| 摘要 |
<p>PURPOSE:To reduce the number of point data and to enhance the accuracy of a shape which can be reproduced with the remaining point data by determining that the point data can not be thinned out if a variation in the shape before and after a determining point exceeds a predetermined value, but by determining that the point data cannot be thinned out if it is not. CONSTITUTION:If point data D5 are determining point data, point data 2, 3, 4, 5 fall in a front point data group, and point data 5, 6, 7, 8 fall in a rear point data group. At first, a phantom curve corresponding to a shape given by the front point data group is obtained by a quadratic approximate expression, and a tangential line P to the phantom line, passing through the point data 5 is obtained in the form of a unit vector. Similarly, a tangential line Q of the unit vector formed is obtained from the rear point data group. A distance M between the front ends of both tangential lines P, Q is calculated. The opening angle of the lines P, Q and a variation in the shape is reversely proportional to each other, that is, the smaller the angle, the larger the variation in the shape. Accordingly, a distance M0 of the opening angle of the tangential lines P, Q having a variation in the shape, which exceeds a predetermined value, is obtained. If the calculated distance M is below a predetermined value, the point data cannot be thinned out since a variation in the shape exceeds a predetermined value, and are stored in a memory part. However, if it is not, the point data can be thinned out.</p> |
