Add landuse kind to buildings

[nvkelso]

Like we are planning for roads: #136

[rmarianski]

This one might be a little bit trickier, because currently we don't clip buildings. If a building is completely contained within a landuse polygon it's fine, but if it's just a portion of it, what should we do?

[nvkelso]

Thinking out loud:

• If 100% of a building is contained within a landuse polygon, do get the landuse attribute.
• If 80% of a building is contained within a landuse polygon, do get the landuse attribute.
• If 60% of a building is contained within a landuse polygon, don't get the landuse attribute.
• If 10% of a building is contained within a landuse polygon, don't get the landuse attribute.

80% seems like a good fuzzy containment. The linework can be a little squishy (not line up perfect) but it'll still match. What do you think?

How does this work for buildings that extend past tile edges? We only know post processing for the part in the tile that has overlap with landuse? Do we attempt to resolve the whole shape?

[rmarianski]

80% seems like a good fuzzy containment. The linework can be a little squishy (not line up perfect) but it'll still match. What do you think?

Sounds reasonable to me.

How does this work for buildings that extend past tile edges? We only know post processing for the part in the tile that has overlap with landuse? Do we attempt to resolve the whole shape?

Yes, I was assuming that we would use the whole shape.

[zerebubuth]

I couldn't seem to get this to work / display properly in "skin-and-bones", but here's an example showing it in "simple-demo". Before:

After tilezen/TileStache#45:

Note that the purple buildings are theatres, even when they're in the park, because we're pulling in the building polygon as an "amenity" landuse. To me, this seems a bit weird, and we might want to see if we can be a bit more precise about what "landuse" actually means.

The scene file fragment for the above is:

    buildings:
        data: { source: osm }
        draw:
            polygons:
                order: 6
                color: '#404040'
        in_park:
          filter: { landuse_kind: park }
          draw:
            polygons:
              color: '#608040'
        in_garden:
          filter: { landuse_kind: garden }
          draw:
            polygons:
              color: '#408060'
        in_residential:
          filter: { landuse_kind: residential }
          draw:
            polygons:
              color: '#606070'
        in_theatre:
          filter: { landuse_kind: theatre }
          draw:
            polygons:
              color: '#804060'

[zerebubuth]

I should have made a note: we can prioritise the landuse values for intersection, which might be a work-around if we wanted the theatre to have landuse_kind: park instead.

[zerebubuth]

@nvkelso, how does it look?

[nvkelso]

Cool!

About the theaters:

• Feature properties: if the building's amenity tag is theatre than it should be export as kind: theatre (just the same as the address discussion, we should collapse the variety of "landuse" like tags into a single kind property on export).
• Intercut properties: If it's also in a park, then the exported building features should additionally get landuse_kind: park.

(Edited the feature properties bit to be less confusing)

[zerebubuth]

@nvkelso The theatre is already exported as a landuse area - that's why the building is detecting it and setting its landuse_kind: theatre. In general, we should be tie-breaking on the order parameter of the landuse.

Let's consider the case when we have a building inside an apron inside an aerodrome inside a farmland polygon inside a conservation polygon inside a rural polygon (I know much of that doesn't make sense in the real world... but bear with me).

What landuse should that building get, and what sort order should theatre get?

If it's "largest draws last", then theatre "landuse" will get applied to the theatre always, which isn't very useful. If it's anything other than that, then it won't represent what's actually underneath it, because there could be many other layers in between (e.g: between rural & apron).

I think the fix here is to stop pulling amenties which are buildings into the "landuse" layer.

[nvkelso]

Let's track the weirdness around buildings ending up in the landuse layer with: #201 and call this work done.

[nvkelso]

All PR have been merged.