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Procedure for Rectifying a Roughly Sketched Drawing

IP.com Disclosure Number: IPCOM000084717D
Original Publication Date: 1975-Dec-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 4 page(s) / 45K

Publishing Venue

IBM

Related People

Fitzgerald, WJ: AUTHOR [+2]

Abstract

This is a computer-aided procedure which enables a roughly sketched drawing to be rectified in such manner that all drawing lines are placed as nearly as possible in their intended orientations and directions, and the shape of the roughly sketched object is preserved with a reasonably high degree of fidelity.

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Procedure for Rectifying a Roughly Sketched Drawing

This is a computer-aided procedure which enables a roughly sketched drawing to be rectified in such manner that all drawing lines are placed as nearly as possible in their intended orientations and directions, and the shape of the roughly sketched object is preserved with a reasonably high degree of fidelity.

In the use of computer-aided drafting systems for converting rough sketches into finished drawings, there will be occasions when the operator would like to see how an object which he has sketched in rough form would appear if the drawing lines were made true, without grossly altering the original shape of the sketched object.

Referring, for example, to the roughly sketched object shown by solid lines in Fig. 1, let it be assumed that each line in this sketch except the line fg is intended to be an axial line (i.e., parallel with either the horizontal or vertical axis of the figure) and that the line fg is oriented approximately as intended. In accordance with the procedure described herein, the original roughly sketched object a-b-c-d- e-f-g-h-i is rectified into the object a'-b'-c'-d'-e'-f'-g'-h'-i' wherein all lines except f'g' are axial.

It will be noted that the original sense of direction is not lost in any of the rectified drawing lines, even under conditions which commonly cause a loss of direction in other rectifying schemes. As an example, although point d in the original sketch is above point c in that sketch but below point c' in the rectified sketch, point d' nevertheless is positioned above point c' in the rectified sketch, thereby preserving the upper-lower relationship that points d and c had in the rough sketch. If point d of the original figure had merely been shifted to the left following rectification of the line bc, the line c'd' then would have run in the downward direction, losing the upward sense of direction of the original line cd.

With regard to shape fidelity, it will be noted that the original orientation of the nonaxial line fg is not very different from that of the line f'g' after rectification. 0n the other hand, the length of the rectified vertical line e'f' greatly exceeds that of the original sketch line ef. Where a choice of this kind must be made, the present rectification scheme favors minimizing the changes that are made in the coordinates of nonaxial line ends, notwithstanding the effects this may have upon the lengths of adjoining axial lines. The reason for doing this is that nonaxial lines in general are more likely to characterize the shape of an object bounded by both axial and nonaxial lines; hence it is advantageous to minimize changes in the orientations of nonaxial lines.

In carrying out this rectification procedure, the operator uses a graphic input device such as an electronic tablet and touches his stylus successively to the line end points a, b, c, etc. of a roughly sketched object such as the one shown by solid lines in Fi...