W dniu 21 września 2014 02:10 użytkownik Tom Pfeifer napisał:
> Navigation software is pretty able to consider a short list of specific 
> pavings
> as 'paved' and another short list as 'unpaved', they are already structured 
> in the
> wiki.

> OsmAnd, as a popular navigation software, does so, and in the pre-1.9 
> nightlies you
> can switch on colour coding for different surfaces.

>> the software can check the value of the surface key, but in practice most 
>> (all?)
>> of the navigation software only checks for a subset of all the possible 
>> values
>> the surface key can have.

> Could you please support your argument with examples of such software, and
> why such incompleteness cannot be fixed within the router/renderer?

Didn’t want to name particular software, but if you ask, then OsmAnd 1.8.3 
thinks that
highway=tertiary + surface=dirt is a paved way, and setting “avoid unpaved 
roads” in its
configuration doesn’t prevent it from routing through such a road (car 
navigation mode).

Please look at this issue:
https://code.google.com/p/osmand/issues/detail?id=1956

As you can see, they have “fixed” the issue more than a year ago, in version 
1.4.1.
Then I forgot about this and didn’t check whether it really worked.

Yes, I should have probably reopened the issue and tell them that they didn’t 
really understand
what it was all about. But on the other hand, I believe I was clear enough in 
my description.
I stated clearly that the problem is that they do not support _various 
different_ values
of the "surface" key, yet they only went for adding support for _one most 
general_ value.

I had pointed them to that very long list of possible values for “unpaved” 
surfaces, yet they
have decided to add support for only one of them.

So, again:
> Navigation software is pretty able to consider a short list of specific 
> pavings
> as 'paved' and another short list as 'unpaved', they are already structured 
> in the
> wiki.

True.

> OsmAnd, as a popular navigation software, does so

Untrue, unfortunately.

And answering this particular question of yours:
> [...] and why such incompleteness cannot be fixed within the router/renderer?

Don’t as me. They apparently have chosen not to.


Moving on:
>> The default value
>> of the paved key for highways could be yes, so that it would be consistent 
>> with the
>> assumption that highways in general are paved.

> This does not work as a general assumption.
> I would assume a motorway as paved, but a track or path as unpaved, unless 
> shown otherwise.

Yes, I forgot that the highway tag is used also for these. So this would be a 
bad idea
indeed to assume that highways are paved by default.

>> Also, the surface=paved could also implicate paved=yes
>> and similarly surface=unpaved could implicate paved=no, so that duplication 
>> of the
>> information could be avoided when the generic paved and unpaved values are 
>> set for the surface key.

> You are just arguing against your proposal.

I wouldn’t agree that I’m arguing against my proposal here. I’m supplementing 
it.

> As we have surface=paved we don't need paved=yes.

Yes, that’s what I meant – if a highway has surface=paved, then it doesn’t need 
paved=yes.

> And surface=asphalt implies paved.

And what about surface=dirt? Doesn’t seem to mean surface=unpaved for everybody.


Besides all the above, and besides all the answers all of you have written,
another thing has just came to my mind – don't you think that using the 
“surface” key
for saying _either_ that a highway is paved/unpaved _or_ what particular surface
the highway has, is a bit inconsistent? What I mean: don’t you think that a 
property
called “surface” should describe what highway is made of/consists of (asphalt,
paving stones, grass, mud, dirt, ice, etc.) and not how it has been made (it 
has been
_paved_ or has been left _unpaved_)? In my opinion these are fundamentally two 
different
properties (although one of them is a derivative of the other).


Regards,
Tomek


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