In this paper, they extract elliptical patches while in many papers rectangular patches seem to be more the norm. Intuitively it seems like elliptical patches may yield slightly better performance (corners of rectangles seem likely to be noisy while circular patches catch the content best) while rectangular patches may yield slightly better efficiency (in terms of indexing). What factors should one consider in general when making this decision?

Also a comment along the lines of Paul's. It seems as though they looked at a wide variety of methods in their search for the best approach (23 different settings reported in Table 1) covering a wide range of performance (70.1 to 90.6). It seems like a deeper coverage of *why* certain settings yielded the best performance would be helpful, particularly where some decisions seem quite fundamental.