Friday, February 25, 2005

Bentley-Ottmann algorithm implented in PDdemo

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

[BO79] J.L.Bentley and T.Ottmann. "Algorithms for reporting and counting geometric intersections. IEEE Transactions on Computers, pages 643-647, 1979.

Tuesday, February 01, 2005

Teaching Human-Computer Interfaces is time consuming!

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.