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# Tracking Pattern Line Following/Vectorization Technique

IP.com Disclosure Number: IPCOM000079200D
Original Publication Date: 1973-May-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 43K

IBM

## Related People

Gurwitz, D: AUTHOR [+3]

## Abstract

The tracking pattern line following/vectorization technique, transforms run-length coded digital raster data of a line drawing into a vector list. The procedure used for line following, once the starting point of a line has been established, is to measure the percent overlap of a tracking pattern with scan data for a number of possible next points, and choose the next point on the basis of maximum percent overlap. This is illustrated in Fig. 1(a). Point 1 is the initial point and points 2, 3, and 4 are the next possible points. Point 3 is chosen as the next point, because the percent overlap of the tracking pattern for this position is greater than the percent overlap for any of the other positions.

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Tracking Pattern Line Following/Vectorization Technique

The tracking pattern line following/vectorization technique, transforms run- length coded digital raster data of a line drawing into a vector list. The procedure used for line following, once the starting point of a line has been established, is to measure the percent overlap of a tracking pattern with scan data for a number of possible next points, and choose the next point on the basis of maximum percent overlap. This is illustrated in Fig. 1(a). Point 1 is the initial point and points 2, 3, and 4 are the next possible points. Point 3 is chosen as the next point, because the percent overlap of the tracking pattern for this position is greater than the percent overlap for any of the other positions.

There are two procedures used for the determination of starting points. The first set of starting points is determined by searching the run-length coded input data for runs that are either overlapped or underlapped but not both, and which are greater than a prespecified length. The case of an underlapped run is shown in Fig. 1(b). The X-coordinate of the starting point is at the center of the initially encountered run. The Y-coordinate is that of the run midway between the initially encountered run and the last adjacent run, which intersects a line going through the X-coordinate and perpendicular to run direction. Line following is initiated to the right and left of this start point.

The second set of starting points is determined by searching the run-length coded raster data for runs which are either underlapped or overlapped but not both, and which are less than a prespecified lengt...