How to Extend Visibility Polygons by Mirrors to Cover Invisible Segments
نویسندگان
چکیده
Given a simple polygon P with n vertices, the visibility polygon (VP) of a point q (VP(q)), or a segment pq (VP(pq)) inside P can be computed in linear time. We propose a linear time algorithm to extend VP of a viewer (point or segment), by converting some edges of P into mirrors, such that a given non-visible segment uw can also be seen from the viewer. Various definitions for the visibility of a segment, such as weak, strong, or complete visibility are considered. Our algorithm finds every edge such that, when converted to a mirror, makes uw visible to our viewer. We find out exactly which interval of uw becomes visible, by every edge middling as mirror, all in linear time.
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