This paper describes an output-sensitive scheme to construct the visibility
graph of a simple polygon with m obstacles and n vertices in optimal O(\E\
+ T + m log n) time where \E\ is the size of the visibility graph and T is
the time required to triangulate the simple polygon with obstacles. We use
a partition of the space into regions called corridors which eases the eff
orts of the construction. Our algorithms are simple and the data structures
used are only linked lists.