int loadMapData(osg::Group* root) {
    // Load the map
    osg::Node* map = osgDB::readNodeFile("/home/dien/Desktop/osgearth/tests/BacBo/Map.earth");
    // Find the MapNode
    osgEarth::MapNode* mapNode = osgEarth::MapNode::get( map );
    root->addChild( mapNode );

    //Load topograph
    osg::Node* data = osgDB::readNodeFile("/home/dien/Desktop/osgearth/tests/BacBo/n20_e102_3arc_v2.earth");
    osgEarth::MapNode* mapData = osgEarth::MapNode::get( data );
    if (!mapData)
    {
        OE_NOTICE << "Could not find MapNode " << std::endl;
        return 0;
    }
    root->addChild( mapData );

    //Load topograph2
    osg::Node* data2 = osgDB::readNodeFile("/home/dien/Desktop/osgearth/tests/BacBo/n20_e103_3arc_v2.earth");
    osgEarth::MapNode* mapData2 = osgEarth::MapNode::get( data2 );
    if (!mapData2)
    {
        OE_NOTICE << "Could not find MapNode " << std::endl;
        return 0;
    }
    root->addChild( mapData2 );

    return 1;
}

//main
//    osg::Group* root = new osg::Group();