Vail trail map overlay on Google Earth

Ground overlays are images that stick right to the surface of the earth.  They're especially cool on terrain with discernable elevation, like ski slopes, since Earth can tilt to show elevation. I placed the Vail trail map on the Vail mountain, tilted the earth and stuck on some webcam references. Looks great if you set your Earth elevation exaggeration to 3. Here's a screenshot:
screenshot of Google Earth centered on Vail, CO

I'm currently working on Aspen/Snowmass and Steamboat, which are a bit harder, since the trail maps for those resorts (as for most of them) are in relief. Check back in a few days for those.

There's a great list of Colorado ski area placemarks (no overlays, just points) on the keyhole bbs posted by "Beaon" here. Using the "tour" feature to hop around the ski areas really highlights how sweet Colorado's got it for skiing.  Hopefully, I can get to overlaying a few more of these.  I bet a nice '14er' tour'd be enlightening, too.

I started out with the idea of placing DEMs (digital elevation maps) from the US Geological Survey in Earth, possibly through polygons.  (Yawn, I know, but it's a tangentially work-related issue.) As I researched on the keyhole bbs, Google's KML doesn't support tessellated polygons, so that idea was out.  The next idea was to convert the DEM to jpg and use a ground overlay to show it.  Sort of pointless, really, since the DEM's all about elevation and Earth has elevation info in it already.  Granted, Earth doesn't always agree with the DEM, for a variety of reasons which were explained in the forums (I'll edit later and add in some more details).  After all that research, I decided to just test out overlays.  Since snowboarding season's coming up, what better project than to overlay ski trail maps on the actual mountains?

Edit, 10/11/2005 - Steamboat added.