Inconsistency between Natural Earth and OSM road classes

[nvkelso]

I think the general kind: highway part of this was intentional, but possibly not the type: Major Highway > kind: highway. Generally speaking that should have gotten kind: major_road, kind_detail: trunk.

• https://github.com/tilezen/vector-datasource/blob/master/yaml/roads.yaml#L139-L148

  - filter:
      scalerank: true
      featurecla: Road
      type: [Major Highway, Beltway, Bypass]
    min_zoom: scalerank
    table: ne
    output:
      <<: *ne_properties
      kind: highway
      kind_detail: trunk

[zerebubuth]

Just to be sure I've understood this correctly: We want the input features with type Major Highway to result in output features with kind: major_road? This is kinda confusing, since "major highway" does suggest a highway.

Should we also remove the kind_detail: trunk from the Beltway and Bypass output (assuming they're keeping the kind: highway)?

[nvkelso]

The intent was to better match the motorway versus trunk "highway" transition between zoom 7 and 8 and OSM and Natural Earth (see images and link below).

But you're right – we need to ALSO combine this with Natural Earth's expressway = 1 tag to get the desired effect. Good catch!

So something more like this (assuming we import the expressway boolean from NE)?

  - filter:
      scalerank: true
      featurecla: Road
      type: Major Highway
      expressway: 1
    min_zoom: scalerank
    table: ne
    output:
      <<: *ne_properties
      kind: highway
      kind_detail: motorway
  - filter:
      scalerank: true
      featurecla: Road
      type: [Beltway, Bypass]
      expressway: 1
    min_zoom: scalerank
    table: ne
    output:
      <<: *ne_properties
      kind: highway
      kind_detail: motorway
  - filter:
      scalerank: true
      featurecla: Road
      type: Major Highway
    min_zoom: scalerank
    table: ne
    output:
      <<: *ne_properties
      kind: major_road
      kind_detail: trunk
  - filter:
      scalerank: true
      featurecla: Road
      type: [Beltway, Bypass]
    min_zoom: scalerank
    table: ne
    output:
      <<: *ne_properties
      kind: major_road
      kind_detail: trunk

Here's a view of northern California:

http://tangrams.github.io/bubble-wrap/#8/39.637/-123.054

[zerebubuth]

It looks like we already do pay attention to expressway:

vector-datasource/yaml/roads.yaml

Lines 215 to 244 in 68ad88a

	- filter:
	scalerank: true
	featurecla: Road
	expressway: 1
	min_zoom: { clamp: { min: 5, max: 17, value: { col: scalerank } } }
	table: ne
	output:
	<<: *ne_properties
	kind: highway
	kind_detail: motorway
	- filter:
	scalerank: true
	featurecla: Road
	type: [Major Highway, Beltway, Bypass]
	min_zoom: { clamp: { min: 5, max: 17, value: { col: scalerank } } }
	table: ne
	output:
	<<: *ne_properties
	kind: highway
	kind_detail: trunk
	- filter:
	scalerank: true
	featurecla: Road
	type: Secondary Highway
	min_zoom: { clamp: { min: 5, max: 17, value: { col: scalerank } } }
	table: ne
	output:
	<<: *ne_properties
	kind: major_road
	kind_detail: primary

Roughly translated, this is saying:

1. If expressway is 1, then kind is highway,
2. Else if type is one of Major Highway, Beltway or Bypass then kind is major_road with kind_detail trunk,
3. Else if type is Secondary Highway then kind is major_road with kind_detail primary.

As far as I can tell, this is essentially the same as the existing algorithm. Although there are 9 expressway Road and 164 expressway Secondary Highway in the database, I don't think any of them are in the view we're looking at.

For more detail: Here's some screenshots of OSM/NE in this location, mapping highways to red, major roads to blue (darker for kind_detail trunk, lighter and thinner for primary).

(Note that I've applied the appropriate scalerank filter, which is why the NE view has a more zoom-appropriate selection of roads than the OSM view - shouldn't affect the comparison between the data where we've got both.)

OSM

NE

Comparison

[nvkelso]

Yes, single line change in https://github.com/tilezen/vector-datasource/blob/master/yaml/roads.yaml#L233 from:

 kind: highway

to:

 kind: major_road

[nvkelso]

Accomplished: