Horizontal sum of uint16s stored in an XMM register

Hamiltonian representaiton

XpEnforceKeyPointUniformity is modified from the brisk library: EnforceKeyPointUniformity

call this function to allocate memory for the patch of this keypoint, if the patch of keypoint has already allocated, this function will not reallocat

This function will return 1) feat_min_num_thre: The required minimum features based on the grids and the request_feat_num 2) grid_occ_ratio: The grid

make sure 0x00 keeps 0x00 in the next level

The design concept is to trace rays along the diagonal of FOV, say bottom left to top right passing through the pinhole center. Then take the average

\brief Obtain the generic parameters.

Return value between 0 and 255 [NOTE] Does not check whether the x/y is within the border

[NOTE] Instead of matching the cdf(s), we brute-force scale the histograms and match them directly. This matchingHistogram is intended to match two h

[NOTE] We keep this NON-pyramid general interface to support slave_det_mode = OF This function is a wrapper of the pyramid version.

Quaternion multiplication

1. refine_kp_in_larger_img takes the keypoints in the small image (higher pyramid level), and search in a local region in the large image (lower pyram

static inline void ABT(const Transition::DD &A, const BD &B, DB *ABT) { B.m_Pbwr.GetTranspose(ABT->m_Prbw); B.m_Pbav.GetTranspose(ABT->m_Pvba); B.m_Pb

this is confusing, fucntion name AB means C = A * B, but in fact, it's A * BT

static inline void AB(const SymmetricMatrix2x2f &A, const AlignedMatrix2x3f &B1, const AlignedMatrix2x3f &B2, AlignedMatrix2x3f &AB1, AlignedMatrix2x3

TODO(yanghongtian) : update comments here for this function.