[Talk-ca] Mapping buildings in Canada by 2020
Tim Elrick
osm at elrick.de
Thu Nov 23 15:45:13 UTC 2017
There are in fact, quite some German based mappers, mapping in Canada.
So, you are right: let's just get more active mappers - worldwide; it
is, however, still easier to activate them locally.
I will pass on your positive experience with JOSM to my group for the
next event.
Cheers, Tim
Am 23.11.2017 um 10:32 schrieb john whelan:
>>I would have to run a query now to find out if the relative number of
active mappers is higher in one country than the other, but that's not
my point.
But how do you determine where a mapper lives and don't forget many
armchair mappers map in a different location to where they live.
JOSM and the building_tool plugin worked very well for our lot. We did
ask them to come with JAVA installed and we only taught them enough JOSM
to map a building with the plugin. Well we showed them a few more
things as they got more comfortable with it.
Cheerio John
On 23 November 2017 at 10:26, Tim Elrick <osm at elrick.de
<mailto:osm at elrick.de>> wrote:
Hi John,
Thanks for your feedback and background information.
I think, we are on the same page. I am concerned with quality too, while
mapping should remain enjoyable.
We shied away from JOSM for newbies because it seemed more technical to
my groups members. I personally like JOSM better, and the building
plug-in is great. Maybe I manage to convince the group to use it
next time.
I did not intend to call for experienced mappers to do all the
validation (I know it is tedious; however, correcting and esp. updating
makes OSM great and in some place much better than the official
sources). I think, that the group who initiated the mapping should
'clean up after themselves' (and I just wanted to affirm that we will do
that). I just wanted to express gratitude to mappers how do help out.
Once I am more into it, I am happy to help out validating other's work.
I did not mean to cheery pick when I quoted the validation website (I
very much appreciate the wiki page). I just wanted to make a point about
timing.
Regarding Canada, as a geographer I am fully aware of the fact Canada
having relatively less population, however, it has still almost half of
the population of Germany and the urban areas, which most of OSM mappers
are concerned with, might be relatively (to population) similar in size
(that's just a guess). I would have to run a query now to find out if
the relative number of active mappers is higher in one country than the
other, but that's not my point. The relative numbers do not matter, as
actual people do the mapping. And there, I hope we agree, the Canadian
OSM community could do with more active mappers.
Tim
Am 23.11.2017 um 07:54 schrieb john whelan:
The issue is the quality of the mapping, nothing else. I attended one of
these geoweek events and we used JOSM with the building_tool plugin.
The mapping of buildings was accurate even though 75% of the mappers had
never used JOSM before. There was no formal validation done but I
verified each mappers work as they did it. I got the impression that
the mappers enjoyed the exercise and I think for me that was the most
important thing. Mapping should be fun.
There was no mention of the work would be validated nor did we record
the mappers userids to ensure which mappers had mapped. Other mappers
had marked tiles done on the grid.
I was under the impression that Stats Canada was involved but was later
assured by them that this was not the case.
The problem of lots of new mappers producing low quality work really
reared its head during the Nepal crisis. I do mainly validation on HOT
projects in Africa and I ended up pulling in chunks of Africa and just
trying to clean up the map. Currently I'm looking at one mapper who has
added more than a thousand ways with one tag I think it says
source=PGS. Data quality is a major issue in OpenStreetMap. Recently
someone gave up when looking for area=yes or buildings drawn in iD but
left untagged for the most part. I think in Europe it was 100,000 or
more worldwide it was far higher and that's when the person looking at
it gave up.
There are many examples in Africa of groups of buildings being mapped as
one building and labelled building=house. That's what we are trying to
avoid. It is possible to correctly map a building in iD I've seen it
done but it takes time. It is far easier to sort of roughly get it
right and roughly means not accurately. I think the thing we need to
avoid is a feeling the mapper needs to get a tile done. That's when they
start to rush things.
Building validation? I can think of no validator who enjoys having to
take two or three times longer to correct someones's work than it would
take them to map it in JOSM with the building_tool in the first place.
I'm unable to even think of a case where a project has been validated
and the buildings corrected. When I validate I'm trying to correct the
mapper's work and give them feedback so they will map more accurately in
future. There is no point in doing this to someone who will map once.
It's a waste of my time.
The wiki page you pointed to, I wrote much of it. the most important
part which you skipped is feedback from a user.
Why do we validate?
“OpenStreetMap is often the only source of maps, but the data quality is
very uneven. I wish they’d put their more experienced mappers onto
validation.” This is a quote from an individual who used OpenStreetMap
data (HOT) in the field.
Note the comment the data quality is very uneven and that's what we are
trying to address. Your particular maperthon may have produced good
work, my lot certainly did but many mappers using the tag did not and
that is the issue.
By the way we do have fewer mappers per square kilometre than Germany
does and we have used CANVEC data to get a basic road network in. In
Ottawa we've used Open Data to bring in the bus stops. The basic
Canadian map isn't bad but if we had as many mappers per square
kilometre as Germany does then no doubt it would be better. Our
population density is also lower by the way if you hadn't noticed.
Cheerio John
On 22 November 2017 at 21:28, Tim Elrick <osm at elrick.de
<mailto:osm at elrick.de>
<mailto:osm at elrick.de <mailto:osm at elrick.de>>> wrote:
Hello all,
As you know Open Mapping Group McGill (OMG McGill) organized one
of the
mapathons last week for the town of Williams Lake, BC. For the
turnout
please turn to Julia's website published earlier today on the list.
As a mentor of the group I might be the 'director' of this event
according to the proposed policy by the OSMF board. In this
role, I want
to assure you that we tried to do our best to teach new mappers
how to
do their job properly, as Charles stated on this list yesterday. And
judging from a preliminary analysis of the data I conducted with the
overpass api, the participants did a pretty good job.
Of course, the data needs validation, which we will conduct in
the next
couple of days. However, I do not see the rush proposed on this list
earlier. Ideally, validation would happen right after the
mapping event
(as set out in this manual for HOT tasks [1]). In the real
world, we all
have our jobs, families and other voluntary engagements, that
sometimes
do not allow to act accordingly. I further think it is not even
necessary for tasks that are not related to immediate disaster
response
or include ways tagged with a highway tag (in the later case it
might
confuse navigation apps if not validated right away). In many cases,
validation, or better, correction of data entered by individual
mappers
(not part of group events) was (and still is) done many days or even
months after the data was entered, depending on whether an
experienced
mapper has an eye on a certain region or not. With regards to
buildings
in areas where there existed no respective data before, I do not
see any
need for rushing.
The important thing is that the organiser of a group event makes
sure
that the data entered by participants of the event *is* validated to
ensure data quality. And we will. To this end, I appreciate that
long-term members already offered to help us there (thank you,
Charles!).
I still consider mapathons a legitimate way to draw attention to
OSM, to
advocate for open data, and to show the potential of OSM data
and the
lack thereof in many parts of the world, including Canada. From the
experience of our first mapathon I got the impression that we
instigated
a vast interest in open mapping (which, I think, is a valid goal
on its
own right) and I expect quite a couple of returning participants
to our
next events, in which we will train them further on the
complexities to
produce good OSM data. By continuing, we might be able to
motivate one
or two persons to turn into long-term mappers; this is, by the way,
totally in line with the long-tail phenomenon researchers found
in all
crowd-sourcing projects.
All those reasons I mentionend, are, I think, worth it
continuing doing
what we did. I would appreciate, if the attitude towards group
mapping
events were less hostile on this list and on OSM as such (I am
aware of
less fortunate attempts conducting group mapping events
recently; but
try not blame them, but give them a hand to do it better next
time - and
I know you did, but some of them apparently did not understand how
communication works in OSM). Try to give them the benefit of the
doubt:
most mappers, even in group event, do this voluntarily and
because they
want to enjoy extend this great geodatabase!
IMHO, OSM cannot do without those events, because we do not want to
leave the future of OSM only to businesses and their paid
mappers (and
we have seen that in some countries, including Canada, there
might not
be enough people who find their way to OSM without those events).
Tim
[1]
http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/Validating_data#When_do_we_validate.3F
<http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/Validating_data#When_do_we_validate.3F>
<http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/Validating_data#When_do_we_validate.3F
<http://wiki.openstreetmap.org/wiki/OSM_Tasking_Manager/Validating_data#When_do_we_validate.3F>>
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