Viraph: exploring the potentials of visibility graphs and their analysis

Background Visibility Graph Analysis (VGA) is a space syntax method for quantifying some socio-spatial properties of the built environment by mapping the floor plan into a grid. Presently, VGA mainly relies on mean values of the measures while the individual room-to-room (“interspatial”) relations are not considered or achievable by the common VGA software – depthMapX. Methods A new software package, Viraph, is developed using a weighed Dijkstra algorithm to calculate depths. The floor plan is mapped into convex areas to increase the speed of calculation. The interspatial relations are calculated by averaging the point-to-point depths in-between. Results The effectiveness of Viraph is demonstrated through a case study, which compares the houses from the late Victorian era with Wright’s Prairie style with a detailed analysis of Francis Little House (designed in 1902). In summary, Viraph has showed a significantly higher calculation speed for VGA, and capability of capturing some socio-spatial relations of the styles by measuring the interspatial depth. Conclusions Viraph’s improved speed for measurement has made VGA analysis more accessible for general design researchers and practitioners. Further this paper shows that the added feature of measuring the interspatial depth opens a new perspective for enhancing traditional space syntax analysis.