As I experienced it, Szeliski's book is better as a reference as it covers lots of material (just see the number of citations at the end). I don't think it's an

As I experienced it, Szeliski's book is better as a reference as it covers lots of material (just see the number of citations at the end). I don't think it's an easy read without reading (some of) the cited papers (or having background knowledge).