close open ways when end-nodes are close to each other but not identical

element/element.go

@@ -2,6 +2,7 @@ package element
 
 import (
 	"fmt"
+	"math"
 	"sort"
 
 	"github.com/omniscale/imposm3/geom/geos"
@@ -40,6 +41,26 @@ func (w *Way) IsClosed() bool {
 	return len(w.Refs) >= 4 && w.Refs[0] == w.Refs[len(w.Refs)-1]
 }
 
+func (w *Way) TryClose(maxGap float64) bool {
+	return TryCloseWay(w.Refs, w.Nodes, maxGap)
+}
+
+// TryCloseWay closes the way if both end nodes are nearly identical.
+// Returns true if it succeeds.
+func TryCloseWay(refs []int64, nodes []Node, maxGap float64) bool {
+	if len(refs) < 4 {
+		return false
+	}
+	start, end := nodes[0], nodes[len(nodes)-1]
+	dist := math.Hypot(start.Lat-end.Lat, start.Long-end.Long)
+	if dist < maxGap {
+		refs[len(refs)-1] = refs[0]
+		nodes[len(nodes)-1] = nodes[0]
+		return true
+	}
+	return false
+}
+
 type MemberType int
 
 const (

geom/ring.go

@@ -1,8 +1,6 @@
 package geom
 
 import (
-	"math"
-
 	"github.com/omniscale/imposm3/element"
 	"github.com/omniscale/imposm3/geom/geos"
 )
@@ -22,20 +20,8 @@ func (r *Ring) IsClosed() bool {
 	return len(r.refs) >= 4 && r.refs[0] == r.refs[len(r.refs)-1]
 }
 
-// TryClose closes the ring if both end nodes are nearly identical.
-// Returns true if it succeeds.
 func (r *Ring) TryClose(maxRingGap float64) bool {
-	if len(r.refs) < 4 {
+	return element.TryCloseWay(r.refs, r.nodes, maxRingGap)
-		return false
-	}
-	start, end := r.nodes[0], r.nodes[len(r.nodes)-1]
-	dist := math.Hypot(start.Lat-end.Lat, start.Long-end.Long)
-	if dist < maxRingGap {
-		r.refs[len(r.refs)-1] = r.refs[0]
-		r.nodes[len(r.nodes)-1] = r.nodes[0]
-		return true
-	}
-	return false
 }
 
 func (r *Ring) MarkInserted(tags element.Tags) {

test/complete_db.osm

@@ -353,7 +353,7 @@
     <tag k="name" v="self-intersecting"/>
   </way>
 
-  <!-- relation with "gap" (ways overlap, but are only sharing one endpoint) -->
+  <!-- relation/way with "gap" (ways overlap, but are only sharing one endpoint) -->
   <node id="7301" version="1" timestamp="2011-11-11T00:11:11Z" lat="60" lon="60"/>
   <node id="7302" version="1" timestamp="2011-11-11T00:11:11Z" lat="60" lon="62"/>
   <node id="7303" version="1" timestamp="2011-11-11T00:11:11Z" lat="62" lon="62"/>
@@ -377,6 +377,15 @@
     <tag k="type" v="multipolygon"/>
   </relation>
 
+  <way id="7311" version="1" timestamp="2011-11-11T00:11:11Z">
+    <nd ref="7313"/> <!-- same coord as 7303 -->
+    <nd ref="7314"/>
+    <nd ref="7301"/>
+    <nd ref="7302"/>
+    <nd ref="7303"/>
+    <tag k="landuse" v="park"/>
+  </way>
+
   <!-- test that single node ways or incomplete polygons are _not_ inserted -->
   <node id="30001" version="1" timestamp="2011-11-11T00:11:11Z" lat="47" lon="80"/>
   <node id="30002" version="1" timestamp="2011-11-11T00:11:11Z" lat="47" lon="80"/>

test/complete_db_test.py

@@ -254,11 +254,14 @@ def test_generalized_linestring_is_valid():
     assert road['geometry'].is_valid, road['geometry'].wkt
     assert road['geometry'].length > 1000000
 
-def test_relation_with_gap():
+def test_ring_with_gap():
-    """Multipolygon with gap (overlapping but different endpoints) gets closed"""
+    """Multipolygon and way with gap (overlapping but different endpoints) gets closed"""
     park = t.query_row(t.db_conf, 'osm_landusages', -7301)
     assert park['geometry'].is_valid, park
 
+    park = t.query_row(t.db_conf, 'osm_landusages', 7311)
+    assert park['geometry'].is_valid, park
+
 def test_updated_nodes1():
     """Zig-Zag line is inserted."""
     road =  t.query_row(t.db_conf, 'osm_roads', 60000)

writer/relations.go

@@ -19,7 +19,7 @@ type RelationWriter struct {
 	singleIdSpace  bool
 	rel            chan *element.Relation
 	polygonMatcher mapping.RelWayMatcher
-	maxRingGap     float64
+	maxGap         float64
 }
 
 func NewRelationWriter(
@@ -32,9 +32,9 @@ func NewRelationWriter(
 	matcher mapping.RelWayMatcher,
 	srid int,
 ) *OsmElemWriter {
-	maxRingGap := 1e-1 // 0.1m
+	maxGap := 1e-1 // 0.1m
 	if srid == 4326 {
-		maxRingGap = 1e-6 // ~0.1m
+		maxGap = 1e-6 // ~0.1m
 	}
 	rw := RelationWriter{
 		OsmElemWriter: OsmElemWriter{
@@ -48,7 +48,7 @@ func NewRelationWriter(
 		singleIdSpace:  singleIdSpace,
 		polygonMatcher: matcher,
 		rel:            rel,
-		maxRingGap:     maxRingGap,
+		maxGap:         maxGap,
 	}
 	rw.OsmElemWriter.writer = &rw
 	return &rw.OsmElemWriter
@@ -96,7 +96,7 @@ NextRel:
 
 		// prepare relation first (build rings and compute actual
 		// relation tags)
-		prepedRel, err := geom.PrepareRelation(r, rw.srid, rw.maxRingGap)
+		prepedRel, err := geom.PrepareRelation(r, rw.srid, rw.maxGap)
 		if err != nil {
 			if errl, ok := err.(ErrorLevel); !ok || errl.Level() > 0 {
 				log.Warn(err)

writer/ways.go

@@ -19,6 +19,7 @@ type WayWriter struct {
 	ways           chan *element.Way
 	lineMatcher    mapping.WayMatcher
 	polygonMatcher mapping.WayMatcher
+	maxGap         float64
 }
 
 func NewWayWriter(
@@ -32,6 +33,10 @@ func NewWayWriter(
 	lineMatcher mapping.WayMatcher,
 	srid int,
 ) *OsmElemWriter {
+	maxGap := 1e-1 // 0.1m
+	if srid == 4326 {
+		maxGap = 1e-6 // ~0.1m
+	}
 	ww := WayWriter{
 		OsmElemWriter: OsmElemWriter{
 			osmCache:  osmCache,
@@ -45,6 +50,7 @@ func NewWayWriter(
 		lineMatcher:    lineMatcher,
 		polygonMatcher: polygonMatcher,
 		ways:           ways,
+		maxGap:         maxGap,
 	}
 	ww.OsmElemWriter.writer = &ww
 	return &ww.OsmElemWriter
@@ -91,7 +97,7 @@ func (ww *WayWriter) loop() {
 			}
 			inserted = true
 		}
-		if w.IsClosed() && !insertedAsRelation {
+		if !insertedAsRelation && (w.IsClosed() || w.TryClose(ww.maxGap)) {
 			// only add polygons that were not inserted as a MultiPolygon relation
 			if matches := ww.polygonMatcher.MatchWay(w); len(matches) > 0 {
 				err := ww.buildAndInsert(geos, w, matches, true)