一种改进的ORB特征匹配算法

针对现有的ORB特征匹配算法在图像模糊、光照变化、图像压缩、噪声条件下，匹配准确率下降问题，提出了一种改进的ORB特征匹配算法。首先，在提取特征点过程中，对图像进行网格化处理，并引入四叉树结构，使提取的特征点在图像中均匀分布，解决传统的特征提取方法遇到的特征点集中问题。然后，利用暴力匹配进行初步匹配，并采用交叉验证的方式，剔除部分误匹配，改善暴力匹配的结果。最后，利用高斯核对网格运动统计的结果做加权处理，优化统计结果，进一步剔除误匹配，得到准确率更高的匹配集合。实验结果表明:改进后的算法在图像模糊、光照变化、图像压缩和噪声条件下，平均准确率分别提高了3.5%、4.2%、2.2%和6%。 

An improved ORB feature matching algorithm

An improved ORB feature matching algorithm is proposed to solve the problem of decreasing matching accuracy under the conditions of image blur, light change, image compression and noise. First, in the process of extracting feature points, the image is meshed and quad-tree structure is introduced to make the extracted feature points evenly distributed in the image, thus solving the problem of feature points concentration encountered by traditional feature extraction methods. Then, the brute-force matching is used for preliminary matching, and cross validation is adopted to eliminate some mismatches and improve the result of brute-force matching. Finally, Gaussian kernel is used to weight the results of grid-based motion statistics to optimize the statistical results and further eliminate the mismatches to obtain the matching set with higher accuracy. The experimental results show that this algorithm improves the average accuracy by 3.5%, 4.2%, 1.8% and 6% respectively under the conditions of image blur, light change, image compression and noise.