Method of encoding lines
View Patent ↗In a method of encoding lines in a print from the skin and particularly a fingerprint, one line at a time is encoded by means of vertices, which include the starting point and the end point, that are situated on the line, in which case segments of connecting line between adjacent vertices are no more than a preset distance away from the line.
1. A method of encoding lines in a print from the skin, and particularly a fingerprint, characterized in that one line at a time is encoded by means of vertices, which include the starting point and the end point, that are situated on the line, such that connecting line segments between adjacent vertices are no more than a given distance away from the line, characterized in that the distance between one point at a time and a connecting line segment is calculated as the distance to the start or end of the connecting line segment if the perpendicular from the given point to the straight line containing the connecting line segment is not situated on the connecting line segment.
2. A method as claimed in claim 1 , characterized in that, after the starting point and the end point have been determined, a search is made for that point on the line that is the maximum distance away from a connecting line between the starting point and the end point, the point that is the maximum distance away is stored as a first vertex, a search is made, between the first vertex and the starting point and the end point, for other points that are the maximum distance away from their associated connecting line segment, the points that are found constitute a second and a third vertex, between which and the starting point, the end point, and the first vertex a search is made for further points each at the maximum distance, which further points form further vertices, and a search of this kind is continued until such time as no point is found that is at a distance greater than said given distance.
3. A method as claimed in claim 1 , characterized in that said given distance is less than a third of the distance between the lines.
4. A method as claimed in claim 1 , characterized in that branching lines are split apart at the branching.
5. A method as claimed in claim 1 , characterized in that closed lines are broken open.
6. A method as claimed in claim 1 , characterized in that, in determining a distance from a connecting line segment, the perpendicular from the given point to the straight line containing the connecting line segment is calculated.