Re: [Talk-GB] New users and P2

[ael]

On Fri, Feb 26, 2016 at 11:23:34AM +, David Woolley wrote:
> On 25/02/16 17:04, Nick Whitelegg wrote:
> 
> >User can also enter relevant POIs like stiles, gates etc when they are
> >encountered.
> 
> This might have been a good idea in the early days, when most mapping used
> GPS and most mapping was onto an empty map.  These days, I think it would
> just cause problems as it would probably delay the proper association of the
> GPS tracks with, more accurate, aerial imagery data, and would not properly
> account for features that had already been mapped, but possibly on a
> different, or more accurate datum.

While there are many pretty awful gps devices out there, some consumer
gps units can be fairly accurate if used with an understanding of the
technology. I am not happy with the suggestion that aerial imagery is 
more accurate for all the well known reasons of alignment and parallax.
I keep having armchair mappers fouling up accurately surveyed data
with near nonsense, and it is very demotivating.

I sometimes wonder if a source tag indicating some notion of accuracy 
would help, although I am not sure how that could be objective unless it
was using diffferential gps. But my experience of many armchair mappers
is that they just ride roughshod and ignore source tags and the like.
To be fair, the editors don't help with this, and it can be tedious and 
time consuming to review the history of everything before modification.

ael



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Re: [Talk-GB] New users and P2

[David Woolley]

On 26/02/16 12:44, Chris Hill wrote:

I disagree. GPS traces can only be found by being on the ground. Aerial
imagery is useful but being there and seeing what is really on the
ground is still the gold standard in my view. Aerial imagery is not
guaranteed to be well aligned, is guaranteed to be be steadily more and
more out of date and gives no clue about what signs say. Mapping by
surveying gives such a good understanding of what is really there that
it is the best way to integrate your new stuff and perhaps correct what
may have been added by the folks who have gone before.


The proposal appeared to be for a tool that only used the GPS traces and 
went straight from them to the database.  My point is that these days 
you need to integrate the GPS traces with the aerial imagery and with 
what is already mapped.


If you don't integrate with the aerial imagery, you will end up with a 
feature with large errors which won't get corrected for a long time 
because people will assume that they do account for all data sources.


If you don't integrate with existing features, you will end up with 
topological errors and possible duplication.


Whilst the GPS tagged ground survey is important, it needs to be 
integrated with the other sources and the only current way of doing that 
well involves the use of wetware and tools that show the other resources.


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Re: [Talk-GB] New users and P2

[Marc Gemis]

But a gate is some kind of important nagivational point.
I'm pretty sure that when someone removes a bench in my hometown, it
will take me a pretty long time to notice.

m

On Fri, Feb 26, 2016 at 1:42 PM, Andy Townsend  wrote:
> On 26/02/2016 07:59, Marc Gemis wrote:
>>
>> How do you detect that stuff is gone ? I'm thinking of benches,
>> waste-bins, telephones, etc. All those little things that are not or
>> hardly visible on aerial imagery ?
>> Do you constantly look at the screen of your smartphone or GPS to see
>> whether there is such a "small" thing mapped ?
>>
> The maps I use on both the phone and the Garmin try and make the sorts of
> small things that I'm interested in fairly obvious (on Garmin maps I use the
> Garmin Office "G" symbol for gates, for example, and the map I use on the
> phone goes up to z20 overzoomed to z21, so it's easy to see small details
> there too, and read the text on a small screen).
>
> I still end up marking that (e.g.) "there is a bus stop here" and getting
> home and finding that it's already mapped, though :)
>
> Cheers,
>
> Andy
>

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Re: [Talk-GB] New users and P2

[Chris Hill]

On 26/02/16 11:23, David Woolley wrote:

On 25/02/16 17:04, Nick Whitelegg wrote:





User can also enter relevant POIs like stiles, gates etc when they are
encountered.


When user returns home, track simplification algorithm used to make a
way from the GPX trace and tags it with the tags equivalent to the 
ROW type.



User downloads data from OSM and algorithms are used to auto-join the
user's new ways to existing ways where appropriate (or alternatively,
the user does this manually)


This might have been a good idea in the early days, when most mapping 
used GPS and most mapping was onto an empty map.  These days, I think 
it would just cause problems as it would probably delay the proper 
association of the GPS tracks with, more accurate, aerial imagery 
data, and would not properly account for features that had already 
been mapped, but possibly on a different, or more accurate datum.


I disagree. GPS traces can only be found by being on the ground. Aerial 
imagery is useful but being there and seeing what is really on the 
ground is still the gold standard in my view. Aerial imagery is not 
guaranteed to be well aligned, is guaranteed to be be steadily more and 
more out of date and gives no clue about what signs say. Mapping by 
surveying gives such a good understanding of what is really there that 
it is the best way to integrate your new stuff and perhaps correct what 
may have been added by the folks who have gone before.


--
Cheers, Chris (chillly)


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Re: [Talk-GB] New users and P2

[Andy Townsend]

On 26/02/2016 07:59, Marc Gemis wrote:

How do you detect that stuff is gone ? I'm thinking of benches,
waste-bins, telephones, etc. All those little things that are not or
hardly visible on aerial imagery ?
Do you constantly look at the screen of your smartphone or GPS to see
whether there is such a "small" thing mapped ?

The maps I use on both the phone and the Garmin try and make the sorts 
of small things that I'm interested in fairly obvious (on Garmin maps I 
use the Garmin Office "G" symbol for gates, for example, and the map I 
use on the phone goes up to z20 overzoomed to z21, so it's easy to see 
small details there too, and read the text on a small screen).


I still end up marking that (e.g.) "there is a bus stop here" and 
getting home and finding that it's already mapped, though :)


Cheers,

Andy


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Re: [Talk-GB] New users and P2

[Philip Barnes]

On Fri Feb 26 11:23:34 2016 GMT, David Woolley wrote:
> On 25/02/16 17:04, Nick Whitelegg wrote:
> >
> 
> > User can also enter relevant POIs like stiles, gates etc when they are
> > encountered.
> >
> >
> > When user returns home, track simplification algorithm used to make a
> > way from the GPX trace and tags it with the tags equivalent to the ROW type.
> >
> >
> > User downloads data from OSM and algorithms are used to auto-join the
> > user's new ways to existing ways where appropriate (or alternatively,
> > the user does this manually)
> 
> This might have been a good idea in the early days, when most mapping 
> used GPS and most mapping was onto an empty map.  These days, I think it 
> would just cause problems as it would probably delay the proper 
> association of the GPS tracks with, more accurate, aerial imagery data, 
> and would not properly account for features that had already been 
> mapped, but possibly on a different, or more accurate datum.
> 
PROW mapping still requires good gps traces, such mapping simply cannot be done 
using aerial imagery alone. 

Whilst my experienced countryside eye can spot a gate used by farm vehicles, 
there is no way to tell if a hedge/fence crossing in a stile,  gate or kissing 
gate without an on the ground survey. 

Any tools which help mapping these can only be a good thing. 

Phil (trigpoint)
-- 
Sent from my Jolla
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Re: [Talk-GB] New users and P2

[David Woolley]

On 25/02/16 17:04, Nick Whitelegg wrote:





User can also enter relevant POIs like stiles, gates etc when they are
encountered.


When user returns home, track simplification algorithm used to make a
way from the GPX trace and tags it with the tags equivalent to the ROW type.


User downloads data from OSM and algorithms are used to auto-join the
user's new ways to existing ways where appropriate (or alternatively,
the user does this manually)


This might have been a good idea in the early days, when most mapping 
used GPS and most mapping was onto an empty map.  These days, I think it 
would just cause problems as it would probably delay the proper 
association of the GPS tracks with, more accurate, aerial imagery data, 
and would not properly account for features that had already been 
mapped, but possibly on a different, or more accurate datum.



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Re: [Talk-GB] New users and P2

[Marc Gemis]

How do you detect that stuff is gone ? I'm thinking of benches,
waste-bins, telephones, etc. All those little things that are not or
hardly visible on aerial imagery ?
Do you constantly look at the screen of your smartphone or GPS to see
whether there is such a "small" thing mapped ?

regards

m

On Thu, Feb 25, 2016 at 6:28 PM, Andy Townsend  wrote:
> On 25/02/2016 17:04, Nick Whitelegg wrote:
>
>
> One thought I've had for a long time (and have probably mentioned in the
> past) is a walkers' editor (app rather than web-based). To be used something
> like:
>
>
> User goes for walk and records GPX trace, following this sort of pattern.
>
>
> Each time the type of right of way changes, the user selects a high level
> type ("Public Footpath", "Public Bridleway" etc in the UK) together with
> optional surface tags.
>
>
> User can also enter relevant POIs like stiles, gates etc when they are
> encountered.
>
>
> When user returns home, track simplification algorithm used to make a way
> from the GPX trace and tags it with the tags equivalent to the ROW type.
>
>
> User downloads data from OSM and algorithms are used to auto-join the user's
> new ways to existing ways where appropriate (or alternatively, the user does
> this manually)
>
>
> That's not a million miles from the way that I map right now, albeit without
> the benefits of an "app" as such:
>
> I record a GPS trace (on a Garmin) with numbered waypoints in it.  The
> symbols for the Garmin waypoints "mean" something, so the "boat ramp" symbol
> means "public right of way".  If it's a bridleway I'll add "BR" to the
> comment on the Garmin.  If more text is needed (e.g. the name of a shop I've
> created a waypoint for) I'll create an line in an email to myself, the start
> of which is the Garmin waypoint number and the rest of which is the comment.
>
> When I get home I'll split the individual traces out programmatically, merge
> the comments from the email into the GPX file (likewise) and upload to OSM.
>
> I'll then edit in OSM using the uploaded trace directly (using P2 - JOSM
> can't process waypoints in a way that's useful to me).  Usually the
> combination of new GPS trace, previous GPS traces, Bing imagery, OS OpenData
> StreetView imagery and my recollection is enough to figure out where the
> path should go, but none of those (unless there are really _lots_ of old GPS
> traces) are good enough on their own.
>
> On an introductory level, I can definitely see the benefits of something
> that can suggest to people "here are the other attributes of $thing that
> you've just added", like iD does, and like Kort does/used to do (see
> http://wiki.openstreetmap.org/wiki/Kort_Game ).
>
> Cheers,
>
> Andy
>
>
>
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