code: public double getElevationAt( Direction direction ) {
          switch( direction ) {
          case E:
              return eElev;
          case W:
              return wElev;
          case N:
              return nElev;
          case S:
              return sElev;
          case EN:
              return enElev;
          case NW:
              return nwElev;
          case WS:
              return wsElev;
          case SE:
              return seElev;
          default:
              throw new IllegalArgumentException();
          }
      }
docs: Get the value of the elevation in one of the surrounding direction.
  
  @param direction the {@link Direction}.
  @return the elevation value.