 Whereas "Star Wars" mostly featured space sequences, "The Empire Strikes Back" featured not only space dogfights but also an ice planet battle opening sequence and elements of cities that floated among the clouds.For the battle scenes on the ice planet Hoth, the initial intent was to use bluescreen to composite the Imperial walkers into still-shots from the original set.Instead, an artist (Michael Pangrazio) was hired to paint landscapes, resulting in the Imperial walkers being shot using stop motion animation in front of the landscape paintings.