Changeset 9951 in josm
 Timestamp:
 20160307T23:29:23+01:00 (3 years ago)
 Location:
 trunk
 Files:

 2 edited
Legend:
 Unmodified
 Added
 Removed

trunk/src/org/openstreetmap/josm/tools/Geometry.java
r9231 r9951 31 31 import org.openstreetmap.josm.data.osm.RelationMember; 32 32 import org.openstreetmap.josm.data.osm.Way; 33 import org.openstreetmap.josm.data.projection.Projection; 34 import org.openstreetmap.josm.data.projection.Projections; 33 35 34 36 /** … … 630 632 /** 631 633 * Returns area of a closed way in square meters. 632 * (approximate(?), but should be OK for small areas)633 *634 * Relies on the current projection: Works correctly, when635 * one unit in projected coordinates corresponds to one meter.636 * This is true for most projections, but not for WGS84 and637 * Mercator (EPSG:3857).638 634 * 639 635 * @param way Way to measure, should be closed (first node is the same as last node) … … 641 637 */ 642 638 public static double closedWayArea(Way way) { 643 644 //http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/ 645 double area = 0; 646 Node lastN = null; 647 for (Node n : way.getNodes()) { 648 if (lastN != null) { 649 area += (calcX(n) * calcY(lastN))  (calcY(n) * calcX(lastN)); 650 } 651 lastN = n; 652 } 653 return Math.abs(area/2); 654 } 655 656 protected static double calcX(Node p1) { 657 double lat1, lon1, lat2, lon2; 658 double dlon, dlat; 659 660 lat1 = p1.getCoor().lat() * Math.PI / 180.0; 661 lon1 = p1.getCoor().lon() * Math.PI / 180.0; 662 lat2 = lat1; 663 lon2 = 0; 664 665 dlon = lon2  lon1; 666 dlat = lat2  lat1; 667 668 double a = Math.pow(Math.sin(dlat/2), 2) + Math.cos(lat1) * Math.cos(lat2) * Math.pow(Math.sin(dlon/2), 2); 669 double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1a)); 670 return 6367000 * c; 671 } 672 673 protected static double calcY(Node p1) { 674 double lat1, lon1, lat2, lon2; 675 double dlon, dlat; 676 677 lat1 = p1.getCoor().lat() * Math.PI / 180.0; 678 lon1 = p1.getCoor().lon() * Math.PI / 180.0; 679 lat2 = 0; 680 lon2 = lon1; 681 682 dlon = lon2  lon1; 683 dlat = lat2  lat1; 684 685 double a = Math.pow(Math.sin(dlat/2), 2) + Math.cos(lat1) * Math.cos(lat2) * Math.pow(Math.sin(dlon/2), 2); 686 double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1a)); 687 return 6367000 * c; 639 return getAreaAndPerimeter(way.getNodes(), Projections.getProjectionByCode("EPSG:54008")).getArea(); 688 640 } 689 641 … … 986 938 */ 987 939 public static AreaAndPerimeter getAreaAndPerimeter(List<Node> nodes) { 940 return getAreaAndPerimeter(nodes, null); 941 } 942 943 /** 944 * Calculate area and perimeter length of a polygon in the given projection. 945 * 946 * @param nodes the list of nodes representing the polygon 947 * @param projection the projection to use for the calculation, {@code null} defaults to {@link Main#getProjection()} 948 * @return area and perimeter 949 */ 950 public static AreaAndPerimeter getAreaAndPerimeter(List<Node> nodes, Projection projection) { 951 CheckParameterUtil.ensureParameterNotNull(nodes, "nodes"); 988 952 double area = 0; 989 953 double perimeter = 0; … … 991 955 boolean closed = nodes.get(0) == nodes.get(nodes.size()  1); 992 956 int numSegments = closed ? nodes.size()  1 : nodes.size(); 993 EastNorth p1 = nodes.get(0).getEastNorth();957 EastNorth p1 = projection == null ? nodes.get(0).getEastNorth() : projection.latlon2eastNorth(nodes.get(0).getCoor()); 994 958 for (int i = 1; i <= numSegments; i++) { 995 EastNorth p2 = nodes.get(i == numSegments ? 0 : i).getEastNorth(); 959 final Node node = nodes.get(i == numSegments ? 0 : i); 960 final EastNorth p2 = projection == null ? node.getEastNorth() : projection.latlon2eastNorth(node.getCoor()); 996 961 area += p1.east() * p2.north()  p2.east() * p1.north(); 997 962 perimeter += p1.distance(p2); 
trunk/test/unit/org/openstreetmap/josm/tools/GeometryTest.java
r9878 r9951 71 71 DataSet ds = OsmReader.parseDataSet(in, null); 72 72 Way closedWay = (Way) Utils.filter(ds.allPrimitives(), SearchCompiler.compile("landuse=forest")).iterator().next(); 73 Assert.assertEquals(57 21923.660644531, Geometry.closedWayArea(closedWay), 1e3);73 Assert.assertEquals(5760015.7353515625, Geometry.closedWayArea(closedWay), 1e3); 74 74 } 75 75 }
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