Modifying Google Earth ground overlay visibility?

Question

Background:

Using Google Earth Pro version 7.3.4.8248 I would like to control the visibility of several ground overlays. That is, the overlays would turn on and off as the viewer zooms in and out. Ideally, visibility levels would be set independently for each overlay.

I initially considered map scale as a way to control each overlay's visibility, similar to scale dependency in flat, 2D maps. However, scale varies across Google Earth's oblique views, rendering it an improper choice.

I then considered the viewing altitude as a way to control visibility, thinking that upper and lower altitude bounds could be used to turn on and off each overlay. However, a review of the KML Ground Overlay reference page came up empty.

Question::

How to turn on and off ground overlays, depending on how far the user has zoomed in or out?

Answer 1

The equivalent of "scale dependent rendering" in Google Earth's 3D world, and therefore in KML is called "regionation". To use it, you define a box (usually similar in size to the KML object it's connected to), and then specify how big that box it can be (in screen pixels) for it to be active... both minimum (when the KML object appears) and maximum (when it disappears again). Lots more in the documentation... just look for "region", "regionation", or "regionate".

https://developers.google.com/kml/documentation/regions

https://developers.google.com/kml/documentation/kmlreference#region