Manohar B. Srikanth P. C. Mathias Vijay Natarajan Prakash Naidu Timothy Poston Visibility volumes for interactive path optimization. 635-647 2008 24 The Visual Computer 7-9 http://dx.doi.org/10.1007/s00371-008-0244-x db/journals/vc/vc24.html#SrikanthMNNP08