| 摘要 |
A novel method of tracing a drawing and a novel apparatus for implementing this method. The method and the apparatus presented by the invention can correctly and quickly trace an ellipse from a draft plan. Initially, a display unit displays a draft plan which has been read by an image scanner, and then, the apparatus generates vector data corresponding to the draft plan by activating its own drawing function to trace the draft plan shown on the display screen. The apparatus computes length m0 of a long diameter and length m1 of a short diameter of an ellipse E of the draft plan by directly designating a pair of points Pi0 and Pi1 corresponding to both ends of the short diameter of the ellipse E and another pair of points Pj0 and Pj1 corresponding to both ends of the short diameter of the ellipse E. At the same time, the apparatus computes the direction D and the center point P0 of the long diameter corresponding to the center of the ellipse E, and then, based on those data of length m0 and m 1 of the long and short diameters, the direction D, and the center point P0 of the long diameter, the apparatus eventually generates vector data of the ellipse E. Known ratios for ellipses in specific projection drawings, e.g., an isometric projection, are stored in memory means and may be utilized in generating the vector data.
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