this is also true for the cbm scheme but unfortunately I wasn't involved 
into development of neither of those schemes.

My conclusion is that Openseamap scheme isn't perfect but it is technically 
better designed.

However, both schemes are fine-grained enough to be automatically changed to 
some other, better scheme in future.


Best regards,
Bernhard
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