B-SHOT特征描述子的源码
时间: 2024-06-08 15:05:25 浏览: 9
B-SHOT是一种局部特征描述符,它基于SIFT算法,并且具有更高的计算速度和更小的维度。下面是B-SHOT特征描述子的示例代码:
```python
import cv2
import numpy as np
def bshot(image, keypoints):
# 将图像转换为灰度图像
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
# 创建SIFT对象
sift = cv2.xfeatures2d.SIFT_create()
# 检测关键点和描述符
kp, des = sift.compute(gray, keypoints)
# B-SHOT参数
patch_size = 31
n_bits = 256
# 计算B-SHOT描述子
bshot_descriptors = []
for i in range(len(kp)):
# 提取关键点的位置和方向
x, y = kp[i].pt
angle = kp[i].angle
# 计算局部patch的梯度
patch = gray[int(y-patch_size/2):int(y+patch_size/2),
int(x-patch_size/2):int(x+patch_size/2)]
dx = cv2.Sobel(patch, cv2.CV_32F, 1, 0)
dy = cv2.Sobel(patch, cv2.CV_32F, 0, 1)
magnitude, angle = cv2.cartToPolar(dx, dy, angleInDegrees=True)
# 将patch分成四个子区域并计算每个子区域的B-SHOT描述子
subpatch_size = int(patch_size / 2)
for j in range(4):
subpatch = patch[int(j/2)*subpatch_size:int((j/2+1)*subpatch_size),
int(j%2)*subpatch_size:int((j%2+1)*subpatch_size)]
sub_magnitude = magnitude[int(j/2)*subpatch_size:int((j/2+1)*subpatch_size),
int(j%2)*subpatch_size:int((j%2+1)*subpatch_size)]
sub_angle = angle[int(j/2)*subpatch_size:int((j/2+1)*subpatch_size),
int(j%2)*subpatch_size:int((j%2+1)*subpatch_size)]
bshot_subdescriptor = np.zeros(n_bits)
for k in range(subpatch.shape[0]):
for l in range(subpatch.shape[1]):
bin_index = int(sub_angle[k,l] / 360.0 * n_bits)
bshot_subdescriptor[bin_index] += sub_magnitude[k,l]
bshot_subdescriptor = cv2.normalize(
bshot_subdescriptor.reshape(1,-1), None, norm_type=cv2.NORM_L2).flatten()
bshot_descriptors.append(bshot_subdescriptor)
return np.array(bshot_descriptors)
```
该代码使用OpenCV库实现。它首先使用SIFT算法检测关键点和描述符。然后,对于每个关键点,它将其周围的局部区域分成四个子区域,并计算每个子区域的B-SHOT描述符。最终,它将所有的描述符组合成一个数组并返回。
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