PT Unknown AU Josep Llados Enric Marti Jaime Lopez-Krahe TI A Hough-based method for hatched pattern detection in maps and diagrams BT Proceeding of the Fifth Int. Conf. Document Analysis and Recognition ICDAR ’99 PY 1999 BP 479 EP 482 DI 10.1109/ICDAR.1999.791829 AB A hatched area is characterized by a set of parallel straight lines placed at regular intervals. In this paper, a Hough-based schema is introduced to recognize hatched areas in technical documents from attributed graph structures representing the document once it has been vectorized. Defining a Hough-based transform from a graph instead of the raster image allows to drastically reduce the processing time and, second, to obtain more reliable results because straight lines have already been detected in the vectorization step. A second advantage of the proposed method is that no assumptions must be made a priori about the slope and frequency of hatching patterns, but they are computed in run time for each hatched area. ER