Google Earth Property Debug Tool
KML supports a feature called a NetworkLink that can chain static KML files together or dynamically generated KML via a
"servlet" at the end of a URL.
An example KML file with Networklink shows all the available properties from the Google Earth client as described below.
To see it for yourself, you can download this KML file
Screenshot of DebugTool generated balloon description
A related KML file
uses the BBOX
from which to generate a placemark at the center of the view. Useful tool if you need the exact center latitude/longitude
of the current view in Google Earth.
The power of the NetworkLink in KML is the ability to receive the client properties from Google Earth which include characteristics of the
map view and the Google Earth client itself. Using these properties a backend service could tailor the information to the current view and/or
settings of the map. This can greatly reduce data that won't be useful in the target context. Having 3-D terrain enabled could generate a
different set of content then if it's disabled as is knowledge of the map screen resolution. No personal information other than these properties
can be passed from Google Earth to a backend service through this mechanism.
Also available are basic client properties:
- BBOX=[bboxWest],[bboxSouth],[bboxEast],[bboxNorth] - This information matches the Web Map Service (WMS) bounding box
specification. This defines the north, east, west, and south-most coordinates of the current view but note that the bounding box
is larger than what is actually displayed.
- [lookatLon], [lookatLat] - longitude and latitude of the point that <LookAt> is viewing
- [lookatRange], [lookatTilt], [lookatHeading] - values used by the <LookAt> element (see descriptions of <range>, <tilt>, and <heading> in <LookAt>)
- [lookatTerrainLon], [lookatTerrainLat], [lookatTerrainAlt] - point on the terrain in degrees/meters that <LookAt> is viewing
- [cameraLon], [cameraLat], [cameraAlt] - degrees/meters of the eyepoint for the camera
- [horizFov], [vertFov] - horizontal, vertical field of view for the camera
- [horizPixels], [vertPixels] - size in pixels of the 3D viewer
- [terrainEnabled] - indicates whether the 3D viewer is showing terrain
- [clientVersion] - version of the Google Earth client (e.g. 188.8.131.5213)
- [kmlVersion] - KML version supported (usually 2.2)
- [clientName] - name of client (normally Google Earth)
- [language] - default language of client (e.g. 'en' for English)
Under the covers, Google Earth rewrites the URL it connects to and appends the values of the httpQuery and viewFormat parameters after
performing an entity substition. So for example, if the NetworkLink element is defined as such:
Then the URL called by Google Earth would be something like the following through an HTTP GET request:
Google Earth (TM) and Google Maps (TM) are registered trademarks of Google Inc. KML4Earth is not affiliated with Google.
Created and maintained by jasonm1