Reduce transportation_name segmentation (#1643)

This PR reduces transportation_name layer fragmentation by ensuring the short brunnel segments are merged rather than dropped from view.

---------

Co-authored-by: Tomas Pohanka <TomPohys@gmail.com>

layers/transportation/update_transportation_merge.sql

@@ -42,6 +42,23 @@ SELECT
 $$ LANGUAGE SQL IMMUTABLE
                 PARALLEL SAFE;
 
+-- Determine whether a segment is long enough to have an attribute
+CREATE OR REPLACE FUNCTION visible_text(g geometry, attr text, zoom_level integer)
+    RETURNS text AS
+$$
+SELECT
+    CASE WHEN
+    -- Width of a tile in meters (111,842 is the length of one degree of latitude at the equator in meters)
+    -- 111,842 * 180 / 2^zoom_level
+    --  = 20131560 / POW(2, zoom_level)
+    -- Drop brunnel if length of way < 2% of tile width (less than 3 pixels)
+    ST_Length(g) *
+        COS(RADIANS(ST_Y(ST_Centroid(ST_Transform(g, 4326))))) *
+        POW(2, zoom_level) / 20131560 > 0.02
+    THEN attr END
+$$ LANGUAGE SQL IMMUTABLE
+                PARALLEL SAFE;
+
 -- Instead of using relations to find out the road names we
 -- stitch together the touching ways with the same name
 -- to allow for nice label rendering

layers/transportation_name/transportation_name.sql

@@ -204,7 +204,7 @@ FROM (
                 indoor
          FROM osm_transportation_name_linestring
          WHERE zoom_level = 12
-           AND LineLabel(zoom_level, COALESCE(tags->'name', ref), geometry)
+           AND LineLabel(zoom_level, COALESCE(ref, tags->'name'), geometry)
            AND NOT highway_is_link(highway)
            AND
                CASE WHEN highway_class(highway, NULL::text, NULL::text) NOT IN ('path', 'minor') THEN TRUE
@@ -228,7 +228,7 @@ FROM (
                 indoor
          FROM osm_transportation_name_linestring
          WHERE zoom_level = 13
-           AND LineLabel(zoom_level, COALESCE(tags->'name', ref), geometry)
+           AND LineLabel(zoom_level, COALESCE(ref, tags->'name'), geometry)
            AND
                CASE WHEN highway <> 'path' THEN TRUE
                     WHEN highway = 'path' AND (

layers/transportation_name/update_transportation_name.sql

@@ -426,17 +426,17 @@ BEGIN
 
     -- etldoc: osm_transportation_name_linestring -> osm_transportation_name_linestring_gen1
     INSERT INTO osm_transportation_name_linestring_gen1 (id, geometry, tags, ref, highway, subclass, brunnel, network,
-                                                         route_1, route_2, route_3, route_4, route_5, route_6, z_order)
+                                                         route_1, route_2, route_3, route_4, route_5, route_6)
     SELECT MIN(id) as id,
            ST_Simplify(ST_LineMerge(ST_Collect(geometry)), 50) AS geometry,
            tags, ref, highway, subclass, brunnel, network,
-           route_1, route_2, route_3, route_4, route_5, route_6, z_order
+           route_1, route_2, route_3, route_4, route_5, route_6
     FROM (
         SELECT id,
                geometry,
                tags, ref, highway, subclass,
-               CASE WHEN ST_Length(geometry) > 8000 THEN brunnel ELSE '' END AS brunnel,
-               network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+               visible_text(geometry, brunnel, 9) AS brunnel,
+               network, route_1, route_2, route_3, route_4, route_5, route_6
         FROM osm_transportation_name_linestring
     ) osm_transportation_name_linestring_gen1_pre_merge
     WHERE (
@@ -449,12 +449,12 @@ BEGIN
     ) AND (
         (highway IN ('motorway', 'trunk') OR highway = 'construction' AND subclass IN ('motorway', 'trunk'))
     )
-    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6
     ON CONFLICT (id) DO UPDATE SET geometry = excluded.geometry, tags = excluded.tags, ref = excluded.ref,
                                      highway = excluded.highway, subclass = excluded.subclass,
                                      brunnel = excluded.brunnel, network = excluded.network, route_1 = excluded.route_1,
                                      route_2 = excluded.route_2, route_3 = excluded.route_3, route_4 = excluded.route_4,
-                                     route_5 = excluded.route_5, route_6 = excluded.route_6, z_order = excluded.z_order;
+                                     route_5 = excluded.route_5, route_6 = excluded.route_6;
 
     -- Analyze source table
     ANALYZE osm_transportation_name_linestring_gen1;
@@ -469,17 +469,17 @@ BEGIN
 
     -- etldoc: osm_transportation_name_linestring_gen1 -> osm_transportation_name_linestring_gen2
     INSERT INTO osm_transportation_name_linestring_gen2 (id, geometry, tags, ref, highway, subclass, brunnel, network,
-                                                         route_1, route_2, route_3, route_4, route_5, route_6, z_order)
+                                                         route_1, route_2, route_3, route_4, route_5, route_6)
     SELECT MIN(id) as id,
            ST_Simplify(ST_LineMerge(ST_Collect(geometry)), 120) AS geometry,
            tags, ref, highway, subclass, brunnel, network,
-           route_1, route_2, route_3, route_4, route_5, route_6, z_order
+           route_1, route_2, route_3, route_4, route_5, route_6
     FROM (
         SELECT id,
                (ST_Dump(geometry)).geom AS geometry,
                tags, ref, highway, subclass,
-               CASE WHEN ST_Length(geometry) > 14000 THEN brunnel ELSE '' END AS brunnel,
-               network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+               visible_text(geometry, brunnel, 8) AS brunnel,
+               network, route_1, route_2, route_3, route_4, route_5, route_6
         FROM osm_transportation_name_linestring_gen1
     ) osm_transportation_name_linestring_gen2_pre_merge
     WHERE (
@@ -492,12 +492,12 @@ BEGIN
     ) AND (
         (highway IN ('motorway', 'trunk') OR highway = 'construction' AND subclass IN ('motorway', 'trunk'))
     )
-    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6
     ON CONFLICT (id) DO UPDATE SET geometry = excluded.geometry, tags = excluded.tags, ref = excluded.ref,
                                      highway = excluded.highway, subclass = excluded.subclass,
                                      brunnel = excluded.brunnel, network = excluded.network, route_1 = excluded.route_1,
                                      route_2 = excluded.route_2, route_3 = excluded.route_3, route_4 = excluded.route_4,
-                                     route_5 = excluded.route_5, route_6 = excluded.route_6, z_order = excluded.z_order;
+                                     route_5 = excluded.route_5, route_6 = excluded.route_6;
 
     -- Analyze source table
     ANALYZE osm_transportation_name_linestring_gen2;
@@ -512,17 +512,17 @@ BEGIN
 
     -- etldoc: osm_transportation_name_linestring_gen2 -> osm_transportation_name_linestring_gen3
     INSERT INTO osm_transportation_name_linestring_gen3 (id, geometry, tags, ref, highway, subclass, brunnel, network,
-                                                         route_1, route_2, route_3, route_4, route_5, route_6, z_order)
+                                                         route_1, route_2, route_3, route_4, route_5, route_6)
     SELECT MIN(id) as id,
            ST_Simplify(ST_LineMerge(ST_Collect(geometry)), 200) AS geometry,
            tags, ref, highway, subclass, brunnel, network,
-           route_1, route_2, route_3, route_4, route_5, route_6, z_order
+           route_1, route_2, route_3, route_4, route_5, route_6
     FROM (
         SELECT id,
                (ST_Dump(geometry)).geom AS geometry,
                tags, ref, highway, subclass,
-               CASE WHEN ST_Length(geometry) > 20000 THEN brunnel ELSE '' END AS brunnel,
-               network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+               visible_text(geometry, brunnel, 7) AS brunnel,
+               network, route_1, route_2, route_3, route_4, route_5, route_6
         FROM osm_transportation_name_linestring_gen2
     ) osm_transportation_name_linestring_gen3_pre_merge
     WHERE (
@@ -535,12 +535,12 @@ BEGIN
     ) AND (
         (highway = 'motorway' OR highway = 'construction' AND subclass = 'motorway')
     )
-    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6, z_order
+    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6
     ON CONFLICT (id) DO UPDATE SET geometry = excluded.geometry, tags = excluded.tags, ref = excluded.ref,
                                      highway = excluded.highway, subclass = excluded.subclass,
                                      brunnel = excluded.brunnel, network = excluded.network, route_1 = excluded.route_1,
                                      route_2 = excluded.route_2, route_3 = excluded.route_3, route_4 = excluded.route_4,
-                                     route_5 = excluded.route_5, route_6 = excluded.route_6, z_order = excluded.z_order;
+                                     route_5 = excluded.route_5, route_6 = excluded.route_6;
 
     -- Analyze source table
     ANALYZE osm_transportation_name_linestring_gen3;
@@ -555,25 +555,36 @@ BEGIN
 
     -- etldoc: osm_transportation_name_linestring_gen3 -> osm_transportation_name_linestring_gen4
     INSERT INTO osm_transportation_name_linestring_gen4 (id, geometry, tags, ref, highway, subclass, brunnel, network,
-                                                         route_1, route_2, route_3, route_4, route_5, route_6, z_order)
-    SELECT id, ST_Simplify(geometry, 500) AS geometry, tags, ref, highway, subclass, brunnel, network, route_1, route_2,
-           route_3, route_4, route_5, route_6, z_order
+                                                         route_1, route_2, route_3, route_4, route_5, route_6)
+    SELECT MIN(id) as id,
+           ST_Simplify(ST_LineMerge(ST_Collect(geometry)), 500) AS geometry,
+           tags, ref, highway, subclass, brunnel, network,
+           route_1, route_2, route_3, route_4, route_5, route_6
+    FROM (
+        SELECT id,
+               (ST_Dump(geometry)).geom AS geometry,
+               tags, ref, highway, subclass,
+               visible_text(geometry, brunnel, 6) AS brunnel,
+               network, route_1, route_2, route_3, route_4, route_5, route_6
         FROM osm_transportation_name_linestring_gen3
+    ) osm_transportation_name_linestring_gen4_pre_merge
     WHERE (
         full_update IS TRUE OR EXISTS (
             SELECT NULL
             FROM transportation_name.name_changes_gen
             WHERE transportation_name.name_changes_gen.is_old IS FALSE AND
-                  transportation_name.name_changes_gen.id = osm_transportation_name_linestring_gen3.id
+                  transportation_name.name_changes_gen.id = osm_transportation_name_linestring_gen4_pre_merge.id
         )
     ) AND (
-        (highway = 'motorway' OR highway = 'construction' AND subclass = 'motorway') AND
-        ST_Length(geometry) > 20000
-    ) ON CONFLICT (id) DO UPDATE SET geometry = excluded.geometry, tags = excluded.tags, ref = excluded.ref,
+        ST_Length(geometry) > 20000 AND
+        (highway = 'motorway' OR highway = 'construction' AND subclass = 'motorway')
+    )
+    GROUP BY tags, ref, highway, subclass, brunnel, network, route_1, route_2, route_3, route_4, route_5, route_6
+    ON CONFLICT (id) DO UPDATE SET geometry = excluded.geometry, tags = excluded.tags, ref = excluded.ref,
                                      highway = excluded.highway, subclass = excluded.subclass,
                                      brunnel = excluded.brunnel, network = excluded.network, route_1 = excluded.route_1,
                                      route_2 = excluded.route_2, route_3 = excluded.route_3, route_4 = excluded.route_4,
-                                     route_5 = excluded.route_5, route_6 = excluded.route_6, z_order = excluded.z_order;
+                                     route_5 = excluded.route_5, route_6 = excluded.route_6;
 
     -- noinspection SqlWithoutWhere
     DELETE FROM transportation_name.name_changes_gen;