From 6d9708e7e8688727fbb6e1db04cf667854addba7 Mon Sep 17 00:00:00 2001 From: Anton Tananaev Date: Thu, 19 Nov 2020 22:09:54 -0800 Subject: Fix polygon area calculation --- .../java/org/traccar/geofence/GeofencePolygon.java | 40 +++++++--------------- 1 file changed, 12 insertions(+), 28 deletions(-) (limited to 'src/main/java/org/traccar') diff --git a/src/main/java/org/traccar/geofence/GeofencePolygon.java b/src/main/java/org/traccar/geofence/GeofencePolygon.java index c03a71225..cd2cbf16a 100644 --- a/src/main/java/org/traccar/geofence/GeofencePolygon.java +++ b/src/main/java/org/traccar/geofence/GeofencePolygon.java @@ -15,9 +15,16 @@ */ package org.traccar.geofence; +import org.locationtech.spatial4j.context.SpatialContext; +import org.locationtech.spatial4j.context.jts.JtsSpatialContextFactory; +import org.locationtech.spatial4j.shape.ShapeFactory; +import org.locationtech.spatial4j.shape.jts.JtsShapeFactory; + import java.text.ParseException; import java.util.ArrayList; +import static org.locationtech.spatial4j.distance.DistanceUtils.DEG_TO_KM; + public class GeofencePolygon extends GeofenceGeometry { public GeofencePolygon() { @@ -107,37 +114,14 @@ public class GeofencePolygon extends GeofenceGeometry { return oddNodes; } - private double toRadians(double input) { - return input / 180.0 * Math.PI; - } - - private double polarTriangleArea(double tan1, double lng1, double tan2, double lng2) { - double deltaLng = lng1 - lng2; - double t = tan1 * tan2; - return 2 * Math.atan2(t * Math.sin(deltaLng), 1 + t * Math.sin(deltaLng)); - } - @Override public double calculateArea() { - if (coordinates.size() < 3) { - return 0; - } - - double total = 0; - Coordinate prev = coordinates.get(coordinates.size() - 1); - double prevTanLat = Math.tan((Math.PI / 2 - toRadians(prev.getLat())) / 2); - double prevLng = toRadians(prev.getLon()); - - for (Coordinate point : coordinates) { - double tanLat = Math.tan((Math.PI / 2 - toRadians(point.getLat())) / 2); - double lng = toRadians(point.getLon()); - total += polarTriangleArea(tanLat, lng, prevTanLat, prevLng); - prevTanLat = tanLat; - prevLng = lng; + JtsShapeFactory jtsShapeFactory = new JtsSpatialContextFactory().newSpatialContext().getShapeFactory(); + ShapeFactory.PolygonBuilder polygonBuilder = jtsShapeFactory.polygon(); + for (Coordinate coordinate : coordinates) { + polygonBuilder.pointXY(coordinate.getLon(), coordinate.getLat()); } - - double earthRadius = 6371009; - return total * (earthRadius * earthRadius); + return polygonBuilder.build().getArea(SpatialContext.GEO) * DEG_TO_KM * DEG_TO_KM; } @Override -- cgit v1.2.3