min source feature size for centroid/point on surface/centroid if convex

planetiler-core/src/main/java/com/onthegomap/planetiler/FeatureCollector.java

@@ -230,6 +230,10 @@ private Feature(String layer, Geometry geom, long id) {
       this.geom = geom;
       this.geometryType = GeometryType.typeOf(geom);
       this.id = id;
+      if (geometryType == GeometryType.POINT) {
+        minPixelSizeAtMaxZoom = 0;
+        defaultMinPixelSize = 0;
+      }
     }
 
     /** Returns the original ID of the source feature that this feature came from (i.e. OSM node/way ID). */
@@ -728,5 +732,15 @@ public String toString() {
         ", attrs=" + attrs +
         '}';
     }
+
+    /** Returns the actual pixel size of the source feature at {@code zoom} (length if line, sqrt(area) if polygon). */
+    public double getSourceFeaturePixelSizeAtZoom(int zoom) {
+      try {
+        return source.size() * (256 << zoom);
+      } catch (GeometryException e) {
+        e.log(stats, "point_get_size_failure", "Error getting min size for point from geometry " + source.id());
+        return 0;
+      }
+    }
   }
 }

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

@@ -39,6 +39,7 @@ public abstract class SourceFeature implements WithTags, WithGeometryType {
   private Geometry validPolygon = null;
   private double area = Double.NaN;
   private double length = Double.NaN;
+  private double size = Double.NaN;
 
   /**
    * Constructs a new input feature.
@@ -245,6 +246,14 @@ public double length() throws GeometryException {
       (isPoint() || canBePolygon() || canBeLine()) ? worldGeometry().getLength() : 0) : length;
   }
 
+  /**
+   * Returns and caches sqrt of {@link #area()} if polygon or {@link #length()} if a line string.
+   */
+  public double size() throws GeometryException {
+    return Double.isNaN(size) ? (size = canBePolygon() ? Math.sqrt(Math.abs(area())) : canBeLine() ? length() : 0) :
+      size;
+  }
+
   /** Returns the ID of the source that this feature came from. */
   public String getSource() {
     return source;
@@ -292,4 +301,5 @@ public final long id() {
   public boolean hasRelationInfo() {
     return relationInfos != null && !relationInfos.isEmpty();
   }
+
 }

planetiler-core/src/main/java/com/onthegomap/planetiler/render/FeatureRenderer.java

@@ -97,6 +97,10 @@ private void renderPoint(FeatureCollector.Feature feature, Coordinate... origCoo
       coords[i] = origCoords[i].copy();
     }
     for (int zoom = feature.getMaxZoom(); zoom >= feature.getMinZoom(); zoom--) {
+      double minSize = feature.getMinPixelSizeAtZoom(zoom);
+      if (minSize > 0 && feature.getSourceFeaturePixelSizeAtZoom(zoom) < minSize) {
+        continue;
+      }
       Map<String, Object> attrs = feature.getAttrsAtZoom(zoom);
       double buffer = feature.getBufferPixelsAtZoom(zoom) / 256;
       int tilesAtZoom = 1 << zoom;
@@ -207,7 +211,7 @@ private void renderLineOrPolygon(FeatureCollector.Feature feature, Geometry inpu
       }
       Map<String, Object> attrs = feature.getAttrsAtZoom(sliced.zoomLevel());
       if (numPointsAttr != null) {
-        // if profile wants the original number of points that the simplified but untiled geometry started with
+        // if profile wants the original number off points that the simplified but untiled geometry started with
         attrs = new HashMap<>(attrs);
         attrs.put(numPointsAttr, geom.getNumPoints());
       }

planetiler-core/src/test/java/com/onthegomap/planetiler/FeatureCollectorTest.java

@@ -614,5 +614,4 @@ void testManyAttr() {
       )
     ), collector);
   }
-
 }

planetiler-core/src/test/java/com/onthegomap/planetiler/PlanetilerTests.java

@@ -592,6 +592,15 @@ public List<Coordinate> z14CoordinateList(double... coords) {
     return points;
   }
 
+  public List<Coordinate> z14PixelRectangle(double min, double max) {
+    List<Coordinate> points = rectangleCoordList(min / 256d, max / 256d);
+    points.forEach(c -> {
+      c.x = GeoUtils.getWorldLon(0.5 + c.x * Z14_WIDTH);
+      c.y = GeoUtils.getWorldLat(0.5 + c.y * Z14_WIDTH);
+    });
+    return points;
+  }
+
   public List<Coordinate> z14CoordinatePixelList(double... coords) {
     return z14CoordinateList(DoubleStream.of(coords).map(c -> c / 256d).toArray());
   }
@@ -2341,6 +2350,90 @@ void testBoundFilters() throws Exception {
     assertEquals(bboxResult.tiles, polyResult.tiles);
   }
 
+  @Test
+  void testSimplePolygon() throws Exception {
+    List<Coordinate> points = z14PixelRectangle(0, 40);
+
+    var results = runWithReaderFeatures(
+      Map.of("threads", "1"),
+      List.of(
+        newReaderFeature(newPolygon(points), Map.of())
+      ),
+      (in, features) -> features.polygon("layer")
+        .setZoomRange(0, 14)
+        .setBufferPixels(0)
+        .setMinPixelSize(10) // should only show up z14 (40) z13 (20) and z12 (10)
+    );
+
+    assertEquals(Map.ofEntries(
+      newTileEntry(Z12_TILES / 2, Z12_TILES / 2, 12, List.of(
+        feature(newPolygon(rectangleCoordList(0, 10)), Map.of())
+      )),
+      newTileEntry(Z13_TILES / 2, Z13_TILES / 2, 13, List.of(
+        feature(newPolygon(rectangleCoordList(0, 20)), Map.of())
+      )),
+      newTileEntry(Z14_TILES / 2, Z14_TILES / 2, 14, List.of(
+        feature(newPolygon(rectangleCoordList(0, 40)), Map.of())
+      ))
+    ), results.tiles);
+  }
+
+  @Test
+  void testCentroidWithPolygonMinSize() throws Exception {
+    List<Coordinate> points = z14PixelRectangle(0, 40);
+
+    var results = runWithReaderFeatures(
+      Map.of("threads", "1"),
+      List.of(
+        newReaderFeature(newPolygon(points), Map.of())
+      ),
+      (in, features) -> features.centroid("layer")
+        .setZoomRange(0, 14)
+        .setBufferPixels(0)
+        .setMinPixelSize(10) // should only show up z14 (40) z13 (20) and z12 (10)
+    );
+
+    assertEquals(Map.ofEntries(
+      newTileEntry(Z12_TILES / 2, Z12_TILES / 2, 12, List.of(
+        feature(newPoint(5, 5), Map.of())
+      )),
+      newTileEntry(Z13_TILES / 2, Z13_TILES / 2, 13, List.of(
+        feature(newPoint(10, 10), Map.of())
+      )),
+      newTileEntry(Z14_TILES / 2, Z14_TILES / 2, 14, List.of(
+        feature(newPoint(20, 20), Map.of())
+      ))
+    ), results.tiles);
+  }
+
+  @Test
+  void testCentroidWithLineMinSize() throws Exception {
+    List<Coordinate> points = z14CoordinatePixelList(0, 4, 40, 4);
+
+    var results = runWithReaderFeatures(
+      Map.of("threads", "1"),
+      List.of(
+        newReaderFeature(newLineString(points), Map.of())
+      ),
+      (in, features) -> features.centroid("layer")
+        .setZoomRange(0, 14)
+        .setBufferPixels(0)
+        .setMinPixelSize(10) // should only show up z14 (40) z13 (20) and z12 (10)
+    );
+
+    assertEquals(Map.ofEntries(
+      newTileEntry(Z12_TILES / 2, Z12_TILES / 2, 12, List.of(
+        feature(newPoint(5, 1), Map.of())
+      )),
+      newTileEntry(Z13_TILES / 2, Z13_TILES / 2, 13, List.of(
+        feature(newPoint(10, 2), Map.of())
+      )),
+      newTileEntry(Z14_TILES / 2, Z14_TILES / 2, 14, List.of(
+        feature(newPoint(20, 4), Map.of())
+      ))
+    ), results.tiles);
+  }
+
   @Test
   void testBoundFiltersFill() throws Exception {
     var polyResultz8 = runForBoundsTest(8, 8, "polygon", TestUtils.pathToResource("bottomrightearth.poly").toString());