The "Polygon Detector" prototype takes as input an SVG file containing a set of lines and produces another SVG file with the corresponding polygon set. Note that the polygon detection algorithm runs in O(n^4), where "n" is the number of lines obtained after intersection removal. Thus, for a complex line set, it may take a while to detect the polygons. For instance, processing the line set depicted below took around twelve minutes in a Intel Pentium M 2GHz 1MB RAM computer running Windows XP.
If interested, you can download the current stable version of the prototype [ZIP 434KB] or the paper where the algorithm was initially paper, "Polygon Detection from a Set of Lines", Ferreira, A., Fonseca, M.J. and Jorge, J.A., Actas do 12º Encontro Português de Computação Gráfica (12th EPCG), pages 159-162, Porto, Portugal, Oct 2003 [PDF 86KB].