[OSM-talk] tagging and rendering

Dave Stubbs osm.list at randomjunk.co.uk
Fri May 9 12:21:30 BST 2008


On Fri, May 9, 2008 at 11:30 AM, elvin ibbotson
<elvin.ibbotson at poco.org.uk> wrote:
> On 9 May 2008, at 11:05, Dave Stubbs wrote:
>
>>
>> As far as I see it there is no difference between mapping 11=autobahn,
>> and mapping motorway=autobahn.
>
> I think you missed the point. At present we have highway=motorway and I
> believe a German user would need to use these words. What I suggest is that
> if Potlatch is used on a German computer the user would be presented with a
> menu of road types starting with 'autobahn' while I would see a menu
> starting with 'motorway', both mapping to a database field of
> (hypothetically) 11. I can't see how 'motorway=autobahn' helps with
> anything.

No, you've missed the point.
Potlatch can just as easily say:
highway=motorway --> [german for highway]=autobahn

as it can:
highway=11 --> [german for highway]=autobahn

The mapping to numbers doesn't gain us anything. It doesn't let us do
anything we can't already do, or make it any easier as far as I can
see.

I think you were actually suggesting something like "type=11" -- where
10-20 means roads, 30-40 could mean railways etc. But as far as this
argument goes it doesn't really make much difference, other than
leaving us with a massive allocation problem which has been neatly
sidestepped by using free-form tagging.


>
>>> Places of worship could be mapped as cathedrals,
>>> churches, chapels, etc in Britain or as mosques, temples, shrines,
>>> whatever in the east.
>>
>> Um... except that Britain has quite a lot of mosques, temples and
>> shrines. These are different things, not the same things named
>> differently.
>
> Fair point - I didn't think that one through until I'd clicked SEND. Best
> not talk about religion, eh?
>
>>>
>> This is why we don't have (and have resisted) tags such as highway=red.
>
> Point missed again! I'm saying separate rendering from tagging. highway=red
> is exactly the opposite of what I'm suggesting.


Indeed point missed again.
We DON'T DO (sorry Richard) highway=red. We do highway=primary and you
can make that any colour you like... same as you can do with
highway=13/type=13 -- it makes no difference is my point. Numbering
the highways won't help.

>
>>
>> People have done customised renderings... see Freemap Slovakia for
>> example:
>>
>> http://www.freemap.sk/?lang=en&zoom=8&lat=48.49281826990847&lon=18.326709281821315&layers=BF0FFFFFFFT
>>
>
> Yes. Anyone can put up their own viewer, but I imagine most use the one on
> the OSM site and that could (possibly) render the content differently
> according to the keyboard language or to some locale setting in its control
> panel


It could yes. There are a couple of issues with this mostly to do with
actually maintaining the style sheets and providing the processing
power/disk space.


>>>
>>> Another aspect of the base data structure is that of level-of-detail
>>> (LoD) filtering. ...
>>>
>>
>> If you consider something like the cycle map where we have ncn as
>> the things that should show up at zoom level 6 instead, then we have
>> to apply different rules.
>
> No problemo! Special viewers like the cycle map would simply apply their own
> filters. And with well-structured data a map viewer could even have settings
> (eg. cycle routes on/off) allowing it to be customised by the user, making a
> proliferation of specialist viewers unnecessary.
>

Hmm.. yes, maybe. But the point of your e-mail was essentially
numbering everything, and that really doesn't help us with this goal.

Dave




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