code: Envelope2D getEnvelope2D() {
  		Envelope2D env = new Envelope2D();
  		env.setEmpty();
  		VertexIterator vert_iter = queryVertexIterator();
  		Point2D pt = new Point2D();
  		boolean b_first = true;
  		for (int ivertex = vert_iter.next(); ivertex != -1; ivertex = vert_iter
  				.next()) {
  			getXY(ivertex, pt);
  			if (b_first)
  				env.merge(pt.x, pt.y);
  			else
  				env.mergeNE(pt.x, pt.y);
  
  			b_first = false;
  		}
  
  		return env;
  	}
docs: Returns envelope of all coordinates.