# week3_code

**Repository Path**: sika0819/week3_code

## Basic Information

- **Project Name**: week3_code
- **Description**: 第三周代码
- **Primary Language**: Unknown
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2019-04-24
- **Last Updated**: 2020-12-19

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# 背景提取
## 源码
```c++
#include "pch.h"
#include <iostream>
#include "opencv2/opencv.hpp"   
#include"opencv2/xfeatures2d.hpp" 

using namespace cv;
using namespace std;
using namespace xfeatures2d;
int labelTargets(Mat &src, Mat &mask, int thresh = 100);
int main() {
	char fn[] = "C:\\opencv\\sources\\samples\\data\\vtest.avi";
	VideoCapture capture(fn);
	Mat img, foreGround, backGround, fgMask;
	Ptr<BackgroundSubtractor>pBgModel = createBackgroundSubtractorMOG2().dynamicCast<BackgroundSubtractor>();
	if (!capture.isOpened())
	{
		cout << "无法打开视频" << fn << endl;
	}
	double rate = capture.get(CV_CAP_PROP_FPS);
	bool stop(false);
	Mat frame;
	int delay = 1000 / rate;
	while (!stop) {
		if (!capture.read(frame))
			break;
		resize(frame, img, Size(frame.cols / 2, frame.rows / 2), INTER_LINEAR);
		if (foreGround.empty()) {
			foreGround.create(img.size(), img.type());
		}
		pBgModel->apply(img, fgMask);
		threshold(fgMask, fgMask, 128, 255, THRESH_BINARY);
		foreGround = Scalar::all(0);
		img.copyTo(foreGround, fgMask);
		int nTargets = labelTargets(img, fgMask);
		pBgModel->getBackgroundImage(backGround);
		imshow("source", img);
		imshow("foreground", foreGround);
		imshow("mask", fgMask);
		imshow("background", backGround);
		cout << "共检测到" << nTargets << "个目标" << endl;
		char key = waitKey(delay);
		if (key==27)
			stop = true;
	}
	capture.release();
	waitKey();
}
int labelTargets(Mat &src, Mat &mask, int thresh) {
	Mat seg = mask.clone();
	vector<vector<Point>> cnts;
	findContours(seg, cnts, RETR_EXTERNAL, CHAIN_APPROX_SIMPLE);
	float area;
	Rect rect;
	int count = 0;
	string strCount;
	for (int i = cnts.size() - 1; i >= 0; i--) {
		vector<Point>c = cnts[i];
		area = contourArea(c);
		if (area < thresh)
			continue;
		count++;
		rect = boundingRect(c);
		rectangle(src, rect, Scalar(0, 0, 0xff), 1);
		stringstream ss;
		ss << count;
		ss >> strCount;
		putText(src, strCount, Point(rect.x, rect.y), CV_FONT_HERSHEY_PLAIN, 0.5, Scalar(0, 0xff, 0));
		
	}
	return count;
}
```
## 效果
![img](高斯提取背景.png)
# 光流估计
## 代码
```c++
#include "pch.h"
#include <iostream>
#include "opencv2/opencv.hpp"   
#include"opencv2/xfeatures2d.hpp" 
using namespace cv;
using namespace std;
using namespace xfeatures2d;
int main()
{
	char fn[] = "C:\\opencv\\sources\\samples\\data\\vtest.avi";
	VideoCapture capture(fn);
	Mat source, gray, lastgray, result;
	vector<Point2f> points[2], temp;
	vector<uchar> status;
	vector<float>err;
	bool stop(false);
	int MAX_POINT_POINTS = 100;
	while (!stop) {
		if (!capture.read(source))
			break;
		cvtColor(source, gray, COLOR_BGR2GRAY);
		if (points[0].size() < 10) {
			goodFeaturesToTrack(gray, points[0], MAX_POINT_POINTS, 0.01, 20);
		}
		if (lastgray.empty()) {
			gray.copyTo(lastgray);
		}
		calcOpticalFlowPyrLK(lastgray, gray, points[0], points[1], status, err);
		int counter = 0;
		source.copyTo(result);
		for (int i = 0; i < points[1].size(); i++) {
			line(result, points[0][i], points[1][i], Scalar(0, 0, 0xff));
			circle(result, points[1][i], 3, Scalar(0, 0, 0xff));
		}
		swap(points[0], points[1]);
		swap(lastgray, gray);
		imshow("原图像", source);
		imshow("结果", result);
		char key = waitKey(1000);
		if (key == 27) {
			break;
		}
	}
}
```
## 效果
![img2](光流估计.png)