Jr., Alfredo FerreiraFonseca, ManuelJorge, JoaquimMarcos, Adérito and Mendonça, Ana and Leitão, Miguel and Costa, António and Jorge, Joaquim2021-10-142021-10-142021978-3-03868-163-2https://doi.org/10.2312/pt.20031439https://diglib.eg.org:443/handle/10.2312/pt20031439Detecting polygons defined by a set of line segments in a plane is an important step in the analysis of vectorial drawings. This paper presents an approach that combines several algorithms to detect basic polygons from a set of arbitrary line segments. The resulting algorithm runs in polynomial time and space, with complexities of O((N + M)4) and O((N + M)2) respectively, where N is the number of line segments and M is the number of intersections between line segments. Our choice of algorithms was made to strike a good compromise between efficiency and ease of implementation. The result is a simple and efficient solution to detect polygons from lines.Polygon DetectionSegment IntersectionMinimum Cycle Basis10.2312/pt.20031439159-162