Integrated text and line-art extraction from a topographic map

Our proposed approach to text and line-art extraction requires accurately locating a text-string box and identifying external line vectors incident on the box. The results of extrapolating these vectors inside the box are passed to an experimental single-font optical character reader (OCR) program, specifically trained for the font used for street labels. In the first evaluation experiment, automated techniques are used to identify the boxes and the line vectors. In the second, more comprehensive, experiment an operator marks these using a graphical user interface. OCR results on 544 instances of overlapped street-name boxes show the following improvements due to the integrated processing: the error rate is reduced from 4.1% to 2.0% for characters and from 11.8% to 6.4% for words.