使用OpenCV获取指定点的SIFT描述符 [英] Get the SIFT descriptor for specified point using OpenCV

问题描述

我想要获得指定点的SIFT功能。这些点是由手而不是由键盘检测器。我的问题是：我只知道点的位置，但不知道尺寸和角度值。如何设置此值？

以下是我的代码：

  int main（）
 {
 Mat img_object = imread（img / test.jpg，0）; 
 
 SiftDescriptorExtractor extractor; 
 Mat描述符; 
 std :: vector< KeyPoint>关键点; 
 
 //设置keypoint位置和大小：对于32x32补丁，我应该将
 // size参数设置为32吗？ 
 KeyPoint kp（50，60，32）; 
 keypoints.push_back（kp）; 
 
 extractor.compute（img_object，keypoints，descriptors）; 
 
 return 0; 
} 
  

对于32x32补丁，我应该将KeyPoint的大小参数设置为32。

解决方案

通常，关键点检测器在一个点周围的局部邻域上工作。这是OpenCV的 KeyPoint 类的 size 字段。 angle 字段是关键点的主导方向（可以设置为-1，注意）。

OpenCV KeyPoint类

这里另一个引用

I want get the SIFT feature for specified points. These points is gotten by hand not by KeyPoint Detector. My question is: I only know the position of the points but have no idea about the size and angle value. How should I set this value?

Here is my code:

int main()
{
    Mat img_object = imread("img/test.jpg", 0);

    SiftDescriptorExtractor extractor;
    Mat descriptors;
    std::vector<KeyPoint> keypoints;

    // set keypoint position and size: should I set 
    // size parameter to 32 for 32x32 patch?
    KeyPoint kp(50, 60, 32);
    keypoints.push_back(kp);

    extractor.compute( img_object, keypoints, descriptors );

    return 0;
}

Should I set the size param of KeyPoint to 32 for 32x32 patch. Is this implementation reasonable?

解决方案

Usually, keypoint detectors work on a local neighbourhood around a point. This is the size field of OpenCV's KeyPoint class. The angle field is the dominant orientation of the keypoint (this could be set to -1, note).

OpenCV KeyPoint class

Another reference here.

这篇关于使用OpenCV获取指定点的SIFT描述符的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！