OUTDATED: Add is_paved boolean for road layer features

[nvkelso]

Picking up from #1334.... There are lots of different surface values, some of which fall under the generic rubric of "paved" and others which don't. Let's add a generic is_paved boolean for road layer features.

Once we have the is_paved logic we should also revisit dropping surface at low zooms, see #1334.

In Mapzen's bike map theme for Walkabout we have to test a long list of surface values, it would be more convenient to know if something is paved or not. (There are also plans to do more with surface for a road focused theme.)

Here's how OSM.org cartography categories them:

CASE
    WHEN surface IN ('unpaved', 'compacted', 'dirt', 'earth', 'fine_gravel', 'grass',
        'grass_paver', 'gravel', 'ground', 'mud', 'pebblestone', 'salt', 'sand',
        'wood chips', 'clay') THEN 'unpaved'
    WHEN surface IN ('paved', 'asphalt', 'cobblestone', 'cobblestone:flattened',
        'sett', 'concrete', 'concrete:lanes', 'concrete:plates', 'paving_stones', 'metal',
        'wood') THEN 'paved'

Note: we don't use : in Tilezen property names or values so the following are re-mapped:

• cobblestone:flattened to cobblestone_flattened
• concrete:lanes to concrete_lanes
• concrete:plates to concrete_plates

[zerebubuth]

Would we default is_paved to true or false? Or different defaults for different road types (e.g: true for roads, false for tracks and paths)?

[nvkelso]

Generally we only export boolean values when true, so I see your point ;) Maybe we only export it when false?

(There's also a related concept here of warning people when a surface is impassable when wet for clay and related kind values, commonly seen in desert southwest of United States and Australian outback.)

Agree we should vary default by highway=* (and see related tracktype where only grade1 is assumed paved). We should probably do what Valhalla is doing. From the OSM wiki:

For roads for motor vehicles there there is normally an assumption that the surface is surface=paved unless otherwise stated. Paved in OpenStreetMap is non-specific and may cover sealed, tarmac, asphalt, bitumen. surface=unpaved is treated as the opposite of paved.

For Tangram we can test:

• filter: { is_paved: true } will match any feature with that property (any value)
• filter: { is_paved: false } will match any feature without that property
• filter: { is_paved: [true] } will only match feature with that property when value is true
• filter: { is_paved: [false] } will only match feature with that property when value is false

From TagInfo values with ≥ 0.01% &/or greater than 500 count.

sufrace	count	%	wiki	remapping
asphalt	6 752 489	38.40%	✔
unpaved	3 248 873	18.48%	✔
paved	2 333 886	13.27%	✔
ground	1 199 169	6.82%	✔
gravel	1 106 077	6.29%	✔
concrete	547 291	3.11%	✔
dirt	531 377	3.02%	✔
paving_stones	463 595	2.64%	✔
grass	444 335	2.53%	✔
compacted	214 843	1.22%	✔
sand	200 335	1.14%	✔
cobblestone	157 759	0.90%	✔
fine_gravel	57 193	0.33%	✔
wood	51 736	0.29%	✔
sett	39 743	0.23%	✔
earth	36 181	0.21%	✔
pebblestone	31 963	0.18%	✔
concrete:plates	31 844	0.18%	-	concrete_plates
mud	9 922	0.06%	✔
clay	9 731	0.06%	-
grass_paver	8 462	0.05%	✔
metal	7 915	0.05%	✔
concrete:lanes	7 472	0.04%	✔	concrete_lanes
paving_stones:30	6 180	0.04%	✔	paving_stones
tartan	5 915	0.03%	-
artificial_turf	4 397	0.03%	-
dirt/sand	3 971	0.02%	-	dirt_sand
cobblestone:flattened	3 815	0.02%	✔	cobblestone_flattened
asphalt␣no␣1	3 660	0.02%	-	asphalt ??
stone	3 143	0.02%	-
bricks	2 565	0.01%	-
hard	1 827	0.01%	-
cement	1 666	0.01%	-
rock	1 507	0.01%	-
interlock	1 498	0.01%	-
brick	1 270	0.01%	-
ground;grass	1 235	0.01%	-	ground ??
rocky	1 223	0.01%	-
soil	1 031	0.01%	-
asphalt␣no␣1	3 660	0.02%	-	asphalt ??
grass;earth	832	0.00%	-	grass ??
woodchips	807	0.00%	-
pebbles	644	0.00%	-
gravel;ground	633	0.00%	-	gravel ??
granite	618	0.00%	-
limerock	610	0.00%	-
laterite	570	0.00%	-
grass;ground	557	0.00%	-	grass ??
asphalt␣deg␣2	524	0.00%		asphalt ??
metal_grid	513	0.00%	-
shells	506	0.00%	-

NOTE: ␣ is used to represent a space character.

[matkoniecz]

cobblestone:flattened is not transformed at this moment, I filed #1337 to correct this

[matkoniecz]

paving_stones:30

Maybe it would be better to ignore this values? 6k usages is not significant and maybe encouraging using sensible surface values overall would have a better effect?

Note that is used to (it seems) to marking paving stones as ones with size of 30cm. Encouraging to use it means encouraging to use separate surface value for every size of paving stone.

[matkoniecz]

Or different defaults for different road types (e.g: true for roads, false for tracks and paths)?

Location (is given way inside park/forest etc) is already computed, maybe set highway=path/footway default depending on location?

For example unpaved as default in forests, paved as default in urban areas?

[nvkelso]

Maybe it would be better to ignore this values (nvk: of paving_stones:30)? 6k usages is not significant and maybe encouraging using sensible surface values overall would have a better effect?

I'm fine remapping it to paving_stones. I've updated the table.

[nvkelso]

Location (is given way inside park/forest etc) is already computed, maybe set highway=path/footway default depending on location?
For example unpaved as default in forests, paved as default in urban areas?

👍 That's a great idea!

This would require queries.yaml to do the landuse_kind intercut before we calculate the is_paved value.

[nvkelso]

Moving in to the v1.6 milestone as I think it should be marked process changed with what @zerebubuth proposes in #1710 (comment).

[nvkelso]

Process changed to #1716.