private void addToOpenset(final OsmPath path) {
        if (path.cost >= 0) {
            openSet.add(path.cost + (int) (path.airdistance * airDistanceCostFactor), path);
        }
    }
find the elevation type for position
to determine the filter value

@param n  the point
@return  the filter value for 1sec / 3sec elevation source
main/src/main/java/cgeo/geocaching/brouter/core/RoutingEngine.java