A raster-mode algorithm for interactive modification of line drawing data

Geographic data files are characteristically very large, given the high degree of precision needed for most cartographic production and analysis applications. As the ease of capturing large volumes of high-precision spatial data and the subsequent reliance on automated methods for handling such data increase, there is an increasing need for efficiency in terms of both storage space and speed. More and more graphic data are now being captured in raster instead of vector format. This means that raster methods for processing raster-formatted data need to be investigated as a means of increasing efficiency by avoiding the raster-vector-raster conversion process. Raster algorithms to perform a wide range of tasks already exist. One exception, however, is raster-mode update. This paper presents an algorithm for the modification of cartographic or any similar type of raster-formatted line drawing data which operates on rasters exclusively.