code: public GeometryFactory getGeometryFactory() {
  		if (null == geometryFactory) {
  			if (0 == srid) {
  				throw new IllegalArgumentException("srid needs to be set on MapModel to obtain GeometryFactory");
  			}
  			geometryFactory = new GeometryFactory(srid, -1); // @todo precision is not yet implemented
  		}
  		return geometryFactory;
  	}
docs: Return a factory for geometries that is suited perfectly for geometries within this model. The SRID and precision
  will for the factory will be correct.
  
  @return geometry factory