ElevationLayer*
Map::getElevationLayerByName( const std::string& name ) const
{
    Threading::ScopedReadLock( const_cast<Map*>(this)->_mapDataMutex );
    for( ElevationLayerVector::const_iterator i = _elevationLayers.begin(); i != _elevationLayers.end(); ++i )
        if ( i->get()->getName() == name )
            return i->get();
    return 0L;
}

Config
EarthFileSerializer2::serialize( MapNode* input ) const
{
    Config mapConf("map");
    mapConf.set("version", "2");

    if ( !input || !input->getMap() )
        return mapConf;

    Map* map = input->getMap();
    MapFrame mapf( map, Map::ENTIRE_MODEL );

    // the map and node options:
    Config optionsConf = map->getInitialMapOptions().getConfig();
    optionsConf.merge( input->getMapNodeOptions().getConfig() );
    mapConf.add( "options", optionsConf );

    // the layers
    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); ++i )
    {
        ImageLayer* layer = i->get();
        //Config layerConf = layer->getInitialOptions().getConfig();
        Config layerConf = layer->getImageLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getInitialOptions().driver()->getDriver());        
        mapConf.add( "image", layerConf );
    }

    for( ElevationLayerVector::const_iterator i = mapf.elevationLayers().begin(); i != mapf.elevationLayers().end(); ++i )
    {
        ElevationLayer* layer = i->get();
        //Config layerConf = layer->getInitialOptions().getConfig();
        Config layerConf = layer->getElevationLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getInitialOptions().driver()->getDriver());        
        mapConf.add( "elevation", layerConf );
    }

    for( ModelLayerVector::const_iterator i = mapf.modelLayers().begin(); i != mapf.modelLayers().end(); ++i )
    {
        ModelLayer* layer = i->get();
        Config layerConf = layer->getModelLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getModelLayerOptions().driver()->getDriver());
        mapConf.add( "model", layerConf );
    }

    Config ext = input->externalConfig();
    if ( !ext.empty() )
    {
        ext.key() = "external";
        mapConf.add( ext );
    }

    return mapConf;
}

Revision
Map::getElevationLayers( ElevationLayerVector& out_list ) const
{
    out_list.reserve( _elevationLayers.size() );

    Threading::ScopedReadLock lock( const_cast<Map*>(this)->_mapDataMutex );
    for( ElevationLayerVector::const_iterator i = _elevationLayers.begin(); i != _elevationLayers.end(); ++i )
        out_list.push_back( i->get() );

    return _dataModelRevision;
}

void
OSGTerrainEngineNode::postInitialize( const Map* map, const TerrainOptions& options )
{
    TerrainEngineNode::postInitialize( map, options );

    // Initialize the map frames. We need one for the update thread and one for the
    // cull thread. Someday we can detect whether these are actually the same thread
    // (depends on the viewer's threading mode).
    _update_mapf = new MapFrame( map, Map::MASKED_TERRAIN_LAYERS, "osgterrain-update" );
    _cull_mapf   = new MapFrame( map, Map::TERRAIN_LAYERS, "osgterrain-cull" );

    // merge in the custom options:
    _terrainOptions.merge( options );

    // handle an already-established map profile:
    if ( _update_mapf->getProfile() )
    {
        // NOTE: this will initialize the map with the startup layers
        onMapInfoEstablished( MapInfo(map) );
    }

    // populate the terrain with whatever data is in the map to begin with:
    if ( _terrain )
    {
        // update the terrain revision in threaded mode
        if ( _isStreaming )
        {
            static_cast<StreamingTerrainNode*>(_terrain)->updateTaskServiceThreads( *_update_mapf );
        }

        updateTextureCombining();
    }

    // install a layer callback for processing further map actions:
    map->addMapCallback( new OSGTerrainEngineNodeMapCallbackProxy(this) );

    //Attach to all of the existing elevation layers
    ElevationLayerVector elevationLayers;
    map->getElevationLayers( elevationLayers );
    for( ElevationLayerVector::const_iterator i = elevationLayers.begin(); i != elevationLayers.end(); ++i )
    {
        i->get()->addCallback( _elevationCallback.get() );
    }

    //Attach a callback to all of the 

    // register me.
    registerEngine( this );

    // now that we have a map, set up to recompute the bounds
    dirtyBound();
}

bool
OSGTileFactory::hasMoreLevels( Map* map, const TileKey& key )
{
    //Threading::ScopedReadLock lock( map->getMapDataMutex() );

    bool more_levels = false;

    ImageLayerVector imageLayers;
    map->getImageLayers( imageLayers );

    for ( ImageLayerVector::const_iterator i = imageLayers.begin(); i != imageLayers.end(); i++ )
    {
        const ImageLayerOptions& opt = i->get()->getImageLayerOptions();

        if ( !opt.maxLevel().isSet() || key.getLevelOfDetail() < (unsigned int)*opt.maxLevel() )
        {
            more_levels = true;
            break;
        }
    }
    if ( !more_levels )
    {
        ElevationLayerVector elevLayers;
        map->getElevationLayers( elevLayers );

        for( ElevationLayerVector::const_iterator j = elevLayers.begin(); j != elevLayers.end(); j++ )
        {
            const ElevationLayerOptions& opt = j->get()->getElevationLayerOptions();

            if ( !opt.maxLevel().isSet() || key.getLevelOfDetail() < (unsigned int)*opt.maxLevel() )
            //if ( !j->get()->maxLevel().isSet() || key.getLevelOfDetail() < j->get()->maxLevel().get() )
            {
                more_levels = true;
                break;
            }
        }
    }

    return more_levels;
}

bool
MapFrame::isCached( const TileKey& key ) const
{
    //Check to see if the tile will load fast
    // Check the imagery layers
    for( ImageLayerVector::const_iterator i = imageLayers().begin(); i != imageLayers().end(); i++ )
    {   
        //If we're cache only we should be fast
        if (i->get()->isCacheOnly()) continue;

        osg::ref_ptr< TileSource > source = i->get()->getTileSource();
        if (!source.valid()) continue;

        //If the tile is blacklisted, it should also be fast.
        if ( source->getBlacklist()->contains( key.getTileId() ) ) continue;
        //If no data is available on this tile, we'll be fast
        if ( !source->hasData( key ) ) continue;

        if ( !i->get()->isCached( key ) ) return false;
    }

    for( ElevationLayerVector::const_iterator i = elevationLayers().begin(); i != elevationLayers().end(); ++i )
    {
        //If we're cache only we should be fast
        if (i->get()->isCacheOnly()) continue;

        osg::ref_ptr< TileSource > source = i->get()->getTileSource();
        if (!source.valid()) continue;

        //If the tile is blacklisted, it should also be fast.
        if ( source->getBlacklist()->contains( key.getTileId() ) ) continue;
        if ( !source->hasData( key ) ) continue;
        if ( !i->get()->isCached( key ) )
        {
            return false;
        }
    }

    return true;        
}

void
ElevationManager::sync()
{
    if ( _mapf.sync() || _tileSize == 0 || _maxDataLevel == 0 )
    {
        _tileSize = 0;
        _maxDataLevel = 0;

        for( ElevationLayerVector::const_iterator i = _mapf.elevationLayers().begin(); i != _mapf.elevationLayers().end(); ++i )
        {
            // we need the maximum tile size
            int layerTileSize = i->get()->getTileSize();
            if ( layerTileSize > _tileSize )
                _tileSize = layerTileSize;

            // we also need the maximum available data level.
            unsigned int layerMaxDataLevel = i->get()->getMaxDataLevel();
            if ( layerMaxDataLevel > _maxDataLevel )
                _maxDataLevel = layerMaxDataLevel;
        }
    }
}

void
StreamingTerrainNode::updateTaskServiceThreads( const MapFrame& mapf )
{
    //Get the maximum elevation weight
    float elevationWeight = 0.0f;
    for (ElevationLayerVector::const_iterator itr = mapf.elevationLayers().begin(); itr != mapf.elevationLayers().end(); ++itr)
    {
        ElevationLayer* layer = itr->get();
        float w = layer->getElevationLayerOptions().loadingWeight().value();
        if (w > elevationWeight) elevationWeight = w;
    }

    float totalImageWeight = 0.0f;
    for (ImageLayerVector::const_iterator itr = mapf.imageLayers().begin(); itr != mapf.imageLayers().end(); ++itr)
    {
        totalImageWeight += itr->get()->getImageLayerOptions().loadingWeight().value();
    }

    float totalWeight = elevationWeight + totalImageWeight;

    if (elevationWeight > 0.0f)
    {
        //Determine how many threads each layer gets
        int numElevationThreads = (int)osg::round((float)_numLoadingThreads * (elevationWeight / totalWeight ));
        OE_INFO << LC << "Elevation Threads = " << numElevationThreads << std::endl;
        getElevationTaskService()->setNumThreads( numElevationThreads );
    }

    for (ImageLayerVector::const_iterator itr = mapf.imageLayers().begin(); itr != mapf.imageLayers().end(); ++itr)
    {
        const TerrainLayerOptions& opt = itr->get()->getImageLayerOptions();
        int imageThreads = (int)osg::round((float)_numLoadingThreads * (opt.loadingWeight().value() / totalWeight ));
        OE_INFO << LC << "Image Threads for " << itr->get()->getName() << " = " << imageThreads << std::endl;
        getImageryTaskService( itr->get()->getUID() )->setNumThreads( imageThreads );
    }
}

bool
MapFrame::isCached( const TileKey& key ) const
{
    // is there a map cache at all?
    if ( _map->getCache() == 0L )
        return false;

    //Check to see if the tile will load fast
    // Check the imagery layers
    for( ImageLayerVector::const_iterator i = imageLayers().begin(); i != imageLayers().end(); i++ )
    {   
        const ImageLayer* layer = i->get();

        if (!layer->getEnabled())
            continue;

        // If we're cache only we should be fast
        if (layer->isCacheOnly())
            continue;

        // no-cache mode? always slow
        if (layer->isNoCache())
            return false;

        // No tile source? skip it
        osg::ref_ptr< TileSource > source = layer->getTileSource();
        if (!source.valid())
            continue;

        //If the tile is blacklisted, it should also be fast.
        if ( source->getBlacklist()->contains( key ) )
            continue;

        //If no data is available on this tile, we'll be fast
        if ( !source->hasData( key ) )
            continue;

        if ( !layer->isCached(key) )
            return false;
    }

    for( ElevationLayerVector::const_iterator i = elevationLayers().begin(); i != elevationLayers().end(); ++i )
    {
        const ElevationLayer* layer = i->get();

        if (!layer->getEnabled())
            continue;

        //If we're cache only we should be fast
        if (layer->isCacheOnly())
            continue;

        // no-cache mode? always high-latency.
        if (layer->isNoCache())
            return false;

        osg::ref_ptr< TileSource > source = layer->getTileSource();
        if (!source.valid())
            continue;

        //If the tile is blacklisted, it should also be fast.
        if ( source->getBlacklist()->contains( key ) )
            continue;

        if ( !source->hasData( key ) )
            continue;

        if ( !i->get()->isCached( key ) )
            return false;
    }

    return true;
}

void
MPTerrainEngineNode::postInitialize( const Map* map, const TerrainOptions& options )
{
    TerrainEngineNode::postInitialize( map, options );

    // Initialize the map frames. We need one for the update thread and one for the
    // cull thread. Someday we can detect whether these are actually the same thread
    // (depends on the viewer's threading mode).
    _update_mapf = new MapFrame( map, Map::MASKED_TERRAIN_LAYERS, "mp-update" );

    // merge in the custom options:
    _terrainOptions.merge( options );

    // A shared registry for tile nodes in the scene graph. Enable revision tracking
    // if requested in the options. Revision tracking lets the registry notify all
    // live tiles of the current map revision so they can inrementally update
    // themselves if necessary.
    _liveTiles = new TileNodeRegistry("live");
    _liveTiles->setRevisioningEnabled( _terrainOptions.incrementalUpdate() == true );
    _liveTiles->setMapRevision( _update_mapf->getRevision() );

    // set up a registry for quick release:
    if ( _terrainOptions.quickReleaseGLObjects() == true )
    {
        _deadTiles = new TileNodeRegistry("dead");
    }
    
    // initialize the model factory:
    _tileModelFactory = new TileModelFactory(_liveTiles.get(), _terrainOptions );

    // handle an already-established map profile:
    if ( _update_mapf->getProfile() )
    {
        // NOTE: this will initialize the map with the startup layers
        onMapInfoEstablished( MapInfo(map) );
    }

    // install a layer callback for processing further map actions:
    map->addMapCallback( new MPTerrainEngineNodeMapCallbackProxy(this) );

    // Prime with existing layers:
    _batchUpdateInProgress = true;

    ElevationLayerVector elevationLayers;
    map->getElevationLayers( elevationLayers );
    for( ElevationLayerVector::const_iterator i = elevationLayers.begin(); i != elevationLayers.end(); ++i )
        addElevationLayer( i->get() );

    ImageLayerVector imageLayers;
    map->getImageLayers( imageLayers );
    for( ImageLayerVector::iterator i = imageLayers.begin(); i != imageLayers.end(); ++i )
        addImageLayer( i->get() );

    _batchUpdateInProgress = false;

    // install some terrain-wide uniforms
    this->getOrCreateStateSet()->getOrCreateUniform(
        "oe_min_tile_range_factor",
        osg::Uniform::FLOAT)->set( *_terrainOptions.minTileRangeFactor() );

    // set up the initial shaders
    updateState();

    // register this instance to the osgDB plugin can find it.
    registerEngine( this );

    // now that we have a map, set up to recompute the bounds
    dirtyBound();

    OE_INFO << LC << "Edge normalization is " << (_terrainOptions.normalizeEdges() == true? "ON" : "OFF") << std::endl;
}

bool
Map::sync( MapFrame& frame ) const
{
    bool result = false;

    if ( frame._mapDataModelRevision != _dataModelRevision || !frame._initialized )
    {
        // hold the read lock while copying the layer lists.
        Threading::ScopedReadLock lock( const_cast<Map*>(this)->_mapDataMutex );

        if ( frame._parts & IMAGE_LAYERS )
        {
            if ( !frame._initialized )
                frame._imageLayers.reserve( _imageLayers.size() );
            frame._imageLayers.clear();
            if ( frame._copyValidDataOnly )
            {
                for( ImageLayerVector::const_iterator i = _imageLayers.begin(); i != _imageLayers.end(); ++i )
                    if ( i->get()->getProfile() )
                        frame._imageLayers.push_back( i->get() );
            }
            else
                std::copy( _imageLayers.begin(), _imageLayers.end(), std::back_inserter(frame._imageLayers) );
        }

        if ( frame._parts & ELEVATION_LAYERS )
        {
            if ( !frame._initialized )
                frame._elevationLayers.reserve( _elevationLayers.size() );
            frame._elevationLayers.clear();
            if ( frame._copyValidDataOnly )
            {
                for( ElevationLayerVector::const_iterator i = _elevationLayers.begin(); i != _elevationLayers.end(); ++i )
                    if ( i->get()->getProfile() )
                        frame._elevationLayers.push_back( i->get() );
            }
            else
                std::copy( _elevationLayers.begin(), _elevationLayers.end(), std::back_inserter(frame._elevationLayers) );
        }

        if ( frame._parts & MODEL_LAYERS )
        {
            if ( !frame._initialized )
                frame._modelLayers.reserve( _modelLayers.size() );
            frame._modelLayers.clear();
            std::copy( _modelLayers.begin(), _modelLayers.end(), std::back_inserter(frame._modelLayers) );
        }

        if ( frame._parts & MASK_LAYERS )
        {
          if ( !frame._initialized )
              frame._maskLayers.reserve( _terrainMaskLayers.size() );
          frame._maskLayers.clear();
          std::copy( _terrainMaskLayers.begin(), _terrainMaskLayers.end(), std::back_inserter(frame._maskLayers) );
        }

        // sync the revision numbers.
        frame._initialized = true;
        frame._mapDataModelRevision = _dataModelRevision;
            
        result = true;
    }    
    return result;
}

bool
MapFrame::isCached( const osgEarth::TileKey& key ) const
{
    const Profile* mapProfile = getProfile();

    //Check the imagery layers
    for( ImageLayerVector::const_iterator i = imageLayers().begin(); i != imageLayers().end(); i++ )
    {
        ImageLayer* layer = i->get();
        osg::ref_ptr< Cache > cache = layer->getCache();

        if ( !cache.valid() || !layer->getProfile() ) 
            return false;

        std::vector< TileKey > keys;

        if ( mapProfile->isEquivalentTo( layer->getProfile() ) )
        {
            keys.push_back( key );
        }
        else
        {
            layer->getProfile()->getIntersectingTiles( key, keys );
        }

        for (unsigned int j = 0; j < keys.size(); ++j)
        {
            if ( layer->isKeyValid( keys[j] ) )
            {
                if ( !cache->isCached( keys[j], layer->getCacheSpec() ) )
                {
                    return false;
                }
            }
        }
    }

    for( ElevationLayerVector::const_iterator i = elevationLayers().begin(); i != elevationLayers().end(); ++i )
    {
        ElevationLayer* layer = i->get();
        osg::ref_ptr< Cache > cache = layer->getCache();

        if ( !cache.valid() || !layer->getProfile() )
            return false;

        std::vector<TileKey> keys;

        if ( mapProfile->isEquivalentTo( layer->getProfile() ) )
        {
            keys.push_back( key );
        }
        else
        {
            layer->getProfile()->getIntersectingTiles( key, keys );
        }

        for (unsigned int j = 0; j < keys.size(); ++j)
        {
            if ( layer->isKeyValid( keys[j] ) )
            {
                if ( !cache->isCached( keys[j], layer->getCacheSpec() ) )
                {
                    return false;
                }
            }
        }
    }
    return true;
}

void
MPTerrainEngineNode::postInitialize( const Map* map, const TerrainOptions& options )
{
    TerrainEngineNode::postInitialize( map, options );

    // Initialize the map frames. We need one for the update thread and one for the
    // cull thread. Someday we can detect whether these are actually the same thread
    // (depends on the viewer's threading mode).
    _update_mapf = new MapFrame( map, Map::MASKED_TERRAIN_LAYERS, "mp-update" );

    // merge in the custom options:
    _terrainOptions.merge( options );

    // a shared registry for tile nodes in the scene graph.
    _liveTiles = new TileNodeRegistry("live");

    // set up a registry for quick release:
    if ( _terrainOptions.quickReleaseGLObjects() == true )
    {
        _deadTiles = new TileNodeRegistry("dead");
    }
    
    // initialize the model factory:
    _tileModelFactory = new TileModelFactory(getMap(), _liveTiles.get(), _terrainOptions );


    // handle an already-established map profile:
    if ( _update_mapf->getProfile() )
    {
        // NOTE: this will initialize the map with the startup layers
        onMapInfoEstablished( MapInfo(map) );
    }

    // populate the terrain with whatever data is in the map to begin with:
    if ( _terrain )
    {
        // reserve a GPU image unit and two attribute indexes.
        this->getTextureCompositor()->reserveTextureImageUnit( _primaryUnit );
        this->getTextureCompositor()->reserveTextureImageUnit( _secondaryUnit );

        //this->getTextureCompositor()->reserveAttribIndex( _attribIndex1 );
        //this->getTextureCompositor()->reserveAttribIndex( _attribIndex2 );
    }

    // install a layer callback for processing further map actions:
    map->addMapCallback( new MPTerrainEngineNodeMapCallbackProxy(this) );

    // Prime with existing layers:
    _batchUpdateInProgress = true;

    ElevationLayerVector elevationLayers;
    map->getElevationLayers( elevationLayers );
    for( ElevationLayerVector::const_iterator i = elevationLayers.begin(); i != elevationLayers.end(); ++i )
        addElevationLayer( i->get() );

    ImageLayerVector imageLayers;
    map->getImageLayers( imageLayers );
    for( ImageLayerVector::iterator i = imageLayers.begin(); i != imageLayers.end(); ++i )
        addImageLayer( i->get() );

    _batchUpdateInProgress = false;
    //{
    //    i->get()->addCallback( _elevationCallback.get() );
    //}

    // install some terrain-wide uniforms
    this->getOrCreateStateSet()->getOrCreateUniform(
        "oe_min_tile_range_factor",
        osg::Uniform::FLOAT)->set( *_terrainOptions.minTileRangeFactor() );

    // set up the initial shaders
    updateShaders();

    // register this instance to the osgDB plugin can find it.
    registerEngine( this );

    // now that we have a map, set up to recompute the bounds
    dirtyBound();
}

Config
EarthFileSerializer2::serialize(const MapNode* input, const std::string& referrer) const
{
    Config mapConf("map");
    mapConf.set("version", "2");

    if ( !input || !input->getMap() )
        return mapConf; 

    const Map* map = input->getMap();
    MapFrame mapf( map, Map::ENTIRE_MODEL );

    // the map and node options:
    Config optionsConf = map->getInitialMapOptions().getConfig();
    optionsConf.merge( input->getMapNodeOptions().getConfig() );
    mapConf.add( "options", optionsConf );

    // the layers
    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); ++i )
    {
        ImageLayer* layer = i->get();
        //Config layerConf = layer->getInitialOptions().getConfig();
        Config layerConf = layer->getImageLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getInitialOptions().driver()->getDriver());        
        mapConf.add( "image", layerConf );
    }

    for( ElevationLayerVector::const_iterator i = mapf.elevationLayers().begin(); i != mapf.elevationLayers().end(); ++i )
    {
        ElevationLayer* layer = i->get();
        //Config layerConf = layer->getInitialOptions().getConfig();
        Config layerConf = layer->getElevationLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getInitialOptions().driver()->getDriver());        
        mapConf.add( "elevation", layerConf );
    }

    for( ModelLayerVector::const_iterator i = mapf.modelLayers().begin(); i != mapf.modelLayers().end(); ++i )
    {
        ModelLayer* layer = i->get();
        Config layerConf = layer->getModelLayerOptions().getConfig();
        layerConf.set("name", layer->getName());
        layerConf.set("driver", layer->getModelLayerOptions().driver()->getDriver());
        mapConf.add( "model", layerConf );
    }

    Config ext = input->externalConfig();
    if ( !ext.empty() )
    {
        ext.key() = "extensions";
        mapConf.add( ext );
    }

#if 1 // removed until it can be debugged.
    // Re-write pathnames in the Config so they are relative to the new referrer.
    if ( _rewritePaths && !referrer.empty() )
    {
        RewritePaths rewritePaths( referrer );
        rewritePaths.setRewriteAbsolutePaths( _rewriteAbsolutePaths );
        rewritePaths.apply( mapConf );
    }
#endif

    return mapConf;
}

void CacheSeed::seed( Map* map )
{
    if ( !map->getCache() )
    {
        OE_WARN << LC << "Warning: No cache defined; aborting." << std::endl;
        return;
    }

    std::vector<TileKey> keys;
    map->getProfile()->getRootKeys(keys);

    //Add the map's entire extent if we don't have one specified.
    if (_extents.empty())
    {
        addExtent( map->getProfile()->getExtent() );
    }

    bool hasCaches = false;
    int src_min_level = INT_MAX;
    unsigned int src_max_level = 0;

    MapFrame mapf( map, Map::TERRAIN_LAYERS, "CacheSeed::seed" );

    //Assumes the the TileSource will perform the caching for us when we call createImage
    for( ImageLayerVector::const_iterator i = mapf.imageLayers().begin(); i != mapf.imageLayers().end(); i++ )
    {
        ImageLayer* layer = i->get();
        TileSource* src   = layer->getTileSource();

        const ImageLayerOptions& opt = layer->getImageLayerOptions();

        if ( layer->isCacheOnly() )
        {
            OE_WARN << LC << "Warning: Layer \"" << layer->getName() << "\" is set to cache-only; skipping." << std::endl;
        }
        else if ( !src )
        {
            OE_WARN << "Warning: Layer \"" << layer->getName() << "\" could not create TileSource; skipping." << std::endl;
        }
        //else if ( src->getCachePolicyHint(0L) == CachePolicy::NO_CACHE )
        //{
        //    OE_WARN << LC << "Warning: Layer \"" << layer->getName() << "\" does not support seeding; skipping." << std::endl;
        //}
        else if ( !layer->getCache() )
        {
            OE_WARN << LC << "Notice: Layer \"" << layer->getName() << "\" has no cache defined; skipping." << std::endl;
        }
        else
        {
            hasCaches = true;

            if (opt.minLevel().isSet() && (int)opt.minLevel().get() < src_min_level)
                src_min_level = opt.minLevel().get();
            if (opt.maxLevel().isSet() && opt.maxLevel().get() > src_max_level)
                src_max_level = opt.maxLevel().get();
        }
    }

    for( ElevationLayerVector::const_iterator i = mapf.elevationLayers().begin(); i != mapf.elevationLayers().end(); i++ )
    {
        ElevationLayer* layer = i->get();
        TileSource*     src   = layer->getTileSource();
        const ElevationLayerOptions& opt = layer->getElevationLayerOptions();

        if ( layer->isCacheOnly() )
        {
            OE_WARN << LC << "Warning: Layer \"" << layer->getName() << "\" is set to cache-only; skipping." << std::endl;
        }
        else if (!src)
        {
            OE_WARN << "Warning: Layer \"" << layer->getName() << "\" could not create TileSource; skipping." << std::endl;
        }
        //else if ( src->getCachePolicyHint(0L) == CachePolicy::NO_CACHE )
        //{
        //    OE_WARN << LC << "Warning: Layer \"" << layer->getName() << "\" does not support seeding; skipping." << std::endl;
        //}
        else if ( !layer->getCache() )
        {
            OE_WARN << LC << "Notice: Layer \"" << layer->getName() << "\" has no cache defined; skipping." << std::endl;
        }
        else
        {
            hasCaches = true;

            if (opt.minLevel().isSet() && (int)opt.minLevel().get() < src_min_level)
                src_min_level = opt.minLevel().get();
            if (opt.maxLevel().isSet() && opt.maxLevel().get() > src_max_level)
                src_max_level = opt.maxLevel().get();
        }
    }

    if ( !hasCaches )
    {
        OE_WARN << LC << "There are either no caches defined in the map, or no sources to cache; aborting." << std::endl;
        return;
    }

    if ( src_max_level > 0 && src_max_level < _maxLevel )
    {
        _maxLevel = src_max_level;
//.........这里部分代码省略.........

bool
ElevationLayerVector::createHeightField(const TileKey&                  key,
                                        bool                            fallback,
                                        const Profile*                  haeProfile,
                                        ElevationInterpolation          interpolation,
                                        ElevationSamplePolicy           samplePolicy,
                                        osg::ref_ptr<osg::HeightField>& out_result,
                                        bool*                           out_isFallback,
                                        ProgressCallback*               progress )  const
{        
    unsigned lowestLOD = key.getLevelOfDetail();
    bool hfInitialized = false;

    //Get a HeightField for each of the enabled layers
    GeoHeightFieldVector heightFields;

    //The number of fallback heightfields we have
    int numFallbacks = 0;

    //Default to being fallback data.
    if ( out_isFallback )
    {
        *out_isFallback = true;
    }

    // if the caller provided an "HAE map profile", he wants an HAE elevation grid even if
    // the map profile has a vertical datum. This is the usual case when building the 3D
    // terrain, for example. Construct a temporary key that doesn't have the vertical
    // datum info and use that to query the elevation data.
    TileKey keyToUse = key;
    if ( haeProfile )
    {
        keyToUse = TileKey(key.getLevelOfDetail(), key.getTileX(), key.getTileY(), haeProfile );
    }

    // Generate a heightfield for each elevation layer.

    unsigned defElevSize = 8;

    for( ElevationLayerVector::const_iterator i = this->begin(); i != this->end(); i++ )
    {
        ElevationLayer* layer = i->get();
        if ( layer->getVisible() )
        {
            GeoHeightField geoHF = layer->createHeightField( keyToUse, progress );

            // if "fallback" is set, try to fall back on lower LODs.
            if ( !geoHF.valid() && fallback )
            {
                TileKey hf_key = keyToUse.createParentKey();

                while ( hf_key.valid() && !geoHF.valid() )
                {
                    geoHF = layer->createHeightField( hf_key, progress );
                    if ( !geoHF.valid() )
                        hf_key = hf_key.createParentKey();
                }

                if ( geoHF.valid() )
                {
                    if ( hf_key.getLevelOfDetail() < lowestLOD )
                        lowestLOD = hf_key.getLevelOfDetail();

                    //This HeightField is fallback data, so increment the count.
                    numFallbacks++;
                }
            }

            if ( geoHF.valid() )
            {
                heightFields.push_back( geoHF );
            }
        }
    }

    //If any of the layers produced valid data then it's not considered a fallback
    if ( out_isFallback )
    {
        *out_isFallback = (numFallbacks == heightFields.size());
        //OE_NOTICE << "Num fallbacks=" << numFallbacks << " numHeightFields=" << heightFields.size() << " is fallback " << *out_isFallback << std::endl;
    }   

    if ( heightFields.size() == 0 )
    {            
        //If we got no heightfields but were requested to fallback, create an empty heightfield.
        if ( fallback )
        {
            out_result = HeightFieldUtils::createReferenceHeightField( keyToUse.getExtent(), defElevSize, defElevSize );                
            return true;
        }
        else
        {
            //We weren't requested to fallback so just return.
            return false;
        }
    }

    else if (heightFields.size() == 1)
    {
        if ( lowestLOD == key.getLevelOfDetail() )
//.........这里部分代码省略.........

void
MPTerrainEngineNode::postInitialize( const Map* map, const TerrainOptions& options )
{
    TerrainEngineNode::postInitialize( map, options );

    // Initialize the map frames. We need one for the update thread and one for the
    // cull thread. Someday we can detect whether these are actually the same thread
    // (depends on the viewer's threading mode).
    _update_mapf = new MapFrame( map, Map::ENTIRE_MODEL, "mp-update" );

    // merge in the custom options:
    _terrainOptions.merge( options );

    // A shared registry for tile nodes in the scene graph. Enable revision tracking
    // if requested in the options. Revision tracking lets the registry notify all
    // live tiles of the current map revision so they can inrementally update
    // themselves if necessary.
    _liveTiles = new TileNodeRegistry("live");
    _liveTiles->setRevisioningEnabled( _terrainOptions.incrementalUpdate() == true );
    _liveTiles->setMapRevision( _update_mapf->getRevision() );

    // set up a registry for quick release:
    if ( _terrainOptions.quickReleaseGLObjects() == true )
    {
        _deadTiles = new TileNodeRegistry("dead");
    }

    // reserve GPU resources. Must do this before initializing the model factory.
    if ( _primaryUnit < 0 )
    {
        getResources()->reserveTextureImageUnit( _primaryUnit, "MP Engine Primary" );
    }

    // "Secondary" unit serves double duty; it's used for parent textures BUT it's also
    // used at the "slot" for the tile coordinates.
    if ( _secondaryUnit < 0 )
    {
        getResources()->reserveTextureImageUnit( _secondaryUnit, "MP Engine Secondary" );
    }
    
    // initialize the model factory:
    _tileModelFactory = new TileModelFactory(_liveTiles.get(), _terrainOptions, this);

    // handle an already-established map profile:
    if ( _update_mapf->getProfile() )
    {
        // NOTE: this will initialize the map with the startup layers
        onMapInfoEstablished( MapInfo(map) );
    }

    // install a layer callback for processing further map actions:
    map->addMapCallback( new MPTerrainEngineNodeMapCallbackProxy(this) );

    // Prime with existing layers:
    _batchUpdateInProgress = true;

    ElevationLayerVector elevationLayers;
    map->getElevationLayers( elevationLayers );
    for( ElevationLayerVector::const_iterator i = elevationLayers.begin(); i != elevationLayers.end(); ++i )
        addElevationLayer( i->get() );

    ImageLayerVector imageLayers;
    map->getImageLayers( imageLayers );
    for( ImageLayerVector::iterator i = imageLayers.begin(); i != imageLayers.end(); ++i )
        addImageLayer( i->get() );

    _batchUpdateInProgress = false;

    // register this instance to the osgDB plugin can find it.
    registerEngine( this );

    // set up the initial shaders and reserve the texture image units.
    updateState();

    // now that we have a map, set up to recompute the bounds
    dirtyBound();

    OE_INFO << LC << "Edge normalization is " << (_terrainOptions.normalizeEdges() == true? "ON" : "OFF") << std::endl;
}

void
RexTerrainEngineNode::postInitialize( const Map* map, const TerrainOptions& options )
{
    TerrainEngineNode::postInitialize( map, options );

    // Initialize the map frames. We need one for the update thread and one for the
    // cull thread. Someday we can detect whether these are actually the same thread
    // (depends on the viewer's threading mode).
    _update_mapf = new MapFrame( map, Map::ENTIRE_MODEL );

    // merge in the custom options:
    _terrainOptions.merge( options );

    // morphing imagery LODs requires we bind parent textures to their own unit.
    if ( _terrainOptions.morphImagery() == true )
    {
        _requireParentTextures = true;
    }

    // if the envvar for tile expiration is set, overide the options setting
    const char* val = ::getenv("OSGEARTH_EXPIRATION_THRESHOLD");
    if ( val )
    {
        _terrainOptions.expirationThreshold() = as<unsigned>(val, _terrainOptions.expirationThreshold().get());
        OE_INFO << LC << "Expiration threshold set by env var = " << _terrainOptions.expirationThreshold().get() << "\n";
    }

    // if the envvar for hires prioritization is set, override the options setting
    const char* hiresFirst = ::getenv("OSGEARTH_HIGH_RES_FIRST");
    if ( hiresFirst )
    {
        _terrainOptions.highResolutionFirst() = true;
    }

    // check for normal map generation (required for lighting).
    if ( _terrainOptions.normalMaps() == true )
    {
        this->_requireNormalTextures = true;
    }

    // A shared registry for tile nodes in the scene graph. Enable revision tracking
    // if requested in the options. Revision tracking lets the registry notify all
    // live tiles of the current map revision so they can inrementally update
    // themselves if necessary.
    _liveTiles = new TileNodeRegistry("live");
    _liveTiles->setMapRevision( _update_mapf->getRevision() );

    if ( _terrainOptions.quickReleaseGLObjects() == true )
    {
        _deadTiles = new TileNodeRegistry("dead");
        _quickReleaseInstalled = false;
        ADJUST_UPDATE_TRAV_COUNT( this, +1 );
    }

    // A shared geometry pool.
    if ( ::getenv("OSGEARTH_REX_NO_POOL") == 0L )
    {
        _geometryPool = new GeometryPool( _terrainOptions );
    }

    // Make a tile loader
    PagerLoader* loader = new PagerLoader( this );
    loader->setMergesPerFrame( _terrainOptions.mergesPerFrame().get() );

    _loader = loader;
    //_loader = new SimpleLoader();
    this->addChild( _loader.get() );
    
    // handle an already-established map profile:
    MapInfo mapInfo( map );
    if ( _update_mapf->g