I was curious about how important it was that they had a particular known pattern to work with. It sounds like they could do the same technique with any reflected image, as long as it had a line and a point in a known world position - so if there was a well-matched model of the scene, that should do just as well as a calibrated reference pattern, right?

I suspect that this is true, but that it just wasn't the focus of the paper to extend it in that way, but I'd be interested to hear if anyone thinks it's due to a limitation in the technique.