[Talk-ca] Importing buildings in Canada

Wed Jan 15 20:54:20 UTC 2020

Hi John, Tim, and the others :-)
John, I understand your concern and if it was not addressed properly, this could block the import again.

IMHO, we just need to make sure that we have done everything reasonable to inform the concerned contributors, in order to discuss the import in case they do not agree with it. That is why I proposed the following, in a previous email, concerning local mappers buy-in…

1- We contact them to explain our intentions by referring to the appropriate wiki pages.
2- We wait a week or two for them to respond to nothing, have concerns or want to help.
3- Without negative answers, we could proceed to the import.

The point 3 above make sure the project is not stalled in case there is no or only a few answers. The identification of local contributors using Neis’ tool, or the query Tim Elrick just proposed, are what I consider reasonable attempts for contacting the local mappers.

Daniel

-----Original Message-----
From: Tim Elrick via Talk-ca [mailto:talk-ca at openstreetmap.org] 
Sent: Wednesday, January 15, 2020 15:12
To: talk-ca at openstreetmap.org
Subject: Re: [Talk-ca] Importing buildings in Canada

Hi all,

*a) data hosting*
I can offer to host pre-processed data for the building imports as well.

*b) task manager work units*
I find smaller tasks about 20 minutes each more appealing than 1 hour tasks

*c) checking already existing data*
An added tag would certainly help as you can apply a filter in JOSM then.

*d) finding local mappers*
You can use the following query on http://overpass-turbo.eu/ to get a 
list of all users in the time period specified in the area specified.

// overpass query
[out:csv(::user)];
// replace Montreal by any known location in OSM, or see code below
// for bounding box use
{{geocodeArea:Montreal}}->.searchArea;
(
   // I collected users active in the last 6 months, but you can
   // change that
   node(newer:"{{date:6 months}}")(area.searchArea);
   way(newer:"{{date:6 months}}")(area.searchArea);
   relation(newer:"{{date:6 months}}")(area.searchArea);
);
out meta;
// end overpass query

Copy the query into the left side of the window and click Export, then 
'raw data directly from Overpass API'. This will generate a csv. You can 
then count the number of times a name appears in your list by using 
LibreOffice, R, Python or Excel. This will give you the number of 
objects a user entered in the last 6 months.

If I do this for Montreal I end up with 106 names who have contributed 
20 objects or more in the last half year or 46 names who have 
contributed 100 objects and more.

You can then use https://www.openstreetmap.org/message/new/USERNAME by 
replacing USERNAME with the names from the list to contact these users.

For areas where there is no geocodeArea in OSM you can use the 
boundingbox query below. First, zoom to the area of interest (i.e. your 
bounding box), then paste the following code on the left and export:

// overpass query
[out:csv(::user)];
(
   node(newer:"{{date:6 months}}")({{bbox}});
   way(newer:"{{date:6 months}}")({{bbox}});
   relation(newer:"{{date:6 months}}")({{bbox}});
);
out meta;
// end overpass query

Tim

On 2020-01-15 12:55, Daniel @jfd553 wrote:
Thanks for the quick replies!

Now, about...

*a) Data hosting:*

Thank you James, I really appreciate your offer (and that of others). So
yes, I think hosting pre-processed data in the task manager, for
approved regions, is an attractive offer. When we agree on a
municipality for pre-processing, I will contact you to make the data
available.

BTW, I thought ODB data in OSM format was hosted with the OSMCanada task
manager. I understand that ODB data are currently converted on the fly
when requested?

*b) Task manager work units for import:*

I agree with Nate, ~ 200 buildings or ~ 1,500 nodes would be suitable. I
was thinking at the same importation rate, but for an hour of work. It
seems best to target 20-minute tasks.

*c) Task manager work units for checking already imported data*

According to Nate, it is definitely not faster than actively importing.
We should then keep the above setup (b).

However, what if I add a new tag to pre-processed data indicating if a
building was altered or not by the orthogonalization (and
simplification) process? For instance, /building:altered=no/, would
identify buildings that were not changed by the process and that could
be left unchanged in OSM (i.e. not imported); /building:altered=yes/ for
those who were changed by the process and that should be imported again.
The same pre-processed datasets could then be made available for all
cases. Thoughts?

*d) Finding local mappers:*

I agree with Nate’s suggestion to try contacting the top 10 mappers in
an area. Using the "main activity center" would work for most of the
contributors but selecting other overlays (.e.g. an activity center over
last 6 months) could also work great. As long as we identify who might
be interested in knowing there is an import coming.

Comments are welcome, particularly about the proposal on c)

Daniel

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