I am working withe Cesium 3D at the moment and want to determine what the equivalent map scale the globe is being viewed at.

I am able to get the viewing altitude in Meters that he Camera is at, but according to this discussion, I would need the eye distance from the surface as well, and I do not understand this.

My ultimate aim is to determine a map scale, convert that to an Openlayers 2 Zoom Level so I can sync the two views (approximately)