The all line axial map is a set of lines made up of all lines drawn tangentially to vertices (e.g. building faces) that are intervisible.
All line analysis
Hillier, B. (1996, 2007), Space is the Machine: A Configurational Theory of Architecture. Space Syntax: London, UK.pp.271
Penn, A., Conroy, R., Dalton, N., Dekker, L., Mottram, C.,Turner, A. (1997), Intelligent architecture: new tools for the three dimensional analysis of space and built form, in Proceedings of the 1st International Symposium on Space Syntax University College London, London, pp. 30.3-4
Turner, A., Penn, A., & Hillier, B. (2005),An algorithmic definition of the axial map. Environment and Planning B: Planning and Design 32(3):425