| 摘要 |
PURPOSE:To attain the aggregation of rectangular graphic data with small numbers and to improve conversion efficiency, by specifying the allowable value of an error generated with approximating a circular arc with a straight line when the data of circular arc graphic, such as a circle and an annulus ring, are converted to the data of rectangular graphic. CONSTITUTION:When the circular graphic arc data with the coordinate of a center O (x0, y0) and a radius (r), are converted to the rectangular graphic data, first, the circumference of a circle A is equally divided into (n) pieces, division points A1-An are successively linked, and the circle A is made into a polygon B. Next, the facing positions of the division points are successively linked with straight lines D1-B3, which are paralleled to, upper and lower triangles C1 and C4 are generated in the polygon B, and trapezoids C2 and C3 are generated positioning between them. Thereafter, an error E generated between a line to connect, for example, the division points A1 and A2 of the polygon B and the circular arc facing to the line is calculated by the expression E=r{1-cospi/n}, and out of the areas previously divided by the parallel lines in order to minimize them, the area and number of the trapezoids C2 and C3 sandwiched by the triangles C1 and C4 are increased. |
