gistfile1.pyx

#cython: cdivision=True
#cython: boundscheck=False
#cython: nonecheck=False
#cython: wraparound=False

cimport numpy as cnp
import numpy as np

from libc.math cimport sin, cos, M_PI, round



def _orb_loop(double[:, ::1] image, Py_ssize_t[:, ::1] keypoints,
              double[:] orientations, int[:, ::1] pos0, int[:, ::1] pos1):

    cdef Py_ssize_t i, d, kr, kc, pr0, pr1, pc0, pc1, spr0, spr1, spc0, spc1
    cdef double angle

    cdef char[:, ::1] descriptors = np.zeros((keypoints.shape[0], 256),
                                             dtype=np.int8)

    for i in range(keypoints.shape[0]):
        angle = orientations[i]
        sin_a = sin(angle * M_PI / 180.)
        cos_a = cos(angle * M_PI / 180.)

        kr = keypoints[i, 0]
        kc = keypoints[i, 1]

        for j in range(256):
            pr0 = pos0[j, 0]
            pr1 = pos1[j, 0]
            pc0 = pos0[j, 1]
            pc1 = pos1[j, 1]

            spr0 = <Py_ssize_t>round(cos_a * spr0 + sin_a * spc0)
            spc0 = <Py_ssize_t>round(cos_a * spr0 - sin_a * spc0)
            spr1 = <Py_ssize_t>round(cos_a * spr1 + sin_a * spc1)
            spc1 = <Py_ssize_t>round(cos_a * spr1 - sin_a * spc1)

            if image[kr + pr0, kc + pc0] < image[kr + pr1, kc + pc1]:
                descriptors[i, j] = True

    return np.asarray(descriptors)