What was the difficulty in making the camera unit watertight? I'm guessing a simple solution like transparent globe would cause reflection problems but why couldn't each camera be housed in a rubber-tight casing? The lens could be made waterproof by design and everything else would be in a sealed rubber glove. I'm not implying that the guys who mapped the entire world in 3D couldn't figure out how to waterproof cameras. I'm asking what the core engineering problem was in attempting to waterproof these cameras.
First you need the thing to be optically clear. Then you need it to be watertight even with 100 MPH winds blowing on it. And once that's done, you'll find water inside anyway. Condensation can easily form in a closed container which moves at varying speeds through varying temperatures and has water cooling it suddenly sometimes. You may even end up needing a heater inside the thing before you've got it perfect.
