Toward an algorithm of visual design. The mathematical approach of Hermann Maertens' optische-massstab

In the second half of the 19th century, art history, aesthetic reflection, and psychology of perception often crossed issues and methods, implicitly seeking for a mutual legitimacy and orienting their development. The work of the German architect Hermann Eduard Maertens (1823-1898), and in particular his research on the Optische-Maassstab in 1870s and 1880s, lies in a common area with the various scientific and artistic disciplines that were evolving rapidly in those years. This enquiry focuses on his use of geometry and mathematics to arrange a tool for an innovative visual deterministic process in architecture and urban design as well a key to an original critical approach to historical cities and their spaces.