map caching
DESCRIPTION
GISTRANSCRIPT
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Exploring Options for MapExploringOptionsforMapCaching
TileCacheCreation&ManagementPresentedBy:yToddWascher,BusinessDevelopmentManager
04.21.2011
We Visualize Your World
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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
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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
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CachingOverview
What are some benefits of having a cached mapservice?Whataresomebenefitsofhavingacachedmapservice?
LightenBrowserloadh l dLightenServerload
RequestsforsmallimagesratherthandynamicdatarenderingPotentialtoimproveperformance
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CachingTerms&Concepts
SeedingSeeding
Metatiling
Tiling SchemesTilingSchemes
ImageTypes
Transparency
Projections/Reprojection
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CachingTerms&Concepts
SeedingSeeding
Seeding is basically prerendering or dynamically creating map tiles basedSeedingisbasicallypre renderingordynamicallycreatingmaptilesbaseduponadefinedextentorageometry.
Seedingactionscanbescripted,generatedonthefly(userrequests)ormanuallycreated.
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CachingTerms&ConceptsMetatiling
Ametatileconsistsofseveraltilescombinedintoonelargertile.
Pros:
Avoidduplicatingthelabelingoffeaturesthatspanmore than one tilemorethanonetile
UsuallyquickerfortheWMSbackendtogenerateonelargeimageratherthanmanysmallones
Cons:
Sincethemetatileislarger,itisslowertorenderthananyindividualtile
Memoryconsumption
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CachingTerms&Concepts
Tiling SchemesTilingSchemes
Tiling schemes allow for definition of scale levels, tile size and sometimesTilingschemesallowfordefinitionofscalelevels,tilesizeandsometimescoordinatesystem.
SettingtilingschemesforArcGISServervarygreaterthantheotheroptions we will reviewoptionswewillreview.
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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).
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How?
Consuming WMS and chopping it up into tilesConsumingWMSandchoppingitupintotiles
Storedinaccessibledirectorytobereturnedtoclient
Application requests handled by cache utilityApplicationrequestshandledbycacheutility
Projection
Location
Tilesize
Imageformat
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ComparisonofCachingUtilities
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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.
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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.
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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/
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AMatrix
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So,ArcGISServeralreadyhasCachingTools
Singlemapservicefocus
GUI/Geoprocessingoptions
l d fTailoredforesriAPIs
CompactCache
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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.
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UtilizingCachedServices
Web Applications
ArcGIS Desktop
Geoportals/Opendata
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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/
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Thanks!Thanks!Feelfreetoaskanyquestionsorshare
yourowntips.y p
17158744397
1888WeDoGIS