COMPUTER ASSISTED CARTOGRAPHIC FEATURE EXTRACTION FROM RASTER SCAN DATA

A SET OF COMPUTER PROGRAMS HAS BEEN DESIGNED AND WRITTEN TO EXTRACT LINEAR CARTOGRAPHIC FEATURES FROM DIGITAL RASTER SCAN DATA. THE UNDERLYING PRINCIPLE OF THIS FEATURE EXTRACTION TECHNIQUE IS TO ESTABLISH POINT-TO-POINT RELATIONSHIPS BETWEEN DISCONNECTED DATA POINTS WITHIN A 2-DIMENSIONAL FIELD FORMED BY THE RASTER POINTS GENERATED BY THE SCANNER. THE OBJECTIVE OF THE PROGRAM SET IS TO COLLECT ENOUGH INFORMATION ABOUT THE FEATURES BEING EXTRACTED SO THAT A CONTINUOUS LINEAL ORDERING OF POINTS CAN BE CONSTRUCTED FOR EACH FROM THE POINT AT WHICH IT IS FIRST ENCOUNTERED IN THE SCAN UNTIL IT TERMINATES OR EXTENDS BEYOND THE BOUNDARIES OF THE CHART BEING SCANNED. AS THE BEHAVIOR OF EACH FEATURE IS ESTABLISHED, ALL BUT THE ESSENTIAL DATA POINTS IN THE FEATURE ARE DISCARDED, THUS RESULTING IN SIGNIFICANT REDUCTION OF THE VOLUME OF DATA THAT MUST BE RETAINED. PRELIMINARY TESTS OF THE PROGRAM SET USING CONTOUR LINE DATA ARE PROCEEDING. /ACSM/