Re: [OSM-talk] OSM needs a measure for completeness

[Martijn van Exel]

This would fit in very well with the annotation system discussed in  
the 'Recent Edits' thread not too long ago.

-- 
martijn van exel -+- [EMAIL PROTECTED] -+- http://www.schaaltreinen.nl/

Op 3 feb 2008, om 20:16 heeft Dirk-Lüder Kreie het volgende geschreven:

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> Frederik Ramm schrieb:
>> Whereever possible I'd like to try and have this completeness  
>> assessed
>> by people *other* than those who did the mapping; maybe through a web
>> interface where casual visitors can check their area of residence and
>> rubber-stamp it (or note down complaints).
>
> I very much like this idea. Alongside with a simple way of correcting
> spelling errors without needing to go to any full-fledged editor.
> Of course there are some places that are spelt differently than many
> people would think. For example Neustadtswall vs Neustadtcontrescarpe
> The former is commonly referred to as Neustadtwall, for example.
>
> - --
>
> Dirk-Lüder "Deelkar" Kreie
> Bremen - 53.0952°N 8.8652°E
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Re: [OSM-talk] OSM needs a measure for completeness

[Martin Trautmann]

Chris Morley wrote:

> I have started a new thread with a measure for completeness in the title
> because this is an important topic for OSM. But the response to the
> recent posts quoted above, and my raising of it last July, has been only
> luke-warm.

I've added http://wiki.openstreetmap.org/index.php/Straßenschlüssel to 
the wiki, a German description how to measure completeness:

Completeness may be verified most easily for roads.
Primary/secondary/.. are listed on most maps. The approach here is 
focused more on residential:

1) various sources for lists of roads:

You may take names from city maps, get them from postal area codes, from 
telephone books, from address collections and many other sources.

2) encoding of valuable stuff

There's a German system how an address may be encoded. It's based on the 
abbreviations which are used for car plates, an official key for the 
community, an official list of roads, the house number and the first 
letters of one's name. This official list of roads assigns a five digit 
number. This list does include especially all addresses where someone 
lives. Thus minor tracks or not necessarily included: The finer details 
differ from community to community. Roads outside the residential areas 
are not part of these lists.

This encoding system is called "FEIN" or "EIN". It is recommended by the 
police. The road lists (German: "Straßenschlüssel") are used for other 
tasks as well (statistics, ownership, tax, maintenance, ...).

The German cycling club (ADFC) uses this system for bicycle encoding as 
a matter of theft protection. That's why they offer a web service to 
obtain the personal EIN code for anyone: 


3) opengeodb

On the ADFC site there's a another web interface for the opengeodb data 
maintenance, which holds information about many places in Central Europe 
. These combined datas, the 
road lists and the opengeodb info, can be used to match OSM data and 
highway tags. The result is a certain measure of completeness, how many 
percent of those roads have been tagged by now. It does not include any 
other stuff that is worth tagging (where it may be more difficult how to 
measure completeness) and it does lack many tracks or details about the 
quality of the data (lanes, speed limits, total length etc.)

Three larger federal states have been processed by now, see
http://wiki.openstreetmap.org/index.php/Category:Statistics

-> Baden-Württemberg
-> Nordrhein-Westfalen / North Rhine-Westphalia
-> Bayern / Bavaria
-> Oberbayern
-> Niederbayern

One result is a number in percent how many of those residential roads 
have been tagged. As another result, a second phase may be applied to 
identify incorrect spellings: see
http://wiki.openstreetmap.org/index.php/Talk:Baden-Württemberg#Korrekturvorschläge
 
(suggestions for fixes)

I guess that road lists are available almost everywhere. Does anyone 
else do a match for larger regions, instead of the local area?

- Martin

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Re: [OSM-talk] OSM needs a measure for completeness

[Dirk-Lüder Kreie]

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Frederik Ramm schrieb:
> Whereever possible I'd like to try and have this completeness assessed
> by people *other* than those who did the mapping; maybe through a web
> interface where casual visitors can check their area of residence and
> rubber-stamp it (or note down complaints).

I very much like this idea. Alongside with a simple way of correcting
spelling errors without needing to go to any full-fledged editor.
Of course there are some places that are spelt differently than many
people would think. For example Neustadtswall vs Neustadtcontrescarpe
The former is commonly referred to as Neustadtwall, for example.

- --

Dirk-Lüder "Deelkar" Kreie
Bremen - 53.0952°N 8.8652°E

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[OSM-talk] OSM needs a measure for completeness

[grungelborz]

Some comments regarding the completeness thread: 

For Munich we currently use wiki pages to track the completeness: 
http://wiki.openstreetmap.org/index.php/Landkreis_M%C3%BCnchen (in German 
but Google translates it quite ok). Wiki pages were used because
they are simpler to set up than anything else.

It uses just a very rough scale as IMO a finer scale is not useful if 
the completeness is to estimated. The percentage values that are estimated 
usually
do not tell much about the remaining effort. On the other hand the 
map can be devided in small areas (< 1/2 d effort) that can be easily 
evaluated. 
The tables just focuses on the most important things like street names, car 
navigation and bike navigation). I believe this is enough so that people will 
start 
using the map. 

It seems that not all mappers want to take the effort to enter 
areas into the tables. Most likely reason is that its not that simple 
to find the name for the area that has been mapped. Still its better than 
nothing. 

A good technical solution to assign completion-states might be similar to 
solution for the render-requests at tiles-at-home: When the user clicks a 
tile with some modifier keys a dialog appears that allows to select a 
completion 
level and to add some comments. This would also allow people without osm 
account to report errors. 

Grungelborz 


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Re: [OSM-talk] OSM needs a measure for completeness

[Gregory]

What about one indicator of completness being automatic: How many key/value
pairs per way or node.
So you have the standard: this is claimed to be 80% complete by user:Bob (or
this is validated to be 75% complete/accurate by user:Fred)
Then you have addtionally: this as information to a level of 20%

I'm not sure how the levels would work.
Maybe 10% means ways have a highway value and a name value, nodes have a
name value and something else, unless the node is attached to a way it
doesn't matter.
50% means at least half of the ways/nodes have an additional 3 tags.

Obviously it would need some work to get the levels defined right but
hopefully you get the idea. Either the level definitions would have to be
changed about once a year (due to tag proposals, more data being able to be
entered), or they would have to be relative to the number of approved tags.


On 13/01/2008, Lars Aronsson <[EMAIL PROTECTED]> wrote:
>
> Dair Grant wrote:
>
> > Good point! Which makes it all the more important to have a
> > mechanism for marking it as such, if only to reduce the number
> > of people who make pointless trips to the middle of nowhere to
> > confirm there's nothing there...
>
> There are very few places with "nothing" in them.  There might be
> creeks or peaks or vegetation types.  But what we can do is to
> define layers such as "all secondary or bigger roads" or "all
> churches, cemetaries and memorial monuments" and indicate whether
> these feature groups have been covered in an area.
>
>
> --
>   Lars Aronsson ([EMAIL PROTECTED])
>   Aronsson Datateknik - http://aronsson.se
>
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-- 
Gregory
[EMAIL PROTECTED]
http://www.livingwithdragons.com
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Re: [OSM-talk] OSM needs a measure for completeness

[Lars Aronsson]

Dair Grant wrote:

> Good point! Which makes it all the more important to have a 
> mechanism for marking it as such, if only to reduce the number 
> of people who make pointless trips to the middle of nowhere to 
> confirm there's nothing there...

There are very few places with "nothing" in them.  There might be 
creeks or peaks or vegetation types.  But what we can do is to 
define layers such as "all secondary or bigger roads" or "all 
churches, cemetaries and memorial monuments" and indicate whether 
these feature groups have been covered in an area.


-- 
  Lars Aronsson ([EMAIL PROTECTED])
  Aronsson Datateknik - http://aronsson.se

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Re: [OSM-talk] OSM needs a measure for completeness

[Martin Trautmann]

graham wrote:
> 80n wrote:
> 
>> In a sense I'm already doing this.  The very last thing I do when I've
>> completed an area is to add landuse=residential (only where appropriate,
>> of course).  I could easily add complete=level-n to this landuse boundary.
>>
> 
> Surely completeness is relative to purpose? I have areas where all roads
> between settlements are filled in but not the settlements, other urban
> areas where all roads are filled in and named, others where all roads
> and footpaths are complete. 

I feel that completeness of settlements can not be achieved as long as 
roads are incomplete. Thus first level should be completeness of the 
road net. Most important next for me is appropriate tags for routing, 
such as speed limits or "bicycle=yes".

- Martin

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Re: [OSM-talk] OSM needs a measure for completeness

[Bruce Cowan]

On Sat, 2008-01-12 at 19:08 +, graham wrote:
> Surely completeness is relative to purpose? I have areas where all roads
> between settlements are filled in but not the settlements, other urban
> areas where all roads are filled in and named, others where all roads
> and footpaths are complete. I haven't yet done any areas which have
> complete traffic lights, pedestrian crossings, turn restrictions, bus
> routes, administrative boundaries, or navigational information for
> waterways. The possible purposes are pretty orthogonal - rather than a
> set of numbered completeness, you'd need to allow multiple
> 'complete_for=purpose' tags. And if you attach that to landuse
> boundaries, what do you do in large urban areas where it's all residential?

I had a few roads which I considered "complete", but revisiting them a
few months ago, I noticed they were of fairly low quality (node density
wise). This could apply to any area.

As a sideline, I wonder if wrong GPS traces will become a problem. In
this scenario, imagine a road changing position (like the A8 in Port
Glasgow [0]). The old GPS traces will still have the old position, so
the majority (to start with) of traces are in the old place.

[0]
http://www.openstreetmap.org/?lat=55.937&lon=-4.697&zoom=16&layers=B0FT
-- 
Bruce Cowan <[EMAIL PROTECTED]>


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Re: [OSM-talk] OSM needs a measure for completeness

[Mark Williams]

Robert (Jamie) Munro wrote:
[]
> Rather than creating special ways, just to show completeness, why not
> mark the ways that are already there with weather or not they are
> completely connected. I.e. I know that all the roads and footpaths that
> connect to my road are on the map, so I could put a tag on the road
> saying complete_connected=roads,footpaths or something. We could then
> make a map with all the roads that are marked as not completed coloured.
> 
> Also, if we could make a tag for a road that you have seen one end of
> but haven't mapped down, that would be useful. Some people use 3
> unconnected nodes as a sort of ... symbol on the map, but this doesn't
> work very well. A short way that was tagged specially would indicate to
> people that that area needed surveying because the roads weren't
> complete. If a road had these for all the roads joining it, I would mark
> it as complete in the scheme above.
> 
> Robert (Jamie) Munro

Isn't that FIXME?

Validator picks this up especially (in JOSM) & highlights it.

I initially thought this was bad, but have just added it to all un-named
roads in 'my' area because an un-named road on my GPS looks, well, like
any other, but this tag shows up in my editor, on my GPS while I'm out -
and denotes a particular level of completeness. I have also used
note:TODO to mark a path end I'm not going down yet, because I can
search on it - but have swapped them for FIXME now.


The above 'Three Dots' would tend to pick up in Validator too, but with
a tempting 'Fix' button to unmark them ;)

Obviously this only applies to marking incompleteness, which is (as
previously observed) relatively simple... I think if all this gets to
proposals, I'd go for an 'incompleteness' markup which could include
things the mapper knows he hasn't done, + anything a script spots isn't
done, + any casual visitors observed needs, etc - any time an important
new feature comes up, it _could_ get added globally & removed progressively?

A 'complete' markup will go obsolete every time a vote gets approved &
can't cope with things we hadn't thought of at the time, and it's all
very well saying it's only for given parts but just look at highway
tagging for example - bus_guideway, turning_circle are in progress, and
will promptly render many 'streets complete' tags wrong if approved.

Mark


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Re: [OSM-talk] OSM needs a measure for completeness

[Robert (Jamie) Munro]

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Chris Morley wrote:
| David Earl wrote:
|  > I've said before and I'll say again: we need a way of
|  > asserting "this area is complete" (for one or more
|  > definitions of completeness).
|
| Andy Robinson (blackadder) wrote:
|  > The only way that we are going to individually or
|  > collectively state the completeness of a specific area
|  > is to carry out a verification process. It doesn't have
|  > to be done by third parties or even different contributors
|  > but it does need to be done by someone.
|  > We need a simple tag to display verification, perhaps
|  > the username and a date, say verification=blackadder_20080111
|  > or similar.
|
| Martin Trautmann wrote:
|  > Is OSM that far that we need verification and quality ensurance?
|  > We are still far from completeness, which might be a primary goal.
|
| I have started a new thread with a measure for completeness in the title
| because this is an important topic for OSM. But the response to the
| recent posts quoted above, and my raising of it last July, has been only
| luke-warm.

Rather than creating special ways, just to show completeness, why not
mark the ways that are already there with weather or not they are
completely connected. I.e. I know that all the roads and footpaths that
connect to my road are on the map, so I could put a tag on the road
saying complete_connected=roads,footpaths or something. We could then
make a map with all the roads that are marked as not completed coloured.

Also, if we could make a tag for a road that you have seen one end of
but haven't mapped down, that would be useful. Some people use 3
unconnected nodes as a sort of ... symbol on the map, but this doesn't
work very well. A short way that was tagged specially would indicate to
people that that area needed surveying because the roads weren't
complete. If a road had these for all the roads joining it, I would mark
it as complete in the scheme above.

Robert (Jamie) Munro
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Re: [OSM-talk] OSM needs a measure for completeness

[Tom Higgy]

Chris Morley wrote:
> OSM really needs a measure for local completeness to demonstrate its 
> progress externally. I hope enough people can be roused to discuss, and 
> hopefully agree, the principles, before deciding on an implementation.

Would it make any sense at all to consider it from the other angle, as 
in a measure of incompleteness, as well as completeness. That is make it 
easy for people to say 'there is a road missing here' or 'that's 
actually called hol demi close'? Then you verify these measures of in 
accuracy and the area is complete again.

I think it could work if there were enough people marking errors in a 
particular area, and would make it easier for those without the kit 
(i.e. GPS or aerial imagery) to get involved.

At the same time, of course, it would help to be able to say a 
particular user has verified this area to be complete at this particular 
point in time (changes happen, if you don't know when the area was 
marked complete you won't know a past development actually applies).
-- 
Cheers,

Tom
- www.bandnet.org

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Re: [OSM-talk] OSM needs a measure for completeness

[Tom Evans]

graham wrote:
> Surely completeness is relative to purpose? 

Sort of - I think you need definitions in terms of content rather than purpose, 
just for clarity.  But they could obviously be aimed at a purpose.

When I said 'multiple' definitions I definitely had in mind separately defined 
levels like Chris said below.  There might be a rough ordering, but nothing 
like 
a 1-5 scale.  If, in the future, somebody wants to add field boundaries, and 
somebody else thinks marking all the shops is more important, we don't want 
to argue over which goes in level 6!

Chris Morley wrote:

> They would be tagged with one (or possibly more) definitions of 
> completeness like "major roads", "public roads", "public paths", which 
> would be defined on a wiki page.



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Re: [OSM-talk] OSM needs a measure for completeness

[graham]

80n wrote:

> 
> In a sense I'm already doing this.  The very last thing I do when I've
> completed an area is to add landuse=residential (only where appropriate,
> of course).  I could easily add complete=level-n to this landuse boundary.
> 

Surely completeness is relative to purpose? I have areas where all roads
between settlements are filled in but not the settlements, other urban
areas where all roads are filled in and named, others where all roads
and footpaths are complete. I haven't yet done any areas which have
complete traffic lights, pedestrian crossings, turn restrictions, bus
routes, administrative boundaries, or navigational information for
waterways. The possible purposes are pretty orthogonal - rather than a
set of numbered completeness, you'd need to allow multiple
'complete_for=purpose' tags. And if you attach that to landuse
boundaries, what do you do in large urban areas where it's all residential?

Graham

> 80n
> 
> 
>  
> 
> 
> Chris
> 
> 
> 
> 
> 
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Re: [OSM-talk] OSM needs a measure for completeness

[Dair Grant]

Frederik Ramm wrote:

>>There are places in OSM where there is no data; these are
>>obviously incomplete.
>
>How would you know ;-) there are places which are complete with
>nothing on them!

Good point! Which makes it all the more important to have a 
mechanism for marking it as such, if only to reduce the number 
of people who make pointless trips to the middle of nowhere to 
confirm there's nothing there...


-dair (although given enough pointless trips, you would create a 
de-facto footpath - problem solved! ;-)
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Re: [OSM-talk] OSM needs a measure for completeness

[Frederik Ramm]

Hi,

> There are places in OSM where there is no data; these are 
> obviously incomplete.

How would you know ;-) there are places which are complete with
nothing on them!

Bye
Frederik

-- 
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Re: [OSM-talk] OSM needs a measure for completeness

[Frederik Ramm]

Hi,

> OSM really needs a measure for local completeness to demonstrate its 
> progress externally. I hope enough people can be roused to discuss, and 
> hopefully agree, the principles, before deciding on an implementation.

I'm all for it but I would really try to deduce this completeness from
external sources.

For example:

* Get statistics about paved roads in certain administrative areas,
  compare with OSM paved roads, arrive at a percentage of
  completeness.

* Get population statistics and a good estimate for length of roads
  or ways per capita in the type of area you're looking at; use that
  to compute how many miles of road you should have and compare to 
  OSM.

* Get number of named roads for certain areas (even if the full lists
  might be legally problematic, it should be possible to call someone
  in the city administration and ask them for the *number* of roads 
  at least!) and compare with OSM data.

And so on. This will of course never be accurate but could help to
draw coloured maps that give us an estimate of how good we're doing.

Self-assessed detail complenetess ("Personally went to this quarter
and verified every road") is something that I see further down the
road, and that will probably require some technical infrastructure.
Whereever possible I'd like to try and have this completeness assessed
by people *other* than those who did the mapping; maybe through a web
interface where casual visitors can check their area of residence and
rubber-stamp it (or note down complaints).

Bye
Frederik

-- 
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Re: [OSM-talk] OSM needs a measure for completeness

[Freek]

On Saturday 12 January 2008, Tom Evans wrote:
> David Earl wrote:
>  > I've said before and I'll say again: we need a way of
>  > asserting "this area is complete" (for one or more
>  > definitions of completeness).
>
> Chris Morley wrote:
> > A possible detailed approach is as follows. A completeness boundary
> > would be modelled on coastline: it would enclose an area, but would
> > consist of many (ordinary) ways, with the completed area on the right.
> > They would be tagged with one (or possibly more) definitions of
> > completeness like "major roads", "public roads", "public paths", which
> > would be defined on a wiki page. Boundary ways would be moved or added
> > on a day-to-day basis by anybody with local knowledge. An area might
> > even have holes in it.  Somebody would provide an overview map showing
> > completed areas, and its animation would feature in most presentations
> > on OSM.
>
> I like the idea, 

Me too.

> but agree it definitely needs the multiple (documented) 
> definitions of completeness. 

Apart from some linear scale (e.g. 1-5 as suggested), I think we might also 
need some more specific approach for the areas covered by the AND and TIGER 
imports. Both will perhaps score 5 on the completeness scale for roads, but 
for example AND imported data needs some work to get it "up to standard" [1]. 
Also, most tracks and cycleways are not present. It would be nice to be able 
to say that for some area that (e.g.)
- road data is from AND and partially verified;
- major tracks and unsurfaced roads are added;
- cycleways are complete;
- amenities are not added.

On the other hand, to be able to more easily render a nice map (overlay?) of 
completeness, it might be better to re-define the linear scale for these 
areas... (Which, I know, is perhaps not very nice.)

[1] http://wiki.openstreetmap.org/index.php/AND-NL:_Todo
Dutch todo list regarding data imported from AND. For example all ways not 
accessible by cars are tagged as highway=pedestrian. On a case-by-case basis 
this needs to be changed to e.g. footway, cycleway or left pedestrian.

-- 
Freek

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Re: [OSM-talk] OSM needs a measure for completeness

[Tom Evans]

David Earl wrote:
 > I've said before and I'll say again: we need a way of
 > asserting "this area is complete" (for one or more
 > definitions of completeness).

Chris Morley wrote:
> A possible detailed approach is as follows. A completeness boundary 
> would be modelled on coastline: it would enclose an area, but would 
> consist of many (ordinary) ways, with the completed area on the right. 
> They would be tagged with one (or possibly more) definitions of 
> completeness like "major roads", "public roads", "public paths", which 
> would be defined on a wiki page. Boundary ways would be moved or added 
> on a day-to-day basis by anybody with local knowledge. An area might 
> even have holes in it.  Somebody would provide an overview map showing 
> completed areas, and its animation would feature in most presentations 
> on OSM.

I like the idea, but agree it definitely needs the multiple (documented) 
definitions of completeness.  I'd personally like to reach an annotated map 
of all the footpaths to say what they're like, but this is silly  without 
getting 
the road coverage in an area first.

Also agree this should be be done before 'verification'.  But maybe the 
annotation for that could piggyback on the same system once it's tested 
and bugs ironed out.  The former would lead toward the latter, I would think. 
Particularly since you couldn't verify anything without a documented definition 
of the claimed completeness anyway.

Tom




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Re: [OSM-talk] OSM needs a measure for completeness

[Dair Grant]

Chris Morley wrote:

>I have started a new thread with a measure for completeness in the
>title because this is an important topic for OSM. But the response
>to the recent posts quoted above, and my raising of it last July,
>has been only luke-warm.

I also think completeness is a very important idea - it's false 
to think that a map is ever going to be "complete", but I don't 
think it's a good answer to say it can't be done.

There are places in OSM where there is no data; these are 
obviously incomplete.

Equally there are places in where the data is at least as good 
as any other map (bits of London say), subject to our data model 
(no house numbers, say).


>I wonder whether this is because "completeness" is associated in
>people's minds too closely with verification. As Andy has describes
>it in the (incomplete) quote above, verification involves individual
>accountability - "I personally accept responsibility for the
>accuracy of this data".

I don't think you accept responsibility for it in the sense of 
liability in case of mistakes, but as soon you as you enter some 
data into OSM you do accept some responsibility for it.

You're responsible for ensuring that it bears some relationship 
to reality, that it didn't come from an illegal source, etc.


>As is the case for all other mapping information, an assertion of
>completeness should only imply the best endeavours of the
>contributor, not a guarantee of 100% correctness. If you have ridden
>round a housing estate systematically and collected all the required
>information, you can reasonably say the area covered is complete.
>With this understanding, completeness would become part of routine
>mapping. It would encourage a systematic approach and the collection
>of any missed information.

Absolutely. I would be very happy if there was some way I could 
give a simple badge (or a score, 1-5, where 1 is empty and 5 is 
complete), to some area to indicate how "done" I thought it was.

Both to myself as a way to keep track of what's next, but also 
so that other mappers can see just how much there is to do.


>A possible detailed approach is as follows. A completeness boundary
>would be modelled on coastline: it would enclose an area, but would
>consist of many (ordinary) ways, with the completed area on the
>right. They would be tagged with one (or possibly more) definitions
>of completeness like "major roads", "public roads", "public paths",
>which would be defined on a wiki page. Boundary ways would be moved
>or added on a day-to-day basis by anybody with local knowledge. An
>area might even have holes in it.  Somebody would provide an
>overview map showing completed areas, and its animation would
>feature in most presentations on OSM.

I was thinking of a simpler model - each OSM account gets to 
define a list of bounding circles, and a 1-5 completeness rating 
for each circle.

Circles rather than boxes, because completeness is by definition 
a fuzzy subject.

Rather than trying to exactly cover the world with areas that 
are done/not done, it'd be better to just drop some approximate 
circles to cover smallish areas.


These will all overlap and generally look a bit of a mess, but I 
think could be rendered in a way that would give you a sense of 
completeness in some area and demonstrate progress.

E.g., at this point in time the areas that are complete should 
have more priority when rendering a zoomed out view - everyone 
knows that London will have lots of little holes in it, but in 
general most of the circles in there will be "complete".

When you zoom in then the incomplete areas become more 
important, so by the time you're at town/village level you want 
to be able to see which suburbs still need work to do.


The only difficult bit is setting up the database to manage this information.

I think it would be better done as part of the OSM user 
accounts, rather than in the OSM database, since I think putting 
it in the real data encourages us to try and over-specify 
something that's always going to be ambiguous.

Periodically some software pulls all that information out and 
renders a map of it, or sends a message to any users with 
obvious contradictions (two circles share more than 75% of their 
area and their ratings are too far apart, or similar).


-dair
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Re: [OSM-talk] OSM needs a measure for completeness

[80n]

On Jan 12, 2008 3:48 PM, Chris Morley <[EMAIL PROTECTED]> wrote:

> David Earl wrote:
>  > I've said before and I'll say again: we need a way of
>  > asserting "this area is complete" (for one or more
>  > definitions of completeness).
>
> Andy Robinson (blackadder) wrote:
>  > The only way that we are going to individually or
>  > collectively state the completeness of a specific area
>  > is to carry out a verification process. It doesn't have
>  > to be done by third parties or even different contributors
>  > but it does need to be done by someone.
>  > We need a simple tag to display verification, perhaps
>  > the username and a date, say verification=blackadder_20080111
>  > or similar.
>
> Martin Trautmann wrote:
>  > Is OSM that far that we need verification and quality ensurance?
>  > We are still far from completeness, which might be a primary goal.
>
> I have started a new thread with a measure for completeness in the title
> because this is an important topic for OSM. But the response to the
> recent posts quoted above, and my raising of it last July, has been only
> luke-warm.
>
> I wonder whether this is because "completeness" is associated in
> people's minds too closely with verification. As Andy has describes it
> in the (incomplete) quote above, verification involves individual
> accountability - "I personally accept responsibility for the accuracy of
> this data". I don't think this is suitable for OSM at the moment; it may
> be necessary in the future if and when OSM becomes a serious alternative
> to commercial suppliers - but not yet. I, and probably others, are eager
> to make their contributions of as high quality as possible, but are wary
> about making a public and personal commitment to their accuracy.
>
> As is the case for all other mapping information, an assertion of
> completeness should only imply the best endeavours of the contributor,
> not a guarantee of 100% correctness. If you have ridden round a housing
> estate systematically and collected all the required information, you
> can reasonably say the area covered is complete. With this
> understanding, completeness would become part of routine mapping. It
> would encourage a systematic approach and the collection of any missed
> information.
>
> A possible detailed approach is as follows. A completeness boundary
> would be modelled on coastline: it would enclose an area, but would
> consist of many (ordinary) ways, with the completed area on the right.
> They would be tagged with one (or possibly more) definitions of
> completeness like "major roads", "public roads", "public paths", which
> would be defined on a wiki page. Boundary ways would be moved or added
> on a day-to-day basis by anybody with local knowledge. An area might
> even have holes in it.  Somebody would provide an overview map showing
> completed areas, and its animation would feature in most presentations
> on OSM.
>
> OSM really needs a measure for local completeness to demonstrate its
> progress externally. I hope enough people can be roused to discuss, and
> hopefully agree, the principles, before deciding on an implementation.
>

In a sense I'm already doing this.  The very last thing I do when I've
completed an area is to add landuse=residential (only where appropriate, of
course).  I could easily add complete=level-n to this landuse boundary.

80n




>
> Chris
>
>
>
>
>
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[OSM-talk] OSM needs a measure for completeness

[Chris Morley]

David Earl wrote:
 > I've said before and I'll say again: we need a way of
 > asserting "this area is complete" (for one or more
 > definitions of completeness).

Andy Robinson (blackadder) wrote:
 > The only way that we are going to individually or
 > collectively state the completeness of a specific area
 > is to carry out a verification process. It doesn't have
 > to be done by third parties or even different contributors
 > but it does need to be done by someone.
 > We need a simple tag to display verification, perhaps
 > the username and a date, say verification=blackadder_20080111
 > or similar.

Martin Trautmann wrote:
 > Is OSM that far that we need verification and quality ensurance?
 > We are still far from completeness, which might be a primary goal.

I have started a new thread with a measure for completeness in the title 
because this is an important topic for OSM. But the response to the 
recent posts quoted above, and my raising of it last July, has been only 
luke-warm.

I wonder whether this is because "completeness" is associated in 
people's minds too closely with verification. As Andy has describes it 
in the (incomplete) quote above, verification involves individual 
accountability - "I personally accept responsibility for the accuracy of 
this data". I don't think this is suitable for OSM at the moment; it may 
be necessary in the future if and when OSM becomes a serious alternative 
to commercial suppliers - but not yet. I, and probably others, are eager 
to make their contributions of as high quality as possible, but are wary 
about making a public and personal commitment to their accuracy.

As is the case for all other mapping information, an assertion of 
completeness should only imply the best endeavours of the contributor, 
not a guarantee of 100% correctness. If you have ridden round a housing 
estate systematically and collected all the required information, you 
can reasonably say the area covered is complete. With this 
understanding, completeness would become part of routine mapping. It 
would encourage a systematic approach and the collection of any missed 
information.

A possible detailed approach is as follows. A completeness boundary 
would be modelled on coastline: it would enclose an area, but would 
consist of many (ordinary) ways, with the completed area on the right. 
They would be tagged with one (or possibly more) definitions of 
completeness like "major roads", "public roads", "public paths", which 
would be defined on a wiki page. Boundary ways would be moved or added 
on a day-to-day basis by anybody with local knowledge. An area might 
even have holes in it.  Somebody would provide an overview map showing 
completed areas, and its animation would feature in most presentations 
on OSM.

OSM really needs a measure for local completeness to demonstrate its 
progress externally. I hope enough people can be roused to discuss, and 
hopefully agree, the principles, before deciding on an implementation.

Chris





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