[mkgmap-dev] Test cases for possible is-in-hook

Sat Dec 21 12:38:54 GMT 2019

Hi Gerd

This is looking more and more complicated with:
1/ High cost of total accuracy
2/ Multi-polygons haven't been processed at the time the hook attempts
to set the tag?
3/ holes due to multi-polygons
4/ lines crossing polygon boundaries where different attribute are
required on either side
5/ some uses of this feature might not want total accuracy, just
something close by.

What do you think of the idea of making this a style function?
1/ The cost can be delayed until the rule is evaluated
2/ Following on from this, if the requirement is only testing, say, a
way being in a polygon, the unnecessary work of calculating is-in for
all polygons and points is avoided 
3/ The function invoked from a rule itself can indicate, with a
parameter, what sort of algorithm/accuracy is required
4/ multi-polygon processing has happened at this point (has it?)

Thinking about total accuracy for polygons, if there was a function
that subtracts a polygon from another, then the change in area will
give the answer about full/partial/no inclusion.

Ticker 

On Sat, 2019-12-21 at 09:02 +0000, Gerd Petermann wrote:
> Hi all,
> 
> this is a follow up of http://gis.19327.n8.nabble.com/Commit-r4398-re
> vert-changes-from-r4397-is-in-landuse-option-tp5953750p5954041.html
> Attached is a new file which contains additional ways w28 .. w30 and
> w26 was changed from expected="?" to "in".
> The new ways are all very close to the residential polygon(s), but
> completely outside. 
> I think w26 and w30 show very common cases in OSM. Some mappers
> prefer to "glue" landuse polygons to highways, others don't. There
> are probably good reasons for both methods. Because of the poor
> precision the current code in mkgmap adds mkgmap:residential to both
> of them. See 
> http://gis.19327.n8.nabble.com/is-in-filter-tp5890564p5890566.html
> where Carlos stated that this would be welcomed (at least if the ways
> were e.g. highway=secondary instead of footway).
> If I change the code to be a lot more precise w30 would not be
> tagged. 
> On the other hand, if you ask for landuse=cemetery you probably don't
> want to change a cycleway next to it.
> Any ideas how to handle this dilemma? 
> 
> Gerd
> 
> P.S. In my hometown the cemetery expanded during the years and it now
> stretches across a residential road "Lehmkuhlenweg".  
> See https://www.openstreetmap.org/way/11760536
> I think in reality the cemetery is split into two parts, there are
> gates on the footways and barrier=fence or barrier=hedges along the
> road, but nobody mapped them until now.
> 
> 
> 
> 
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev