fix non-noded intersection between shoreline clipped and non-shoreline clipped geometries by using a safe_intersection function

src/pg/sql/40_observatory_utility.sql

@@ -231,3 +231,22 @@ CREATE AGGREGATE cdb_observatory.FIRST (
         basetype = anyelement,
         stype    = anyelement
 );
+
+-- Attempt to perform intersection, if there's an exception then buffer
+-- https://gis.stackexchange.com/questions/50399/how-best-to-fix-a-non-noded-intersection-problem-in-postgis
+CREATE OR REPLACE FUNCTION cdb_observatory.safe_intersection(geom_a geometry, geom_b geometry)
+RETURNS geometry AS
+$$
+BEGIN
+    RETURN ST_Intersection(geom_a, geom_b);
+    EXCEPTION
+        WHEN OTHERS THEN
+            BEGIN
+                RETURN ST_Intersection(ST_Buffer(geom_a, 0.0000001), ST_Buffer(geom_b, 0.0000001));
+                EXCEPTION
+                    WHEN OTHERS THEN
+                        RETURN ST_GeomFromText('POLYGON EMPTY');
+    END;
+END
+$$
+LANGUAGE 'plpgsql' STABLE STRICT;