SIFT算法中奇怪的八度值？

问题描述

我在opencv代码中使用sift算法从图像中获取描述符和关键点。我的代码是

I am using sift algorithm in opencv code to get descriptors and keypoints from images.My code is

    Ptr<IplImage> image;
    vector<KeyPoint> keypoints;
    OutputArray des;

    Feature2D *descriptor_type = new SIFT()
    Mat image_mat(image);
    (*descriptor_type)(image_mat,noArray(),keypoints,des,false);

在这里，我可以在向量中获取图像的关键点< KeyPoint>。之后，我想得到每个KeyPoint的Octave以获取更多细节。但是，当我为一个图像输入每个关键点八度值时，我想确认它们是否正确似乎很奇怪。

Here I can get the keypoints of the image in vector < KeyPoint > .After that,I want to get the Octave of each KeyPoint for more details .But when I cout each keypoint octave value for one image,it seems so strange that I want to confirm whether they are right.

for(int i=0;i<keypoints.size();i++)
{
     cout<< (keypoints[i].octave) <<endl;
}

9765375
9765375
2621951
8323583
13763071
6488575
12845567
721407
3604991
12321279
9568767
7406079
8585727
4653567
7799295
7799295
5112319
10486271
9961983
6226431
1245951

如果我将SIFT算法更改为SURF算法，它会好起来的。

and if I change SIFT algorithm to SURF algorithm,it will be OK and seem right.

0
0
0
0
0
0
1
0
0
0
0
1
1
1
0
1
1
1
0
0
1
0

所以我想问一下在SIFT算法中Octave值的计算是否在opencv中是正确的？

So I want to ask whether the calculation of Octave value in SIFT algorithm is right in opencv?

推荐答案

刚刚遇到。

似乎SIFT关键点的 octave 值需要修补：

It seems like the octave value for SIFT keypoints needs to by "patched":

keyPoint.octave = keyPoint.octave & 0xFF;

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