Entropy in DepthMap is a measure of the distribution of locations of spaces in terms of their depth from a space rather than the depth itself. If many locations are close to a space, the depth from that space is asymmetric, and the entropy is low. If the depth is more evenly distributed, the entropy is higher. This measure is able to express culturally significant topological differences among spatial layouts. For the mathematical definition, see Hillier, B. et al (1987) pp. 365; Turner, A. (2001) pp.8.
Hillier, B., Hanson, J., and Graham, H. (1987), Ideas are in things: an application of the space syntax method to discovering house genotypes, Environment and Planning B: Vol 14, 363-385. pp. 364-365;
Turner, A. (2004), DepthMap4: A Researcher’s Handbook, UCL. pp. 15;
Turner, A. (2001) Angular Analysis. In Proceedings of the 3rd International Symposium of Space Syntax, 1-13.pp.8