Table 15 Influence of parameters on SIFT matching performance

Sigman

The change of Sigman value is irrelevant with the matching quantity on the whole. Thus, Sigman can be regarded as an irrelevant correlation parameter in the test improving matching rate of SIFT algorithm.

Thresh

The change of thresh values is negatively correlated with matching quantity of SIFT algorithm. Therefore, thresh parameter is regarded as a negative correlation parameter in the test improving matching rate of SIFT algorithm.

r

The change of the r values is negatively at first and then becomes positively correlated with matching time of SIFT algorithm, presenting a positive correlation trend after the initial value of 10.

NBP

The change of NBP values is negatively correlated with matching quantity; thus, NBP is regarded as a negative correlation parameter of matching performance in improving matching rate of SIFT algorithm.

NBO

The change of NBO values has overall positive correlation with matching quantity. It can be regarded as a positive correlation parameter in setting of NBO parameter values during the test improving matching rate of SIFT algorithm.

Magnif

The change of magnif values is positively at first and then becomes negatively correlated with matching quantity. When setting parameter values of magnif in the test improving matching rate of SIFT algorithm, a better match rate will be obtained at the value of about 0.5.