"AFj's PhD" blog was created in 2004 to report on-line the PhD work of Alfredo Ferreira (Jr). After finishing his PhD in July 2009, the posting was suspended.
However, after several requests, the blog was reactivated in October 2010."AFj's PhD and after" blog will provide information on Alfredo Ferreira's work as a researcher in INESC-ID and his activities as a Assistant Professor at IST/TULisbon.
Our algorithm for polygon detection (see paper "Polygon Detection from a Set of Lines") starts by detecting the line segment intersections. To that end, we use the Bentley-Ottmann sweep line algorithm [BO79]. Today, we have implemented the intersection reporting functionality in the PDlib library. Thus, the PDdemo application evolved to version 0.2, which is available for download here.
Screenshot of PDdemo in debug mode
References: [BO79] J.L.Bentley and T.Ottmann. "Algorithms for reporting and counting geometric intersections. IEEE Transactions on Computers, pages 643-647, 1979.
During last weeks all my time was consumed by the Human-Computer Interfaces course I teach in IST. I have been correcting and discussing student's projects. Additionaly, the preparation, correction and revision of exams had took several days. Thus, my PhD is on stand by, as well as the correction of my MsC dissertation thesis.