Fix pedestrian area multipolygons (#63)

planetiler-basemap/src/main/java/com/onthegomap/planetiler/basemap/layers/Transportation.java

@@ -513,8 +513,9 @@ public class Transportation implements
   public void process(Tables.OsmHighwayPolygon element, FeatureCollector features) {
     String manMade = element.manMade();
     if (isBridgeOrPier(manMade) ||
-      // ignore underground pedestrian areas
-      (element.isArea() && element.layer() >= 0)) {
+      // only allow closed ways where area=yes, and multipolygons
+      // and ignore underground pedestrian areas
+      (!element.source().canBeLine() && element.layer() >= 0)) {
       String highwayClass = highwayClass(element.highway(), element.publicTransport(), null, element.manMade());
       if (highwayClass != null) {
         features.polygon(LAYER_NAME).setBufferPixels(BUFFER_SIZE)

planetiler-basemap/src/test/java/com/onthegomap/planetiler/basemap/layers/AbstractLayerTest.java

@@ -131,6 +131,17 @@ public abstract class AbstractLayerTest {
     );
   }
 
+  SourceFeature closedWayFeature(Map<String, Object> props) {
+    return SimpleFeature.createFakeOsmFeature(
+      newLineString(0, 0, 1, 0, 1, 1, 0, 1, 0, 0),
+      new HashMap<>(props),
+      OSM_SOURCE,
+      null,
+      0,
+      null
+    );
+  }
+
   SourceFeature polygonFeatureWithArea(double area, Map<String, Object> props) {
     return SimpleFeature.create(
       GeoUtils.worldToLatLonCoords(rectangle(0, Math.sqrt(area))),

planetiler-basemap/src/test/java/com/onthegomap/planetiler/basemap/layers/TransportationTest.java

@@ -990,7 +990,7 @@ public class TransportationTest extends AbstractLayerTest {
 
   @Test
   public void testPedestrianArea() {
-    assertFeatures(10, List.of(Map.of(
+    Map<String, Object> pedestrianArea = Map.of(
       "_layer", "transportation",
       "class", "path",
       "subclass", "pedestrian",
@@ -998,13 +998,36 @@ public class TransportationTest extends AbstractLayerTest {
       "_minzoom", 13,
       "_maxzoom", 14,
       "_type", "polygon"
-    )), process(polygonFeature(Map.of(
+    );
+    Map<String, Object> circularPath = Map.of(
+      "_layer", "transportation",
+      "class", "path",
+      "subclass", "pedestrian",
+
+      "_minzoom", 14,
+      "_maxzoom", 14,
+      "_type", "line"
+    );
+    assertFeatures(14, List.of(pedestrianArea), process(closedWayFeature(Map.of(
       "highway", "pedestrian",
       "area", "yes",
       "foot", "yes"
     ))));
+    assertFeatures(14, List.of(pedestrianArea), process(polygonFeature(Map.of(
+      "highway", "pedestrian",
+      "foot", "yes"
+    ))));
+    assertFeatures(14, List.of(circularPath), process(closedWayFeature(Map.of(
+      "highway", "pedestrian",
+      "foot", "yes"
+    ))));
+    assertFeatures(14, List.of(circularPath), process(closedWayFeature(Map.of(
+      "highway", "pedestrian",
+      "foot", "yes",
+      "area", "no"
+    ))));
     // ignore underground pedestrian areas
-    assertFeatures(10, List.of(),
+    assertFeatures(14, List.of(),
       process(polygonFeature(Map.of(
         "highway", "pedestrian",
         "area", "yes",

planetiler-core/src/main/java/com/onthegomap/planetiler/reader/SimpleFeature.java

@@ -8,7 +8,9 @@ import java.util.Map;
 import java.util.Objects;
 import java.util.concurrent.atomic.AtomicLong;
 import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.LineString;
 import org.locationtech.jts.geom.Lineal;
+import org.locationtech.jts.geom.MultiLineString;
 import org.locationtech.jts.geom.Polygonal;
 import org.locationtech.jts.geom.Puntal;
 
@@ -77,7 +79,26 @@ public class SimpleFeature extends SourceFeature {
   /** Returns a new feature with OSM relation info. Useful for setting up inputs for OSM unit tests. */
   public static SimpleFeature createFakeOsmFeature(Geometry latLonGeometry, Map<String, Object> tags, String source,
     String sourceLayer, long id, List<OsmReader.RelationMember<OsmRelationInfo>> relations) {
-    return new SimpleFeature(latLonGeometry, null, tags, source, sourceLayer, id, relations);
+    String area = (String) tags.get("area");
+    return new SimpleFeature(latLonGeometry, null, tags, source, sourceLayer, id, relations) {
+      @Override
+      public boolean canBePolygon() {
+        return latLonGeometry instanceof Polygonal || (latLonGeometry instanceof LineString line
+          && OsmReader.canBePolygon(line.isClosed(), area, latLonGeometry.getNumPoints()));
+      }
+
+      @Override
+      public boolean canBeLine() {
+        return latLonGeometry instanceof MultiLineString || (latLonGeometry instanceof LineString line
+          && OsmReader.canBeLine(line.isClosed(), area, latLonGeometry.getNumPoints()));
+      }
+
+      @Override
+      protected Geometry computePolygon() {
+        var geom = worldGeometry();
+        return geom instanceof LineString line ? GeoUtils.JTS_FACTORY.createPolygon(line.getCoordinates()) : geom;
+      }
+    };
   }
 
   @Override

planetiler-core/src/main/java/com/onthegomap/planetiler/reader/osm/OsmReader.java

@@ -514,6 +514,16 @@ public class OsmReader implements Closeable, MemoryEstimator.HasEstimate {
     }
   }
 
+  /** Returns {@code true} if a way can be interpreted as a line. */
+  public static boolean canBeLine(boolean closed, String area, int points) {
+    return (!closed || !"yes".equals(area)) && points >= 2;
+  }
+
+  /** Returns {@code true} if a way can be interpreted as a polygon. */
+  public static boolean canBePolygon(boolean closed, String area, int points) {
+    return (closed && !"no".equals(area)) && points >= 4;
+  }
+
   /**
    * A {@link LineString} or {@link Polygon} created from an OSM way.
    * <p>
@@ -529,8 +539,8 @@ public class OsmReader implements Closeable, MemoryEstimator.HasEstimate {
     public WaySourceFeature(ReaderWay way, boolean closed, String area, NodeLocationProvider nodeLocations,
       List<RelationMember<OsmRelationInfo>> relationInfo) {
       super(way, false,
-        (!closed || !"yes".equals(area)) && way.getNodes().size() >= 2, // line
-        (closed && !"no".equals(area)) && way.getNodes().size() >= 4, // polygon
+        OsmReader.canBeLine(closed, area, way.getNodes().size()),
+        OsmReader.canBePolygon(closed, area, way.getNodes().size()),
         relationInfo
       );
       this.nodeIds = way.getNodes();