交比不变量在机器视觉中的误差分析及应用

研究成像过程中交比不变量的误差问题.介绍了如何利用两个黑条来构造共线4点的交比;分析了图像像素噪声对交比值精度的影响;给出了一个与摄像机外部参数有关的交比误差不等式,得到了交比误差上下限.利用交比不变性设计了一种结构简单的新型人工路标,这种路标对各种视角及变光照条件下的检测具有很高的鲁棒性.真实图像的检测结果表明,这种人工路标易于识别,被检速度快而准.这对单目自主移动机器人基于人工路标的视觉定位与导航具有重要的实际应用价值.

Error Analysis and Application of Cross-Ratio Invariant to Machine Vision

Based on a linear pinhole camera imaging model, the cross-ratio invariant has been applied to pattern recognition on computer vision for a long time as the most fundamental projective invariant. Then, the error of cross-ratio invariant is proposed and studied. Analyzing the influence of image noise on cross-ratio accuracy, the upper limit and lower limit of error are both obtained. According to the cross-ratio invariance, a new well-simplified artificial landmark pattern is designed to provide very high robustness for detecting under all kinds of viewing angles and illuminant conditions. The detection results of real images showed that the new artificial landmark pattern based on cross-ratio invariant is easy to detect fast and accurately. Landmark pattern is of practical importance in application to the self-localization and the navigation of a single-view autonomous mobile robot based on artificial landmark.