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Copyright © 2007, 2008 Open Geospatial Consortium, Inc. All Rights Reserved.
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14 Views
14.1 kml:AbstractViewGroup
14.1.1 Structure
kml:AbstractViewGroup id=ID [0..1]
targetId=NCName [0..1] kml:AbstractObjectGroupSimpleExtensionGroup ...
kml:AbstractObjectGroupSimpleExtensionGroup [0..] kml:AbstractViewSimpleExtensionGroup ...
kml:AbstractViewSimpleExtensionGroup [0..] kml:AbstractViewObjectExtensionGroup ...
kml:AbstractViewObjectExtensionGroup [0..] kml:AbstractViewGroup
14.1.2 Description
Abstract: yes This element can be used wherever the following element is referenced:
• kml:AbstractObjectGroup
The following elements can be used wherever this element is referenced:
• kml:LookAt • kml:Camera
An earth browser displays KML graphics overlaid on a backdrop image which is typically that of the earth. In addition to describing the overlaid graphic elements, KML can define a
geographic view of the overlaid graphics and the backdrop image.
14.1.3 Content
14.1.3.1 kml:AbstractViewSimpleExtensionGroup
See 6.6.3.1 Simple Element Substitution.
14.1.3.2 kml:AbstractViewObjectExtensionGroup
See 6.6.3.2 Complex Element Substitution.
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14.2 kml:Camera
14.2.1 Structure
kml:Camera id=ID [0..1]
targetId=NCName [0..1] kml:ObjectSimpleExtensionGroup ... kml:ObjectSimpleExtensionGroup [0..]
kml:AbstractViewSimpleExtensionGroup ... kml:AbstractViewSimpleExtensionGroup [0..]
kml:AbstractViewObjectExtensionGroup ... kml:AbstractViewObjectExtensionGroup [0..]
kml:longitude ... kml:longitude [0..1] kml:latitude ... kml:latitude [0..1]
kml:altitude ... kml:altitude [0..1] kml:heading ... kml:heading [0..1]
kml:tilt ... kml:tilt [0..1] kml:roll ... kml:roll [0..1]
kml:altitudeModeGroup ... kml:altitudeModeGroup [0..1] kml:CameraSimpleExtensionGroup ... kml:CameraSimpleExtensionGroup [0..]
kml:CameraObjectExtensionGroup ... kml:CameraObjectExtensionGroup [0..] kml:Camera
14.2.2 Description
This element can be used wherever the following element is referenced:
• kml:AbstractViewGroup
The
kml:Camera
element specifies the position and orientation of a virtual camera. This can be used to specify views of the earth or of objects in space.
A
kml:Camera
element should contain the
kml:longitude
,
kml:latitude,
and
kml:altitude
child elements outside of an update context, that is when not a descendant of
kml:Update
. 14.2.3
Defining a View
The
kml:Camera
element specifies the position of the view point of the camera using the child elements
kml:longitude
,
kml:latitude
,
kml:altitude
and
kml:altitudeMode
. The orientation of the camera is specified using the additional child elements
kml:heading
,
kml:tilt
and
kml:roll
. The initial or zero position of the camera is defined by an earth-fixed frame lying in a
meridian plane plane containing the view point, the poles, and the earths center of mass, with the Z-axis normal to the earths surface, the Y-axis directed away from the equator, and
the X-axis such as to form a right handed orthogonal frame.
A body-fixed reference frame is assumed attached to the virtual camera, with the Z-axis along the optical axis of the camera, the Y-axis through the top of the camera, and the X-axis
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Copyright © 2007, 2008 Open Geospatial Consortium, Inc. All Rights Reserved.
173 such as to form a right handed orthogonal frame. In the zero position of the camera, the
camera body Z-axis is aligned with the –Z axis and the body Y axis with the Y axis. The orientation of the camera is then defined by the following sequence of rotations Euler
angles which must be performed in the stated order:
•
kml:altitude
– translate along the Z axis to the specified altitude. •
kml:heading
– clockwise rotation around the Z axis. The range of the heading is from 0 to 360 degrees.
•
kml:tilt
– counter clockwise rotation around the X axis. The range of the tilt is from -180 to + 180 degrees.
•
kml:roll
– clockwise around the Z axis again. The range of the roll is from -180 to +180 degrees
The camera body axes are shown as follows:
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The earth-fixed frame specifying the initial zero orientation of the camera is illustrated below:
14.2.4 Order of Rotation
