Use buildings from imposm3 mapping.

layers/building/building.sql

@@ -1,22 +1,22 @@
 CREATE OR REPLACE VIEW building_z13 AS (
-    SELECT osm_id, way, height, levels FROM buildings WHERE way_area > 1400
+    SELECT osm_id, geometry, height, levels FROM osm_building_polygon_gen1 WHERE area > 1400
 );
 
 CREATE OR REPLACE VIEW building_z14 AS (
-    SELECT osm_id, way, height, levels FROM buildings
+    SELECT osm_id, geometry, height, levels FROM osm_building_polygon
 );
 
 CREATE OR REPLACE FUNCTION layer_building(bbox geometry, zoom_level int)
-RETURNS TABLE(geom geometry, osm_id bigint, render_height float) AS $$
-    SELECT way, osm_id,
+RETURNS TABLE(geom geometry, osm_id bigint, render_height numeric) AS $$
+    SELECT geometry, osm_id,
     least(greatest(3, COALESCE(height, levels*3.66,5)),400)^.7 AS render_height
     FROM (
-        SELECT osm_id, ST_Simplify(way, 10) AS way, height, levels FROM building_z13
-        WHERE zoom_level = 13 AND way && bbox
+        SELECT osm_id, ST_Simplify(geometry, 10) AS geometry, height, levels FROM building_z13
+        WHERE zoom_level = 13 AND geometry && bbox
         UNION ALL
         SELECT * FROM building_z14
-        WHERE zoom_level >= 14 AND way && bbox
+        WHERE zoom_level >= 14 AND geometry && bbox
     ) AS zoom_levels
-    ORDER BY render_height, ST_YMin(way) DESC;
+    ORDER BY render_height, ST_YMin(geometry) DESC;
 $$ LANGUAGE SQL IMMUTABLE;
 

layers/building/building.yaml

@@ -1,12 +1,15 @@
 layer:
   id: "building"
-  description: Roads
+  description: |
+    All [OSM Buildings](http://wiki.openstreetmap.org/wiki/Buildings).
   buffer_size: 4
   datasource:
     query: (SELECT * FROM layer_building(!bbox!, z(!scale_denominator!))) AS t
   fields:
-    admin_level: Number
-    class: String
-    scalerank: Number
+    render_height: |
+        An approximated height from levels and height of building after the method of Paul Norman in [OSM Clear](https://github.com/ClearTables/osm-clear)
 schema:
   - ./building.sql
+datasources:
+  - type: imposm3
+    mapping_file: ./mapping.yaml

layers/building/mapping.yaml

@@ -0,0 +1,24 @@
+generalized_tables:
+  building_polygon_gen1:
+    source: building_polygon
+    sql_filter: area>1400.0
+    tolerance: 10.0
+tables:
+  building_polygon:
+    fields:
+    - name: osm_id
+      type: id
+    - name: geometry
+      type: validated_geometry
+    - name: area
+      type: pseudoarea
+    - name: height
+      key: height
+      type: integer
+    - name: levels
+      key: levels
+      type: integer
+    mapping:
+      building:
+      - __any__
+    type: polygon