Super-overlays are a form of KML in which data is broken up into regions. This allows Google Earth to refresh/request only particular regions of the map when the view area changes. Super-overlays are used to efficiently publish large sets of data. Please see Google’s page on super-overlays for more information.
GeoServer supports two types of super-overlays: raster and vector. With raster super-overlays, GeoServer intelligently produces imagery appropriate to the current zoom level and dynamically outputs new imagery when the zoom level changes. With vector super-overlays, feature data is requested for only the visible features and new features are dynamically loaded as necessary. Raster super-overlays require fewer resources on the client, but vector super-overlays have a higher output quality.
When using the KML Reflector, super-overlays are enabled by default, whether the data in question is raster or vector. For more information on the various options for KML super-overlay output, please see the page on the KML Reflector.
It is possible to easily create overlays for Google Earth with MapTiler Desktop.
Open the application and choose your file(s).
If the image is a GeoTIFF, it already has a position inside, otherwise, you have to specify Coordinate system and Georeference. Once the satisfying setting is done, proceed to the "Format of output" page by clicking the export button.
Here select Google Earth KML as the output format.
Then, click on continue, render, create a new folder and start rendering. Once the rendering process is finished, the .kml file is ready for you in the rendering folder. You can either view the content of the folder by clicking on the Open folder option or open Google Earth directly by clicking on Preview the map option.
Once the file is opened by Google Earth application the map is positioned on the place where it should be and perfectly overlays the terrain, it is possible to pan, zoom and view it from all sides in 3D.
You can try to create a KML super overlay with the sample image of the Grand Canyon.