Part 67: conversion between keypoint and point2f in opencv

author ：liaojiacai    

mailbox ： [email protected]

opencv When detecting the middle diagonal point, you need to vector<KeyPoint> And vector<point2f> Switch between

This is in opencv The version comes with related conversion functions

1、KeyPoint turn point2f

 CV_WRAP static void convert(const std::vector<KeyPoint>& keypoints, CV_OUT std::vector<Point2f>& points2f, const std::vector<int>& keypointIndexes=std::vector<int>());

Using examples ：

KeyPoint::convert(keypoints,point2f, 1, 1, 0, -1);

2、point2f turn KeyPoint

CV_WRAP static void convert(const std::vector<Point2f>& points2f, CV_OUT std::vector<KeyPoint>& keypoints, float size=1, float response=1, int octave=0, int class_id=-1);

Using examples ：

KeyPoint::convert(point2f, keypoint, 1, 1, 0, -1);

See from above ： The names of these two conversion functions are the same , So it's overloaded , The input parameters have different sequences and functions

in addition , According to your own needs , Use the conversion function written by yourself to convert KeyPoint To Point

Next, write your own conversion function according to the reference ：

void KeyPointsToPoints(vector<KeyPoint> kpts, vector<Point2f> &pts) { for (int i = 0; i < kpts.size(); i++) { pts.push_back(kpts[i].pt); } }

void PointsToKeyPoints(vector<Point2f>pts,vector<KeyPoint>kpts) { for (size_t i = 0; i < pts.size(); i++) { kpts.push_back(KeyPoint(pts[i], 1.f)); } }

Reference resources ：How can I convert vector<Point2f> to vector<KeyPoint>? - OpenCV Q&A Forum
http://answers.opencv.org/question/24623/how-can-i-convert-vectorpoint2f-to-vectorkeypoint/