1. A method of determining spatio-temporal correspondence between different sets of video data, the method comprising: inputting the sets of video data; representing the video data as ordered sequences of visual nucleotides; determining temporally corresponding subsets of video data by aligning the sequences of visual nucleotides; computing a spatial correspondence between the temporally corresponding subsets of video data (spatio-temporal correspondence); and outputting the spatio-temporal correspondence between subsets of the video data.