[Talk-ca] Some feedback on import quality in Toronto

[Yaro Shkvorets]

Having reviewed the changeset, here are my 2 cents. OsmCha link for
reference: https://osmcha.mapbox.com/changesets/66881357/

1) IMO squaring is not needed in most of those cases.
- You can see difference between square and non-square ONLY at high zoom
level. And even then, it's not visible to the naked eye. We are talking
about inches here.
- Sometimes squaring is plain wrong to be applied here. Even though you
paid very close attention you managed to square a couple of non-square
buildings. Like this facade is not supposed to be square for example:
https://i.imgur.com/H10360K.png I might be OK with squaring almost-square
angles if there is a simple plugin for that. The way you propose to do it,
by going building-by-building and pressing Q is completely unsustainable
and sometimes makes things bad.
- Another thing, this particular neighbourhood is pretty dense and mature
and therefore has mostly square buildings. I can only imagine how bad it
would become if you ask people to square things in newer developments where
buildings often come in irregular shapes.
- Like mentioned above, many successful import didn't require squaring. In
this Texas one, 100% of buildings are not perfectly square:
https://www.openstreetmap.org/#map=19/32.97102/-96.78231


2) Simplification is good to have, sure. Obviously standard Shift-Y in JOSM
is a no-starter. If we can find a good way to simplify ways without losing
original geometry and causing overlapping issues we should do it. But even
then, reducing 500MB province extract to 499MB should not be a hill to die
on.

3) Manually mapping all the sheds and garages is completely unsustainable.
Having seen over the last couple of years how much real interest there is
in doing actual work importing buildings in Canada (almost zero) adding
this requirement will undoubtedly kill the project. Sure you will
meticulously map your own neighbourhood, but who will map thousands of
other places with the same attention to details? Also, you did rather poor
job at classifying buildings you add, tagging them all with building=yes.
Properly classifying secondary buildings like sheds and garages in a
project like this is pretty important IMO. I agree with John, we should
leave sheds to local mappers to trace manually.

To sum up, yes we can do better. But this is the perfect example when
"better" is the enemy of "good".

On Sun, Feb 3, 2019 at 12:34 PM Nate Wessel <bike756 at gmail.com> wrote:

> Hi all,
>
> I had a chance this morning to work on cleaning up some of the
> already-imported data in Toronto. I wanted to be a little methodical about
> this, so I picked a single typical block near where I live. All the
> building data on this block came from the import and I did everything in
> one changeset: https://www.openstreetmap.org/changeset/66881357
>
> What I found was that:
>
> 1) Every single building needed squaring
>
> 2) Most buildings needed at least some simplification.
>
> 3) 42 buildings were missing.
>
> I knew going in that the first two would be an issue, but what really
> surprised me was just how many sheds had not been imported. There are only
> 53 houses on the block, but 42 sheds/garages/outbuildings, some of them
> quite large, and none of which had been mapped.
>
> I haven't seen the quality of the outbuildings in the source data, and
> maybe I would change my mind if I did, but I think if we're going to do
> this import properly, we're going to have to bring in the other half of the
> data. I had seen in the original import instructions that small buildings
> were being excluded - was there a reason for this?
>
> I also want to say: given how long it took me to clean up and properly
> remap this one block, I'll say again that the size of the import tasks is
> way, way, way too large. There is absolutely no way that someone could have
> carefully looked at and verified this data as it was going in. I just spent
> a half hour fixing up probably about one-hundredth of a task square.
>
> We can do better than this!
> --
> Nate Wessel
> Jack of all trades, Master of Geography, PhD candidate in Urban Planning
> NateWessel.com <http://natewessel.com>
>
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>


-- 
Best Regards,
          Yaro Shkvorets
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