[HOT] Broken (multi)polygon cleanup

Jochen Topf jochen at remote.org
Sat Mar 18 10:20:56 UTC 2017

On Fri, Mar 17, 2017 at 10:48:00AM -0400, john whelan wrote:
> I've read it through but remember like many mappers I do not have a Ph.D.
> in GIS, just a degree in Chemistry so I'm usually not too bad on logic.
> The first thing that stands out is the message is too complex for the
> intended audience.

Yes, and no. The documentation we have now is trying to be complete and
thorough. The intended audience are, first, power mappers. I am totally
aware that it is too much for the average mapper, but that's why I need
everybodies help not only the fix things, but also to translate the
problem into words that the different audiences can understand.

I know that HOT has capable mappers that understand OSM well and have
written documentation for new HOT mappers to use. I hope I can reach
those people here so they can help.

> The second "The *new style* tagging option is the recommended tagging
> option these days, but some mappers still disagree."  So we don't have
> complete agreement, fine.

Well, that was me being overcautious. I haven't heard any disagreements
in the last months. So I don't think there is any major disagreements
left. I have removed that sentence from the documentation.

> The third is the main problem areas seem to be some rendering systems
> prefer one method over the other.  "Are we mapping for a specific rendering
> system now?"

No, we are not. I am not sure why you got that impression from the
documentation. Can you point me to a specific sentence? I have
highlighted Osm2pgsql, because it is by far the most often used basis
for rendering maps and it is what powers the main OSM map. So changes
there will affect more people. And it also means that basically every
other system is trying to mimic what Osm2pgsql is doing (right or
wrong), because they have to keep "in sync" with the main map that OSM
mappers use to verify their work.

Currently all rendering systems have to handle old- and new-style
multipolygons and in the future they wont have to do that any more. This
makes all systems simpler.

> I suspect if we concentrate on unclosed ways and duplicate segments then
> this is something that can be done without a Ph.D. in GIS concepts and
> there is no disagreement.  Leave the more complex problem solving to others.

I totally agree. That's why I have been splitting up the work into small
Maproulette tasks, each with a very easy to understand and concrete
description of what the fixing task is. I don't expect most mappers to
be able to solve complex multipolygon cases. But there are plenty of
simple cases around.

> I would recommend if you wish to use the resources of HOT that you talk
> nicely to the HOT training group and see if they can sort out the message
> and what training needs to be given to support these efforts including what
> you would like mappers to avoid when mapping.

I am hoping these people are listening here. (Are you?) Or do I have to
go somewhere else to talk to them?

Jochen Topf  jochen at remote.org  https://www.jochentopf.com/  +49-351-31778688

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