Syntax analysis in automated digitizing of maps

Abstract

To enter analog maps into well-structured cartographic databases several consequtive steps of data processing have to be performed. The processing starts with scanning, binarization and vectorization. Thereafter, segmentation and recognition of the unintelligent vectors must be done before the building of the database can be started. The recognition step usually involves many separate recognition tasks such as recognition of isolated iconic symbols, of iconic symbol orientation, straight lines and height contour lines. Often, a large part of these tasks still have to be solved by manual labelling of the vector structures interactively.

In this paper we report on a special syntactic approach to automate some recognition tasks that frequently arise in the digitizing of maps. We have used this method, called syntax directed translation schemata, to automate the recognition of numbers with one decimal, correct some single symbol classification errors and to find legal descriptions of parcel codes on cadastral maps.

We conclude that syntax directed translation schemata are good tools to reduce substantially the interactive work load in the recognition step of map digitizing.