I would like to add a date/time that the KML file was last updated to be displayed as an overaly in Google Earth, is there anyway this could be done?
I would be looking at updating text in a KML file and then this being displayed in google earth.
Many Thanks.
One trick is using the Google Chart API to dynamically create images from text and using that as a screen overlay image in Google Earth.
Example:
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
<ScreenOverlay>
<Icon>
<href><![CDATA[http://chart.apis.google.com/chart?chst=d_text_outline&chld=FFBBBB|16|h|BB0000|b|Hello%20Word]]></href>
</Icon>
<overlayXY x="0.8" xunits="fraction" y="0.8" yunits="fraction"/>
<screenXY x="0.8" xunits="fraction" y="0.8" yunits="fraction"/>
</ScreenOverlay>
</kml>
A screen overlay with embedded images is used in the Paleoglobe KML:
http://www.geology.sdsu.edu/kmlgeology/kmz/paleoglobe/paleogeography.kmz
There are many websites that create images out of text for labels which you embed in a KMZ file and refer to from you KML.
Also, if you want text to appear as a label on the ground at a fixed location then you can use same trick with a GroundOverlay or simply create a Placemark with a name (which is shown on map at that location) and a Style suppressing the icon.