Vjylku

I'm working on a Java project using Geo Tool API that want to get the interior point getInteriorPoint(), from the geometry coming from an intersection between a Polygon and a MultiLineString. Please note that the same approach works perfectly between a Polygon and MultiPolygon, so between objects with the same number of dimensions, I guess.

Let me explain better with a snippet of code (java Geo Tool API version 15.1):

if(feature.getDefaultGeometry() instanceof MultiLineString){



   MultiLineString multiLineString = ((MultiLineString) feature.getDefaultGeometry());



   //Interior point on intersection

   Coordinate intersectionInteriorPoint = this.getInteriorPointForIntersectedArea(polygon, multiLineString, sourceCRS);



}

where the getInteriorPointForIntersectedArea(..) is as this:

   /**

     * Compute the interior point for the overlapping area 

     * between the search geometry and an intersected geometry

     * @param one

     * @param two

     * @return the coordinate in the target output reference CRS

     */

    private Coordinate getInteriorPointForIntersectedArea(Polygon one, 

                                                          MultiLineString two, 

                                                          CoordinateReferenceSystem sourceCRS, 

                                                          Coordinate waypointCoordinate){



        com.vividsolutions.jts.geom.Geometry lineString = (com.vividsolutions.jts.geom.Geometry) one.intersection(two);



        System.out.println("Geometry type: " + lineString.getGeometryType());



        Coordinate interiorPointCoordinate = lineString.getInteriorPoint().getCoordinate();



        Coordinate interiorPointCoordinateChanged = null;

        try {

            interiorPointCoordinateChanged = CoordinateReferenceSystemTools.FromToCRS(sourceCRS, 

                                                                                      org.geotools.referencing.crs.DefaultGeographicCRS.WGS84, 

                                                                                      interiorPointCoordinate, 

                                                                                      true);

        } catch (FactoryException | 

                 TransformException | 

                 NullPointerException | 

                 IllegalArgumentException e) {



                 interiorPointCoordinateChanged = new Coordinate(0,0);

                 System.err.println("Unable to extract feature interior point: ");

                 e.printStackTrace();

        }



        System.out.println("MultilineString interior point lat: " + interiorPointCoordinateChanged.y + " lon: " + interiorPointCoordinateChanged.x);

        return interiorPointCoordinateChanged;  

    }

I apply this on multiple features and sometimes the same code return the correct interior point. Some other times, the method below fails with exception:

*java.lang.IllegalArgumentException: Argument "source" should not be null.

    at org.geotools.geometry.jts.JTS.ensureNonNull(JTS.java:135)

    at org.geotools.geometry.jts.JTS.transform(JTS.java:460)*

Looking into JTS at line 135, I find that name = "source" coming into this method, as null value in object when the exception happens:

private static void ensureNonNull(final String name, final Object object)

            throws IllegalArgumentException {

        if (object == null) {

            throw new IllegalArgumentException(Errors.format(ErrorKeys.NULL_ARGUMENT_$1, name));

        }

    }

I have discovered so, that the exception occurs when the Point coming out from the call:

lineString.getInteriorPoint()

is a POINT EMPTY

Does anyone of you knows why sometimes, getInteriorPoint() returns a POINT EMPTY ? This happens to me only when I try to call getInteriorPoint() on a geometry coming from the interesection between w Polygon and a MultiLineString.

Thanks,

Stefano Falconetti.