[OSM-talk] Tagging Seamarks

[Arne Johannessen]

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. :)


Bernhard R. Fischer wrote:
> 
> [...] Also FT puts just an overlay on top of the Openstreetmap map but 
> Openseamap completely renders a seamap with focus on seamap features.

Not sure what you're referring to. I mean, <http://www.freietonne.de/seekarte/> and <http://openseamap.org/> are both "just" overlays on top of the standard Mapnik OSM rendering, right?


> [...]
> This is the reason why I personally favor Openseamap more than FT. In 
> addition, FT is focused more on inland waterways.

Personally, I favour neither one of those projects. I'd just like to add some marine data to OSM, and don't fancy doing it twice (once per tagging scheme). Besides, there are clear technological issues with this kind of redundancy.

I'm also thinking about writing a new renderer (or renderer style) for marine data in OSM, and find the existing documentation of the tagging schemes in use less than optimal for that purpose.


> A further question for me is what is "official" and what is "private"?
> Both of those tagging schemes are similar although the structure is different, 
> as you mentioned.

As far as I can see, the similarities pretty much end with the fact that they both can be used for buoys and beacons and stuff. Sure, some of the strings look the same, but because of the different structure this merely adds to the confusion.

Speaking of the structure: I also have the impression, that the OSeaM scheme views all of their tags as non-optional, resulting in a true proliferation of tags even for otherwise simple objects. But I may be wrong on that. The Wiki appears to be silent on the matter.

Anyway, what I meant by "official" is something like the Map Features -- a single go-to-page with most relevant links to the consensus of the OSM community as far as tagging is concerned, enabling newbies to just go ahead and start working. With "private" I meant a tagging scheme that is not used in OSM except by a certain group of people for their own purposes. But as I said, I may have misunderstood the earlier discussion on this matter on [talk-de].


> And, what is IMO much more important, the Openseamap scheme 
> is already rendered on OpenSeamap which is not true for the other one and I 
> stick with the opinion of the Openseamp guys: a seamap should be rendered 
> different than a street map because different objects are important.

Sorry, I'm not a member of either project and hence am not very well versed in their technology. Which renderer are you presently referring to?

I mean, as far as I know, both projects have their own slippy maps on their home pages (see above), but at this point neither of them really looks different than a street map because they both use the default Mapnik rendering style as base.

But then again, there also appear to be existing solutions to export marine data from OSM to embedded systems (hand-held GPSs, chart plotters etc.), so the renderer landscape could be said to be a bit more diverse than just consisting of a few slippy maps. Perhaps you're referring to one of these exported OSM displays..?

I agree with you BTW: a marine map should eventually be rendered different from land maps, no matter whether the sea or inland waterways are depicted.


> 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. :)


> Thus, I hope that people 
> out there do not still ignore the Openseamap scheme. After all, I translated 
> it into English ;)

Ah, thanks for doing that. Hopefully it will facilitate some discussion.


> Regarding S-57: I think what they mean is that they orient on the S-57 schemes 
> in respect to which attributes exist on which objects.

Yes, maybe that's what happened.

But S-57 is very convoluted and very specific to ENCs, even just far as the object attributes are concerned. OSM can be a lot more flexible. We should make use of that flexibility. I for one think it would be a mistake to have another data format's constraints carry over into OSM.

Cheers,
Arne

-- 
Arne Johannessen