Re: [Talk-us] [OSM-talk] Old Aerodromes

[Paul Johnson]

On Tue, Apr 12, 2016 at 2:29 PM, Elliott Plack 
wrote:

> I am glad this conversation has restarted. A few of you, (Me, Paul,
> others..) will recall a similar conversation on the openstreetmap-carto
> repo a few years ago where I noted that there are simply too many of these
> micro airports shown on the map. We discussed at great length how the
> relative importance of aerodromes could potentially be used for rendering.
>

I'm not sure what my original thoughts were but where I'm currently at on
this is if you're in a situation where all you understand mapwise is OSM
and you're in an emergency situation where the destination now is
"anywhere", then OSM is better than nothing, having at least runway
centerlines (and preferably the same for taxiways) and perimeters is better
(you can at least make a ballpark estimate of what *might* be a survivable
landing).  This of course, with the tacit understanding that we are not the
FAA (or whatever authority of record is relevant regionally) and no
rational pilot worth his flight credentials would use it for more than the
absolute most preliminary steps of planning.  Or as a decently accurate map
for Flightgear, since that flight simulator uses OSM data for scenery
already.

>From the ground, this isn't quite as important other than, say, being at
even a moderately sized airport like OSU in Norman or Riverside in Jenks
(both Oklahoma) where you might meet a friend in their plane at a specific
tiedown and not be sure where to drive inside the airport to the
appropriate tiedown/hangar.  Or at moderately large to huge airports,
finding a specific airport-related industry and residences only accessible
from a specific access in the perimeter (common with charter operators,
maintenance hangars, general aviation, military operators, etc; and
probably accounts for at least a hundred miles of near-airport GPXs and a
couple dozen miles of inside-perimeter GPX for me).

Bonus round a few years ago, attendees to Oklacon discovered the hard way
that Watonga Regional Airport is 1) a runway capable of emergency landing a
small commercial jetliner,  and 2) not secured.  Plus on at least one
commercial map provider, had it's taxiways, accesses and runways mapped as
a roadway, causing one especially confused person unfamiliar with the area
(or airports in general) to drive the length of the runway.   Fortunately,
Watonga's a *slllw* airport, and I don't recall hearing about anybody
or any flights in imminent danger (as was the case when Meigs unexpectedly
closed), so the incident only caused one person to be nicknamed Launchpad
for a couple days.  So having the airports properly tagged could be just as
important to *avoid* unintended traversal of airports as it can be to
intentionally navigate to a specific airport location.


> Given that map roulette is now handling these, I think this is a great
> time to revisit this discussion. If maprouletters can change all these
> point aerodromes to a polygon, then we can subjectively define airport
> importance using the shape size.
>

I'm all in favor of mapping these as polygons and mapping the on-the-ground
features, and possibly ground-based beacons where the identities can be
independently verified (shouldn't be hard, tune to it on a capable radio,
listen for the morse ident; in the midwest where there's basically noting
but tilled field, these might also serve as a potential landmark as much as
a lone tree does).  There's not much point in trying to map flight
restrictions or paths, though, since there's no real good way to identify
from the ground what these are.

Like lakes and parks, editors probably ought to show a visible warning that
things are Not Right when mapped as a node.
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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Elliott Plack]

I am glad this conversation has restarted. A few of you, (Me, Paul,
others..) will recall a similar conversation on the openstreetmap-carto
repo a few years ago where I noted that there are simply too many of these
micro airports shown on the map. We discussed at great length how the
relative importance of aerodromes could potentially be used for rendering.

Given that map roulette is now handling these, I think this is a great time
to revisit this discussion. If maprouletters can change all these point
aerodromes to a polygon, then we can subjectively define airport importance
using the shape size.

Read up on GitHub:
https://github.com/gravitystorm/openstreetmap-carto/issues/1143


On Tue, Apr 12, 2016 at 1:42 PM Wolfgang Zenker 
wrote:

> * Paul Norman  [160412 17:27]:
> > On 4/12/2016 2:40 AM, Christoph Hormann wrote:
> >> On Tuesday 12 April 2016, Martijn van Exel wrote:
>  I was mapping some rural area in the U.S. and noticed, not for the
>  first time, an aerodrome node in the middle of a field where there is
>  obviously no airport or airfield.
>
> >> I am not sure here.  For small airfields the aeroway=aerodrome feature
> >> is a fairly abstract thing essentially indicating only that this is a
> >> place where aircrafts start or land.  This is not generally something
> >> that can be reliably determined from imagery.
>
> > You can't reliably find small airfields from imagery, but I've found it
> > possible to verify a lack of airfields from it. I pass though
> > agricultural areas, and the airfields that are still active all appear
> > somehow on imagery, even if it's just an area where the ground cover is
> > different. On the other hand, some of the aeroway=aerodrome we have data
> > for include points in fields of corn, residential areas, and stands of
> > trees.
>
> One added problem here is that the coordinates of imported data are
> not always that good. As an example check Zortman Airport
> http://www.openstreetmap.org/node/1042048666
> The original import was more than half a mile off.
>
> Wolfgang
>
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>
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http://elliottplack.me
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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Paul Johnson]

On Tue, Apr 12, 2016 at 10:21 AM, Wolfgang Zenker  wrote:

> Hi,
>
> * Martijn van Exel  [160412 16:29]:
> > Thanks for the feedback. I understand that the existence of an small
> airfield can be hard to verify from imagery - [..]
>
> one more thing to check: If the node was imported from GNIS, check the GNIS
> website searching for the feature id. In some cases that I have seen the
> GNIS entry had moved to "historical" status since the feature had been
> imported. If a feature in GNIS has "(historical)" at the end of the name
> field it means the feature does no longer exist, so we can delete it in
> OSM.
>

Inside Tulsa City and vicinity, I've ground-surveyed the airports around
here.  Harvey Young was probably the most interesting case, since everyone
I asked said it had closed years before.  Nope!  Still operational.
Another unlikely one that I found was Silverwood Ultralight Airport, which
I was very certain that if the swamp hadn't got it, the elevated portion of
the Liberty Parkway did.  It's actually a mile south of where GNIS thought
it was, but still has the Liberty Parkway as a flightpath obstruction!
It's pretty much a rancher's hairy-short dirt strip, not uncomplicated by
the fact there's numerous oak trees and an elevated motorway immediately
adjacent, but still is operational with the owner and his friends.

On the extreme opposite end of the spectrum was a third international
airport in Oklahoma.  Which...not entirely implausible, Tulsa's not
gigantic nor has scheduled overseas commercial passenger flights outside
the US borders that I'm aware of, but does have customs mostly for shipping
and flight crews, as Tulsa's the maintenance base for all of American
Airlines major repairs, as well as Lufthansa's US operations, and has
shipping flights on both UPS and FedEx, as well as direct nonstop shipping
to and from Kazakstan because NASA and eastern Oklahoma's deeply entrenched
space industry (at it's peak building over 90% of what went into the space
shuttles and it's rocket boosters, everything from mom-and-pops that went
out of business with the end of the shuttle program right up through NORDAM
and Rocketdyne).  The other's Will Rogers World Airport in Oklahoma City.
The third?  Doesn't, and never has, existed except on some dusty TIGER
records at the location of an abandoned farmhouse in the middle of a
field.  Everything within a several mile radius is regularly plowed
agricultural field with no evidence that even an ultralight could use it,
and unpaved, graded county line section roads.  Deleted...
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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Wolfgang Zenker]

* Paul Norman  [160412 17:27]:
> On 4/12/2016 2:40 AM, Christoph Hormann wrote:
>> On Tuesday 12 April 2016, Martijn van Exel wrote:
 I was mapping some rural area in the U.S. and noticed, not for the
 first time, an aerodrome node in the middle of a field where there is
 obviously no airport or airfield.

>> I am not sure here.  For small airfields the aeroway=aerodrome feature
>> is a fairly abstract thing essentially indicating only that this is a
>> place where aircrafts start or land.  This is not generally something
>> that can be reliably determined from imagery.

> You can't reliably find small airfields from imagery, but I've found it 
> possible to verify a lack of airfields from it. I pass though 
> agricultural areas, and the airfields that are still active all appear 
> somehow on imagery, even if it's just an area where the ground cover is 
> different. On the other hand, some of the aeroway=aerodrome we have data 
> for include points in fields of corn, residential areas, and stands of 
> trees.

One added problem here is that the coordinates of imported data are
not always that good. As an example check Zortman Airport
http://www.openstreetmap.org/node/1042048666
The original import was more than half a mile off.

Wolfgang

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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Christoph Hormann]

On Tuesday 12 April 2016, Paul Norman wrote:
> >
> > I am not sure here.  For small airfields the aeroway=aerodrome
> > feature is a fairly abstract thing essentially indicating only that
> > this is a place where aircrafts start or land.  This is not
> > generally something that can be reliably determined from imagery.
>
> You can't reliably find small airfields from imagery, but I've found
> it possible to verify a lack of airfields from it.

I agree this can be possible based on the considerations that it would 
be impossible to properly land an aircraft there (i.e. identification 
of the lack of possibility for an airfield to exist).  But it should be 
made clear to the mappers that with something as abstract as an 
airfield the lack of positive indications for the presence of a feature 
is not generally sufficient basis for removing data without local 
knowledge or identifying the original source of the data, for example a 
certain import, as unreliable.

For example i'd consider a stretch of road in a remote area that is 
frequently used for landing small aircraft a valid case of 
aeroway=aerodrome - likewise for a dry riverbed or lakebed, all of 
which will usually lack any visual signs for being used for this 
purpose unless an aircraft happens to be there the moment you look.

-- 
Christoph Hormann
http://www.imagico.de/

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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Paul Norman]

On 4/12/2016 2:40 AM, Christoph Hormann wrote:

On Tuesday 12 April 2016, Martijn van Exel wrote:

>Hi,
>
>I was mapping some rural area in the U.S. and noticed, not for the
>first time, an aerodrome node in the middle of a field where there is
>obviously no airport or airfield.

I am not sure here.  For small airfields the aeroway=aerodrome feature
is a fairly abstract thing essentially indicating only that this is a
place where aircrafts start or land.  This is not generally something
that can be reliably determined from imagery.


You can't reliably find small airfields from imagery, but I've found it 
possible to verify a lack of airfields from it. I pass though 
agricultural areas, and the airfields that are still active all appear 
somehow on imagery, even if it's just an area where the ground cover is 
different. On the other hand, some of the aeroway=aerodrome we have data 
for include points in fields of corn, residential areas, and stands of 
trees.


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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Wolfgang Zenker]

Hi,

* Martijn van Exel  [160412 16:29]:
> Thanks for the feedback. I understand that the existence of an small airfield 
> can be hard to verify from imagery - [..]

one more thing to check: If the node was imported from GNIS, check the GNIS
website searching for the feature id. In some cases that I have seen the
GNIS entry had moved to "historical" status since the feature had been
imported. If a feature in GNIS has "(historical)" at the end of the name
field it means the feature does no longer exist, so we can delete it in OSM.

Wolfgang

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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Martijn van Exel]

Hi all, 

Thanks for the feedback. I understand that the existence of an small airfield 
can be hard to verify from imagery - but I am also wondering what the value of 
this unverified and stale data is to OSM. If they were mapper surveyed nodes to 
begin with I would perhaps feel the need to be more cautious in removing them. 
I looked at perhaps 30 of them, looking them up on various airport related web 
sites, and ~70% of them were private air strips with no public access from air 
or ground. So those being fundamentally unverifiable (unless there is a sign or 
some structures on the ground that would make it so) I would see no problem 
deleting them. 

I like the suggestion for encouraging additional mapping (runways) if visible 
and this is already part of the instruction, let me know if that could be 
clearer.

I am not so concerned with rendering - that’s not what we map for.

Martijn

> On Apr 12, 2016, at 3:40 AM, Christoph Hormann  wrote:
> 
> On Tuesday 12 April 2016, Martijn van Exel wrote:
>> Hi,
>> 
>> I was mapping some rural area in the U.S. and noticed, not for the
>> first time, an aerodrome node in the middle of a field where there is
>> obviously no airport or airfield.
> 
> I am not sure here.  For small airfields the aeroway=aerodrome feature 
> is a fairly abstract thing essentially indicating only that this is a 
> place where aircrafts start or land.  This is not generally something 
> that can be reliably determined from imagery.
> 
> This is also a problem for map rendering - map styles use these features 
> to place labels and icons but these features are generally too 
> ill-defined and undifferentiated to do this properly.
> 
> The real observable feature of an airfield is the perimeter fence or 
> other form of delineation which then makes it a landuse mapping but 
> this only works for actively maintained airfields with a clearly 
> visible outline.  Otherwise the observable feature of an airfield is 
> the runway - mapping this is much better defined and more useful 
> information-wise than the airfield itself.
> 
> So the challenge would IMO make more sense if it would encourage mapping 
> runways if they are visible rather than removing an aerodrome based on 
> the fact that it is not visible on imagery.
> 
> See also here for a different angle on the problems of aeroway=aerodrome 
> as it is currently mapped:
> 
> https://github.com/gravitystorm/openstreetmap-carto/issues/1143
> 
> -- 
> Christoph Hormann
> http://www.imagico.de/
> 
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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Christoph Hormann]

On Tuesday 12 April 2016, Martijn van Exel wrote:
> Hi,
>
> I was mapping some rural area in the U.S. and noticed, not for the
> first time, an aerodrome node in the middle of a field where there is
> obviously no airport or airfield.

I am not sure here.  For small airfields the aeroway=aerodrome feature 
is a fairly abstract thing essentially indicating only that this is a 
place where aircrafts start or land.  This is not generally something 
that can be reliably determined from imagery.

This is also a problem for map rendering - map styles use these features 
to place labels and icons but these features are generally too 
ill-defined and undifferentiated to do this properly.

The real observable feature of an airfield is the perimeter fence or 
other form of delineation which then makes it a landuse mapping but 
this only works for actively maintained airfields with a clearly 
visible outline.  Otherwise the observable feature of an airfield is 
the runway - mapping this is much better defined and more useful 
information-wise than the airfield itself.

So the challenge would IMO make more sense if it would encourage mapping 
runways if they are visible rather than removing an aerodrome based on 
the fact that it is not visible on imagery.

See also here for a different angle on the problems of aeroway=aerodrome 
as it is currently mapped:

https://github.com/gravitystorm/openstreetmap-carto/issues/1143

-- 
Christoph Hormann
http://www.imagico.de/

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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Paul Johnson]

On Tue, Apr 12, 2016 at 4:19 AM, Martin Koppenhoefer  wrote:

>
> 2016-04-12 11:00 GMT+02:00 Paul Johnson :
>
>> Can we really be sure there is no airfield, just because we don't see
>>> anything in the aerial imagery? Isn't this maybe also a legal question
>>> besides physical characteristics?
>>>
>>
>> Well, if it's not on the ground, what are we to map?
>>
>
>
> E.g. a right of way (not sure if this is the correct term here)? Typically
> aircraft for example have to avoid the surroundings of airfields if they
> are not starting or landing there, you might not fly with your kite or
> drone nearby, etc.
>

But now we're getting into something for which there's NOTAMs and
established official data on, in a highly variable space, and one that
is generally
regarded as out of scope of this project
.
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Re: [Talk-us] [OSM-talk] Old Aerodromes

[Paul Johnson]

On Tue, Apr 12, 2016 at 3:23 AM, Martin Koppenhoefer  wrote:

>
> 2016-04-12 4:50 GMT+02:00 Martijn van Exel :
>
>> I was mapping some rural area in the U.S. and noticed, not for the first
>> time, an aerodrome node in the middle of a field where there is obviously
>> no airport or airfield.
>
>
> Can we really be sure there is no airfield, just because we don't see
> anything in the aerial imagery? Isn't this maybe also a legal question
> besides physical characteristics?
>

Well, if it's not on the ground, what are we to map?
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