Not sure how to handle this, I think that if a Date falls off the given interval the show property value should be ````false```` right? At least that's what I think that Google Earth does, should I just add the complement interval with a ````false```` value? 

It's hard to explain but this may cause intersection/union/superposition between different intervals, is that already handled by the ````TimeIntervalCollection```` class?

I believe the default value for show is ````true```` on the Visualizer.