《OpenCV3计算机视觉》 ──   Python语言实现（原书第2版）

static Ptr cv::xfeatures2d::SURF::create ( double hessianThreshold = 100, int nOctaves = 4, int nOctaveLayers = 3, bool extended = false, bool upright = false )

参数：

hessianThreshold Threshold for hessian keypoint detector used in SURF.

nOctaves Number of pyramid octaves the keypoint detector will use.

nOctaveLayers Number of octave layers within each octave.

extended Extended descriptor flag (true - use extended 128-element descriptors; false - use 64-element descriptors).

upright Up-right or rotated features flag (true - do not compute orientation of features; false - compute orientation).