MAP CACHING

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Text of MAP CACHING

  • Exploring Options for MapExploringOptionsforMapCaching

    TileCacheCreation&ManagementPresentedBy:yToddWascher,BusinessDevelopmentManager

    04.21.2011

    We Visualize Your World

  • Whachutalkinbout?

    Whatwellcoverwiththissession:

    A O i AnOverview

    CachingExplained(briefly)

    General Benefits of Map Caching GeneralBenefitsofMapCaching

    SomeCachingTermsandConcepts

    A Comparison of Available ToolsAComparisonofAvailableTools

    Mapproxy,Tilecache,GeoWebCache,ArcGISServer

    Functionality&CapabilitiesofEachy p

    Summary&Conclusion

    ChoosingtheRightToolfortheJob

    ConsumingandUtilizingCachedMapservices

  • CachingOverviewWell,whatismapcaching?

    What types of things can I cache?WhattypesofthingscanIcache?

    GotanyExamples?

    http://mt0.google.com/vt/lyrs=t@126,r@145&hl=en&x=2018&y=2949&z=13&s=Gal

    http://ecn.t2.tiles.virtualearth.net/tiles/r0213331100212?g=637&mkt=en-us&lbl=l1&stl=h&shading=hill&n=z

    http://services.arcgisonline.com/ArcGIS/rest/services/World_Topo_Map/MapServer/tile/13/2949/2018

  • CachingOverview

    What are some benefits of having a cached mapservice?Whataresomebenefitsofhavingacachedmapservice?

    LightenBrowserloadh l dLightenServerload

    RequestsforsmallimagesratherthandynamicdatarenderingPotentialtoimproveperformance

  • CachingTerms&Concepts

    SeedingSeeding

    Metatiling

    Tiling SchemesTilingSchemes

    ImageTypes

    Transparency

    Projections/Reprojection

  • CachingTerms&Concepts

    SeedingSeeding

    Seeding is basically prerendering or dynamically creating map tiles basedSeedingisbasicallypre renderingordynamicallycreatingmaptilesbaseduponadefinedextentorageometry.

    Seedingactionscanbescripted,generatedonthefly(userrequests)ormanuallycreated.

  • CachingTerms&ConceptsMetatiling

    Ametatileconsistsofseveraltilescombinedintoonelargertile.

    Pros:

    Avoidduplicatingthelabelingoffeaturesthatspanmore than one tilemorethanonetile

    UsuallyquickerfortheWMSbackendtogenerateonelargeimageratherthanmanysmallones

    Cons:

    Sincethemetatileislarger,itisslowertorenderthananyindividualtile

    Memoryconsumption

  • CachingTerms&Concepts

    Tiling SchemesTilingSchemes

    Tiling schemes allow for definition of scale levels, tile size and sometimesTilingschemesallowfordefinitionofscalelevels,tilesizeandsometimescoordinatesystem.

    SettingtilingschemesforArcGISServervarygreaterthantheotheroptions we will reviewoptionswewillreview.

  • CachingTerms&Concepts

    Image TypesImageTypes

    Cachedmaptilescanbecreated/requestedindifferentimageformats.Mostcommonly.pngfortransparencyand.jpegforimagery.

    Transparency

    Transparencyisusedforoverlayingtilesontopofothertilesandforsliding/transitioning effects Supported with pngsliding/transitioningeffects.Supportedwith.png.

    AlsoparameterinWMSrequest.

    Projections / ReprojectionProjections/Reprojection

    Mostcachesarecreatedinadefinedprojection,butsomeutilitiescanreprojecttiles(mapproxy).

  • How?

    Consuming WMS and chopping it up into tilesConsumingWMSandchoppingitupintotiles

    Storedinaccessibledirectorytobereturnedtoclient

    Application requests handled by cache utilityApplicationrequestshandledbycacheutility

    Projection

    Location

    Tilesize

    Imageformat

  • ComparisonofCachingUtilities

  • MapProxy

    MapProxyisanopensourceproxyforgeospatialdata.Itcaches,acceleratesandtransforms data from existing map services and serves any desktop or web GIStransformsdatafromexistingmapservicesandservesanydesktoporwebGISclient.

    MapProxyworkslikeasimpletilecache,butalsooffersmanynewandinnovativefeatureslikefullsupportforWMSclients.

    MapProxyisanopensourcetechnologyusedtocreateandserveupmapcaches.Itis a middleman between existing web map servers (like MapServer or GeoServer)isamiddle manbetweenexistingwebmapservers(likeMapServerorGeoServer)andwebmapclientssuchasOpenLayersandGoogleEarth.

  • TileCache

    TileCacheisanimplementationofaWMSCcompliantservermadeavailableundertheBSD(Berkeley Software Distribution) licensebyMetaCarta.

    TileCacheprovidesaPythonbasedWMSC/TMSserver,withpluggablecachingmechanisms and rendering backends In the simplest use case TileCache requiresmechanismsandrenderingbackends.Inthesimplestusecase,TileCacherequiresonlywriteaccesstoadisk,theabilitytorunPythonCGIscripts,andaWMSyouwanttobecached.Withtheseresources,youcancreateyourownlocaldiskbasedcacheofanyWMSserver,andusetheresultinanyWMSCsupportingclient,likeOpenLayers,oranyTMSsupportingclient,likeOpenLayersandworldKit.

  • GeoWebCache

    GeoWebCache is a Java web application used to cache map tiles coming from a variety of sources such as OGC Web Map Service (WMS) coming from a variety of sources such as OGC Web Map Service (WMS). It implements various service interfaces (such as WMS-C, WMTS, TMS, Google Maps KML, Virtual Earth) in order to accelerate and optimize map image delivery. It can also recombine tiles to work with regular WMS clients.

    http://geowebcache.org/

  • AMatrix

  • So,ArcGISServeralreadyhasCachingTools

    Singlemapservicefocus

    GUI/Geoprocessingoptions

    l d fTailoredforesriAPIs

    CompactCache

  • ChoosetheRightToolfortheJob

    All caching utilities are basically reading a mapservice taking a snapshot of it andAllcachingutilitiesarebasicallyreadingamapservice,takingasnapshotofitandcuttingitupintotilesdefinedbytheuser/tool.Oncethetilesarecreated,theyarestoredinadirectorystructuresimilarto:

    CachedirectoryNameofserviceScalelevelsRowRowColumnImage

    Thi h li h l b d h l i d i h j b b i ll ilThismaychangeslightlybasedonwhattoolisdoingthejob,buttypicallytilesareslicedandstoredaroundthegridbasedsystemoflevel,row,column.

  • UtilizingCachedServices

    Web Applications

    ArcGIS Desktop

    Geoportals/Opendata

  • ResourcesLinks!

    http://mappro org/http://mapproxy.org/

    http://tilecache.org/

    http://geowebcache.org/

    http://help.arcgis.com/en/arcgisserver/10.0/help/arcgis_server_dotnet_help/index html#/What is map caching/00930000006m000000//index.html#/What_is_map_caching/00930000006m000000/

  • Thanks!Thanks!Feelfreetoaskanyquestionsorshare

    yourowntips.y p

    17158744397

    1888WeDoGIS

    Todd.Wascher@adc4gis.com