Revamp water label display logic (#1457)

* At zooms 9-13, water labels will now be rendered for water features that are at least 0.25 tiles in size.  This means that water features that are the same size as a 128x128 pixel square will get a point label.
* Labels for large water features are now shown at the lowest zoom at which it's appropriate to show a label.
* Bay and strait names (`natural=bay` and `natural=strait`) are included. 
* Large seas modeled as areas (e.g. Caspian Sea) render as `class=sea` rather than `class=lake`

layers/water/mapping.yaml

@@ -66,6 +66,9 @@ tables:
       type: string
     - name: tags
       type: hstore_tags
+    - name: place
+      key: place
+      type: string
     - name: natural
       key: natural
       type: string

layers/water_name/mapping.yaml

@@ -21,6 +21,9 @@ tables:
     - name: place
       key: place
       type: string
+    - name: natural
+      key: natural
+      type: string
     - name: rank
       key: rank
       type: integer
@@ -34,3 +37,6 @@ tables:
       place:
       - ocean
       - sea
+      natural:
+      - bay
+      - strait

layers/water_name/update_water_point.sql

@@ -2,14 +2,22 @@ DROP TRIGGER IF EXISTS trigger_delete_point ON osm_water_polygon;
 DROP TRIGGER IF EXISTS trigger_update_point ON osm_water_polygon;
 DROP TRIGGER IF EXISTS trigger_insert_point ON osm_water_polygon;
 
+-- etldoc:  osm_water_polygon ->  osm_water_point_view
+-- etldoc:  lake_centerline ->  osm_water_point_view
 CREATE OR REPLACE VIEW osm_water_point_view AS
 SELECT wp.osm_id,
        ST_PointOnSurface(wp.geometry) AS geometry,
        wp.name,
        wp.name_en,
        wp.name_de,
+       CASE
+           WHEN "natural" = 'bay' THEN 'bay'
+           WHEN place = 'sea' THEN 'sea'
+           ELSE 'lake'
+       END AS class,
        update_tags(wp.tags, ST_PointOnSurface(wp.geometry)) AS tags,
-       ST_Area(wp.geometry) AS area,
+       -- Area of the feature in square meters
+       ST_Area(wp.geometry) as area,
        wp.is_intermittent
 FROM osm_water_polygon AS wp
          LEFT JOIN lake_centerline ll ON wp.osm_id = ll.osm_id
@@ -17,11 +25,25 @@ WHERE ll.osm_id IS NULL
   AND wp.name <> ''
   AND ST_IsValid(wp.geometry);
 
--- etldoc:  osm_water_polygon ->  osm_water_point
+-- etldoc:  osm_water_point_view ->  osm_water_point_earth_view
--- etldoc:  lake_centerline ->  osm_water_point
+CREATE OR REPLACE VIEW osm_water_point_earth_view AS
+SELECT osm_id,
+       geometry,
+       name,
+       name_en,
+       name_de,
+       class,
+       tags,
+       -- Percentage of the earth's surface covered by this feature (approximately)
+       -- The constant below is 111,842^2 * 180 * 180, where 111,842 is the length of one degree of latitude at the equator in meters.
+       area / (405279708033600 * COS(ST_Y(ST_Transform(geometry,4326))*PI()/180)) as earth_area,
+       is_intermittent
+FROM osm_water_point_view;
+
+-- etldoc:  osm_water_point_earth_view ->  osm_water_point
 CREATE TABLE IF NOT EXISTS osm_water_point AS
 SELECT *
-FROM osm_water_point_view;
+FROM osm_water_point_earth_view;
 DO
 $$
     BEGIN

layers/water_name/water_name.sql

@@ -46,12 +46,14 @@ SELECT
     COALESCE(NULLIF(name_en, ''), name) AS name_en,
     COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
     tags,
-    'lake'::text AS class,
+    class,
     is_intermittent::int AS intermittent
 FROM osm_water_point
 WHERE geometry && bbox
   AND (
-        (zoom_level BETWEEN 9 AND 13 AND area > 70000 * 2 ^ (20 - zoom_level))
+        -- Show a label if a water feature covers at least 1/4 of a tile or z14+
+        (tags->'place' IN ('sea', 'ocean') AND POWER(4,zoom_level) * earth_area > 0.25)
+        OR (zoom_level BETWEEN 3 AND 13 AND POWER(4,zoom_level) * earth_area > 0.25)
         OR (zoom_level >= 14)
     )
 UNION ALL
@@ -65,15 +67,15 @@ SELECT
     COALESCE(NULLIF(name_en, ''), name) AS name_en,
     COALESCE(NULLIF(name_de, ''), name, name_en) AS name_de,
     tags,
-    place::text AS class,
+    COALESCE(NULLIF("natural",''), "place") AS class,
     is_intermittent::int AS intermittent
 FROM osm_marine_point
 WHERE geometry && bbox
-  AND (
+  AND CASE
-        place = 'ocean'
+      WHEN place = 'ocean' THEN TRUE
-        OR (zoom_level >= "rank" AND "rank" IS NOT NULL)
+      WHEN zoom_level >= "rank" AND "rank" IS NOT NULL THEN TRUE
-        OR (zoom_level >= 8)
+      WHEN "natural" = 'bay' THEN zoom_level >= 13
-    );
+      ELSE zoom_level >= 8 END;
 $$ LANGUAGE SQL STABLE
                 -- STRICT
                 PARALLEL SAFE;

layers/water_name/water_name.yaml

@@ -14,9 +14,11 @@ layer:
     name_de: German name `name:de` if available, otherwise `name` or `name:en`.
     class:
       description: |
-          Distinguish between `lake`, `ocean` and `sea`.
+          Distinguish between `lake`, `ocean`, `bay`, `strait`, and `sea`.
       values:
       - lake
+      - bay
+      - strait
       - sea
       - ocean
     intermittent: