Abstract: Engineering design revolved a lot of design data. Partial design data were described in the form of curve chart. Spiral angle coefficient curve was a typical engineering curve and had the characteristics of engineering curves. In the paper, spiral angle coefficient curve was as an example in which scanning image preprocessing, image revision, image cropping, binarization processing, mesh removing, characteristics point extracting of spiral angle coefficient curve were put forward. Furthermore, the least square method was used to fit characteristic points and accomplish digitizing of engineering curves.

Key words: Engineering curves, Image revision, Characteristics point detection, Curve fitting;Least square method

摘要： 工程设计中涉及大量的设计资料,设计资料的一部分是以曲线图表的形式存在,螺旋角系数曲线是
典型的工程曲线,具备工程曲线的特征。以螺旋角系数曲线图像为例,提出扫描图像的预处理、图像校正、图像裁
剪、二值化处理、网格去除、特征点提取等方法,进一步利用最小二乘法对特征点进行曲线拟合,实现工程曲线的数
字化。

关键词: 工程曲线 , 图像校正 , 特征点提取 , 曲线拟合, 最小二乘法