To prevent the shape points from ch

To prevent the shape points from changing after rotation, the main direction must be assigned to all feature points [5]. If you center the feature points in the circular region and take 6 seconds on the feature point scale, the Haar wavelet response is used to compute the feature points in the image. This method is to calculate the gradient of the image, but the integrated image is used, which improves the computational efficiency. To get the main direction values, you need to design a sector shaped sliding window centered on the direction and with an opening angle of π / 3 and a stair size of about 0.2π / rad. Rotate this sliding window to respond to the Haar wavelet of the image inside the window. Convert the values ​​to be cumulative. The default direction is the direction corresponding to the largest Haar response cumulative value.