Merge branch 'master' of https://github.com/openmaptiles/openmaptiles into merge-github

# Conflicts:
#	Makefile
#	QUICKSTART.md
#	docker-compose.yml
#	layers/boundary/mapping.yaml
#	layers/landuse/landuse.sql
#	layers/landuse/landuse.yaml
#	layers/landuse/mapping.yaml
#	layers/poi/mapping.yaml
#	layers/poi/poi.sql
#	layers/poi/poi.yaml

layers/poi/poi.sql

@@ -94,20 +94,20 @@ FROM (
 
          -- etldoc: osm_poi_polygon ->  layer_poi:z12
          -- etldoc: osm_poi_polygon ->  layer_poi:z13
-         SELECT *,
-                NULL::integer AS agg_stop,
-                CASE
-                    WHEN osm_id < 0 THEN -osm_id * 10 + 4
-                    ELSE osm_id * 10 + 1
-                    END AS osm_id_hash
-         FROM osm_poi_polygon
-         WHERE geometry && bbox
-           AND zoom_level BETWEEN 12 AND 13
-           AND ((subclass = 'station' AND mapping_key = 'railway')
-             OR subclass IN ('halt', 'ferry_terminal'))
-
-         UNION ALL
-
+--          OLD
+--          SELECT *,
+--                 NULL::integer AS agg_stop,
+--                 CASE
+--                     WHEN osm_id < 0 THEN -osm_id * 10 + 4
+--                     ELSE osm_id * 10 + 1
+--                     END AS osm_id_hash
+--          FROM osm_poi_polygon
+--          WHERE geometry && bbox
+--            AND zoom_level BETWEEN 12 AND 13
+--            AND ((subclass = 'station' AND mapping_key = 'railway')
+--              OR subclass IN ('halt', 'ferry_terminal'))
+--
+--          UNION ALL
          -- etldoc: osm_poi_polygon ->  layer_poi:z14_
          SELECT *,
                 NULL::integer AS agg_stop,
@@ -116,8 +116,21 @@ FROM (
                     ELSE osm_id * 10 + 1
                     END AS osm_id_hash
          FROM osm_poi_polygon
-         WHERE geometry && bbox
-           AND zoom_level >= 14
+         WHERE geometry && bbox AND
+           CASE
+               WHEN zoom_level >= 14 THEN TRUE
+               WHEN zoom_level >= 12 AND
+                 ((subclass = 'station' AND mapping_key = 'railway')
+                 OR subclass IN ('halt', 'ferry_terminal')) THEN TRUE
+               WHEN zoom_level BETWEEN 10 AND 14 THEN
+                 subclass IN ('university', 'college') AND
+                 POWER(4,zoom_level)
+                 -- Compute 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))
+                 -- Match features that are at least 10% of a tile at this zoom
+                 > 0.10
+               ELSE FALSE END
      ) AS poi_union_raw
     WHERE NOT (mapping_key = 'building' AND (subclass = 'office' OR subclass = 'industrial') AND coalesce(name, name_en, '') = '')
 ) AS poi_union