How the problems in converting the paper map into vector map was overcome?
The map capture process can be done in the following ways: • Use the ladder table data on the GIS system to convert into a vector map. • Use the hard copy map as the background material to plot the map online. • Heads up digitisation – this processes uses the raster image of the existing map. The raster image which appears on the screen is used as a background to plot the map using the GIS software. After detailed study in collaboration with the officials of Simens Information Services Limited Chennai it was decided to adopt “heads up” digitisation method. The reasons were many. For example, the ladder table to GIS conversion process failed because the ladder tables did not provide all the details. As a result, only a part of the map could be built using the ladder. Moreover, the data capture system would be put to serious risk as there were multiple flaws in the ladder data itself. The scope for a second verification became a casualty. Using the plotter on the existing map had already
