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DESCRIPTION
Bent Hagemark (Google)This session will cover advanced techniques in KML for displaying data and creating dynamic presentations. We'll show how to to use Region to display very large datasets without clutter and without compromising performance. We'll also look at how time features can be used to add animation effects and how NetworkLinkControl and Update can be used to make dynamic KML presentations.Watch a video at http://www.bestechvideos.com/2008/09/07/google-i-o-2008-advanced-kml
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Advanced KML
Bent HagemarkMay 29, 2008
Overview
OGC StandardKML ArchitectureAdvanced featuresFuture enhancement
OGC Standard
OGC KML 2.2
April 14, 2008Standard: 07-147r2Abstract Test Suite: 07-134r2100% "Google" KML 2.2 compatiblexmlns="http://www.opengis.net/kml/2.2"
OGC KML 2.2
www.opengeospatial.org/standards/kmlschemas.opengis.net/kml/2.2.0/ogckml22.xsdcode.google.com/apis/kmlcode.google.com/apis/kml/documentation/kmlreference.html
KML Architecture
KML Architecture
ObjectFeatureGeometryStyleLinkExtension mechanism
Object
most complex elementsid="ID"targetId="ID" for UpdateAbstractXxxObjectExtensionGroupkml:AbstractObjectGroup (8.1)
Feature
left panel entry: name, snippet, visibilityballoonstyleviewpoint, flyTocustom datakml:AbstractFeatureGroup (9.1)
Feature: concrete elements
PlacemarkNetworkLinkContainer: Document, FolderOverlay: GroundOverlay, PhotoOverlay, ScreenOverlay
Geometry
2d or 3dextrudetessellatekml:AbstractGeometryGroup (10.1)
Geometry: concrete elements
Point (icon)LineString, LinearRingPolygonModel (textured 3d)MultiGeometry
Style
shared style (6.4)inline stylestyle resolutionkml:AbstractStyleSelectorGroup (12.1)
Style: concrete elements
StyleStyleMapstyleUrlSubStyle: BalloonStyle, ListStyle, ColorStyleColorStyle: IconStyle, LabelStyle, LineStyle, PolyStyle
Link
hrefnetwork-shared stylenetwork-shared schemaimages, 3d models, more KMLballoonascription
Link: concrete elements
NetworkLink/Link/hrefOverlay/Icon/hrefModel/Link/hrefstyleUrlschemaUrlhtml:img src="..."html:a href="..."atom:link
Extension mechanism
ExtendedData/DataDocument/Schema, ExtendedData/SchemaDataExtendedData/XMLXSD extension mechanism
XML and JavaScript
same model (same system!)code.google.com/apis/kml/documentationcode.google.com/apis/earth
Advanced features
Review: Basic features
PlacemarkOverlayFolderStyleNetworkLink
Advanced features
RegionTimeUpdateExtendedData
Region
Feature LODvisibility transitionsmillions of pointsSuperOverlay
Region: any Feature
Placemark: visibilityNetworkLink: fetchOverlay: fetch of image and visibilityDocument/Folder: cascade
Region: simple effects
simple Lodpop in and outfadeclean swap with fade
Region: Example 1: simple Lod
<Placemark> <Region> <Lod> <minLodPixels>128</minLodPixels> </Lod> <LatLonAltBox>...</LatLonAltBox> </Region>
<Point>...</Point>
</Placemark>
Region: Example 2: pop in and out
<Placemark> <Region> <Lod> <minLodPixels>128</minLodPixels> <maxLodPixels>512</maxLodPixels> </Lod> <LatLonAltBox>...</LatLonAltBox> </Region>
<Point>...</Point>
</Placemark>
Region: Example 3: clean swap
<Placemark id="coarse"> <Region> <Lod> <!-- minLodPixels defaults to 0 --> <maxLodPixels>256</maxLodPixels> </Lod> <LatLonAltBox>...</LatLonAltBox> </Region>
<Point>...</Point> <!-- "come look here" -->
</Placemark>
Region: Example 3: clean swap
<Placemark id="fine"> <Region> <Lod> <minLodPixels>256</minLodPixels> </Lod> <!-- maxLodPixels defaults to -1 "infinite" --> <LatLonAltBox>...</LatLonAltBox> </Region>
<Polygon>...</Polygon> <!-- more detail -->
</Placemark>
Region: NetworkLink
<NetworkLink> <Region> <Lod> <minLodPixels>256</minLodPixels> </Lod> <LatLonAltBox>...</LatLonAltBox> </Region> <Link> <href>load-when-viewer-close-enough.kml</href> <viewRefreshMode>onRegion</viewRefreshMode> </Link></NetworkLink>
Region: "RbNL" and tools
cascade of Region-based NetworkLinksKML Layerscode.google.com/p/regionator
csvregionator.py - CSV -> RbNLplacemarks.py - KML -> RbNLchecklinks.py - walks RbNLcheckregions.py - checks RbNL Regions
code.google.com/p/libkml
Region: "RbNL" Google Earth layers
Rumsey Historical MapsGigapan/Gigapxl PhotosYouTubeBooksNewsWeather
Region: SuperOverlay
"RbNL" of GroundOverlaysExamples:
Google Earth Weatherdisaster imagery
Region: tips and tricks
focus on Lod, especially minLodPixelsminLodPixels most likely > 128
Region with any Feature including ScreenOverlayminLodPixels = 1/2 wid/ht of image tile
256x256 image -> minLodPixels 128512 is 1/4 a typical screen
Time
FeatureTimeStampTimeSpanExample: Google Earth Weather
Time: tips and tricks
TimeStamp for PointsTimeStamp: geographically non-coincidentTimeSpan for OverlaysTimeSpan: geographically coincidentContainers cascadecheckHideChildren
Update
ChangeCreateDeleteExample: Santa
Update: Change
<!-- original fetched with NetworkLink --><kml xmlns="www.opengis.net/kml/2.2"> <Folder> <Placemark id="p1"> <name>Point @ 3,-4.2</name> <description>My movable Point</description> <styleUrl>#some-style</styleUrl> <Point> <extrude>true</extrude> <coordinates>3,4.2</coordinates> </Point> </Placemark> </Folder></kml>
Update: Change
<kml><NetworkLinkControl><Update> <Change> <Placemark targetId="p1"> <name>Point @ 3,-4.2</name> <Point> <coordinates>3,4.2</coordinates> </Point> </Placemark> </Change></Update></NetworkLinkControl></kml>
Update: NetworkLinkControl and cookie
<kml><NetworkLinkControl> <!-- name=value compat with cgi parsing --> <cookie>count=123</cookie> <Update> <Change> <Placemark targetId="p1"> <Point> <coordinates>[coords for 123]</coordinates> </Point> </Placemark> </Change> </Update></NetworkLinkControl></kml>
ExtendedData
FeatureData: untyped dataSchema and SchemaData: typed data"<xs:any>": any XMLballoon templating with shared styleExample: Google Earth Weather(Metadata deprecated)
ExtendedData: Example: Weather
<Placemark> <name>...</name> <styleUrl>http://.../style.kml#sunny</styleUrl> <ExtendedData>...</ExtendedData> <Point>...</Point></Placemark>
ExtendedData: Example: Weather
<!-- style.kml --><Style id="sunny"> <IconStyle> <Icon><href>sunny.jpg</href></Icon> </IconStyle> <LabelStyle>...</LabelStyle> <BalloonStyle> <text> <!-- 50 entities replaced in one template --> ...<td>$[01_Temperature]</td>... </text> </BalloonStyle></Style>
ExtendedData: Example: Weather
<ExtendedData> <Data name="location"> <value>Shillong, IN as of 2008-05-28 17:00</value> </Data> <Data name="00_Temperature"> <value>80°F / 27°C</value> </Data> <Data name="00_Phrase"> <value>Haze</value> </Data></ExtendedData>
ExtendedData: Example: weather
FeatureData: untyped dataSchema and SchemaData: typed data"<xs:any>": any XMLballoon templating with shared styleExample: Google Earth Weather(Metadata deprecated)
ExtendedData: tips and tricks
ExtendedData/Datathe comment trick
Future enhancement
Future enhancement
ExtendedDataXSD extension mechanismOGC SWG
Demo
