工程制图习题答题区域分割算法研究

Research on Region Segmentation Algorithm of Engineering Drawing Exercises Based on Hough Transform

针对工程制图习题册数字化阅卷时不能快速从中分割出学生答题区域的问题,提出了一种基于投影法的答题区域分割算法。首先对习题图像进行灰度转换、图像二值化等预处理操作,然后使用Canny算子得到边缘图像,进行Hough直线变换,筛选出符合条件的直线,计算出倾斜角完成图像的倾斜校正;之后找出边框的矩形轮廓,结合水平垂直投影法得到的投影特征定位出各小题的图形位置,实现对答题区域的分割。实验结果表明,该算法很好地实现了对工程制图习题的答题区域分割,具有效率高,准确率高的特点。

In order to solve the problem that the students’ question area cannot be quickly segmented from the digital marking of engineering drawing exercise book, an algorithm of question area segmentation based on projection method is proposed. Firstly, preprocess the exercise image such as gray conversion and image binarization, then use Canny operator to get the edge image, carry out Hough line transformation, select the line that meets the conditions, calculate the tilt angle, and complete the tilt correction of the image;then find out the rectangular outline of the frame, and locate the graphic position of each sub problem combined with the projection features obtained by the horizontal and vertical projection method, realize the segmentation of the answer area. The experimental results show that the algorithm can segment the answer area of engineering drawing exercises well, and has the characteristics of high efficiency and high accuracy.