Abstract: SURF algorithm has been extensively applied in object recognition and computer vision for its speed and well-performed robustness.To keep rotation invariance in original algorithm,Bay got dominant orientation of keypoint to which gradients were computed relatively,and this part takes considerable time.In this essay,a couple of isotropic vectors are selected to reconstruct feature descriptor to keep rotation invariance as well as computing speed by using Integral Image thereby exempting algorithm from consuming time for above operations.The test has proved that the performance of proposed method is improved almost 30% allowing for error to a certain extent.

Key words: SURF algorithm;isotropy;feature descriptor;rotation invariance