Add park layer

layers/park/class.sql

@@ -0,0 +1,7 @@
+CREATE OR REPLACE FUNCTION park_class(landuse TEXT, leisure TEXT, boundary TEXT) RETURNS TEXT AS $$
+    SELECT CASE
+        WHEN leisure = 'nature_reserve' OR boundary='national_park' THEN 'national_park'
+        WHEN landuse IN ('recreation_ground', 'village_green') or leisure = 'park' THEN 'public_park'
+         ELSE NULL
+     END;
+$$ LANGUAGE SQL IMMUTABLE;

layers/park/layer.sql

@@ -0,0 +1,46 @@
+-- etldoc: layer_park[shape=record fillcolor=lightpink, style="rounded,filled",
+-- etldoc:     label="layer_park |<z8> z8 |<z9> z9 |<z10> z10 |<z11> z11 |<z12> z12|<z13> z13|<z14_> z14_" ] ;
+
+CREATE OR REPLACE FUNCTION layer_park(bbox geometry, zoom_level int)
+RETURNS TABLE(osm_id bigint, geometry geometry, class text, subclass text) AS $$
+    SELECT osm_id, geometry,
+        park_class(landuse, leisure, boundary) AS class,
+        COALESCE(NULLIF(landuse, ''), NULLIF(leisure, ''), NULLIF(boundary, '')) AS subclass
+        FROM (
+        -- etldoc: osm_park_polygon_gen6 -> layer_park:z8
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen6
+        WHERE zoom_level = 8
+        UNION ALL
+        -- etldoc: osm_park_polygon_gen5 -> layer_park:z9
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen5
+        WHERE zoom_level = 9
+        UNION ALL
+        -- etldoc: osm_park_polygon_gen4 -> layer_park:z10
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen4
+        WHERE zoom_level = 10
+        UNION ALL
+        -- etldoc: osm_park_polygon_gen3 -> layer_park:z11
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen3
+        WHERE zoom_level = 11
+        UNION ALL
+        -- etldoc: osm_park_polygon_gen2 -> layer_park:z12
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen2
+        WHERE zoom_level = 12
+        UNION ALL
+        -- etldoc: osm_park_polygon_gen1 -> layer_park:z13
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon_gen1
+        WHERE zoom_level = 13
+        UNION ALL
+        -- etldoc: osm_park_polygon -> layer_park:z14
+        SELECT osm_id, geometry, landuse, leisure, boundary, NULL::int as scalerank
+        FROM osm_park_polygon
+        WHERE zoom_level >= 14
+    ) AS zoom_levels
+    WHERE geometry && bbox;
+$$ LANGUAGE SQL IMMUTABLE;

layers/park/mapping.yaml

@@ -0,0 +1,69 @@
+generalized_tables:
+
+  # etldoc: imposm3 -> osm_park_polygon_gen6
+  park_polygon_gen6:
+    source: park_polygon_gen5
+    sql_filter: area>15000000
+    tolerance: 300.0
+
+  # etldoc: imposm3 -> osm_park_polygon_gen5
+  park_polygon_gen5:
+    source: park_polygon_gen4
+    sql_filter: area>4200000
+    tolerance: 200.0
+
+  # etldoc: imposm3 -> osm_park_polygon_gen4
+  park_polygon_gen4:
+    source: park_polygon_gen3
+    sql_filter: area>1200000
+    tolerance: 120.0
+
+  # etldoc: imposm3 -> osm_park_polygon_gen3
+  park_polygon_gen3:
+    source: park_polygon_gen2
+    sql_filter: area>480000
+    tolerance: 80.0
+
+  # etldoc: imposm3 -> osm_park_polygon_gen2
+  park_polygon_gen2:
+    source: park_polygon_gen1
+    sql_filter: area>240000
+    tolerance: 50.0
+
+  # etldoc: imposm3 -> osm_park_polygon_gen1
+  park_polygon_gen1:
+    source: park_polygon
+    sql_filter: area>60000
+    tolerance: 20.0
+
+tables:
+
+  # etldoc: imposm3 -> osm_park_polygon
+  park_polygon:
+    type: polygon
+    fields:
+    - name: osm_id
+      type: id
+    - name: geometry
+      type: validated_geometry
+    - name: landuse
+      key: landuse
+      type: string
+    - name: leisure
+      key: leisure
+      type: string
+    - name: boundary
+      key: boundary
+      type: string
+    - name: area
+      type: pseudoarea
+    mapping:
+      landuse:
+      - park
+      - village_green
+      - recreation_ground
+      leisure:
+      - nature_reserve
+      - park
+      boundary:
+      - national_park

layers/park/park.yaml

@@ -0,0 +1,22 @@
+layer:
+  id: "park"
+  description: |
+      Landuse is used to describe use of land by humans.At lower zoom levels this is
+      from Natural Earth data for residential (urban) areas and at higher zoom levels mostly OSM `landuse` tags.
+  buffer_size: 4
+  fields:
+    class: |
+        More generalized groups of either `park`, `school`, `hospital`, `railway`,
+        `cemetery`, `military`, `residential`. Use this to assign general for landuse.
+    subclass: |
+        Original value of either the `amenity`, `landuse`, `leisure` or `boundary` tag.
+        Use this to do more precise styling.
+  datasource:
+    geometry_field: geometry
+    query: (SELECT geometry, class, subclass FROM layer_park(!bbox!, z(!scale_denominator!))) AS t
+schema:
+  - ./class.sql
+  - ./layer.sql
+datasources:
+  - type: imposm3
+    mapping_file: ./mapping.yaml

openmaptiles.yaml

@@ -12,6 +12,7 @@ tileset:
     - layers/water/water.yaml
     - layers/waterway/waterway.yaml
     - layers/landcover/landcover.yaml
+    - layers/park/park.yaml
     - layers/landuse/landuse.yaml
   name: OpenMapTiles v1.0
   description: "A tileset showcasing all layers in OpenMapTiles. http://openmaptiles.org"