指纹方向场的估计是指纹识别预处理算法中的重要环节，对算法识别效率起到关键作用。本文提出了一种网格插值模型，该模型以指纹奇异点为中心，将指纹平面做网格划分，利用插值算法建立了方向场与指纹奇异点之间的非线性关系。模型中利用了指纹的全局信息来调整网格点的值，使得它与传统的基于局部信息的方向场算法有本质的区别。在FVC2002 和FVC2004 指纹数据库上的实验结果表明，该模型比传统算法具有更高的准确性和鲁棒性，同时对于低质量的指纹图像，仍然能够给出很好的方向场估计。

Orientation field estimation is an essential preprocessing step and it is crucial for the efficiency of the fingerprint recognition algorithm. In this paper, we propose a Grid-Interpolation Model. It partitions the fingerprint plane around singular points with discrete grids, and builds the nonlinear relationship between orientation field and singular points. The orientation of grid points is adjusted by global information of the fingerprint, which is much different from the conventional method. Two experiments are carried out on FVC2002 and FVC2004 databases and the results indicate that the proposed model can reduce noise more efficiently and has more robust performance than the conventional method. Especially as for fingerprints with bad quality, it also can give satisfactory estimation.