The axial line is defined as the longest straight line representing the maximum extension of a point of space. It can be objectively created.
Hillier, B. & Hanson, J. (1984), The Social Logic of Space, Cambridge University Press: Cambridge. pp.17, 91;
Turner, A., Penn, A., & Hillier, B. (2005) An algorithmic definition of the axial map. Environment and Planning B: Planning and Design 32(3):425-444
Vaughan L., Geddes I. (2009), “Urban form and deprivation: a contemporary proxy for Charles Booth’s analysis of poverty” Radical Statistics 99 46-73