脊点集稳健裁剪和惩罚约束的高精度靶标点提取

Marking point extraction with high accuracy based on ridge points refining and punishment restriction

高精度快速靶标点的自动提取是相机标定、立体解算、视觉导航等关键领域的基础。定位精度和算法稳健性为难点之所在,采用重心约束法检测初始交点后,通过对称性约束探测直线附近的"脊点"点集,然后采用最小二乘线性拟合初值并迭代滤掉粗差,再采用改进的Hough变换进一步求得交点的位置。然后采用惩罚函数在初始点附近步进调整,精确确定靶标点的位置信息和方向。算法能够更强地适应噪声环境下、光照变化、图像旋转等影响,达到小于0.05像素的定位精度。

Automatic marking points extracting with high accuracy is basic for calibration, stereo calculation, visual navigation and other applications. The bottle-neck is the accuracy and robustness. Based on the rough point from the cross of lines of the neighbor barycenters in two directions, the ridge points were detected by the symmetric function and refined by an iterative least square method, based on the refined ridge points, the Hough transform was improved for determining the lines and their intersections. At last, the position of the marking points was to be adjusted by the penalty function with a changing step along the descent direction both in deflection and rotation separately. Our algorithm is robust to noisy, rotation, illumination variations and a certain degree of distortions, the accuracy could be less than 5 percents of a pixel.