写出第二种方法的示例代码
时间: 2023-08-21 19:02:46 浏览: 39
以下是通过RANSAC算法拟合圆的示例代码:
```
#include <iostream>
#include <vector>
#include <cmath>
#include <cstdlib>
#include <ctime>
using namespace std;
// 定义二维点的结构体
struct Point2D {
double x;
double y;
};
// 计算两点间的距离
double distance(const Point2D& p1, const Point2D& p2) {
return sqrt(pow(p1.x - p2.x, 2) + pow(p1.y - p2.y, 2));
}
// 计算圆心和半径
bool fitCircle(const vector<Point2D>& points, Point2D& center, double& radius) {
const int MAX_ITERATIONS = 1000; // 最大迭代次数
const double MAX_DISTANCE = 0.1; // 最大距离阈值
const int MIN_POINTS = 3; // 最小数据点数
const int size = points.size();
if (size < MIN_POINTS) {
return false;
}
srand(time(NULL)); // 随机数种子
Point2D bestCenter;
double bestRadius = 0;
double bestError = INFINITY;
for (int i = 0; i < MAX_ITERATIONS; ++i) {
// 随机选择三个点
int indices[3] = {rand() % size, rand() % size, rand() % size};
Point2D p1 = points[indices[0]];
Point2D p2 = points[indices[1]];
Point2D p3 = points[indices[2]];
// 计算圆心和半径
double x1 = p1.x, y1 = p1.y;
double x2 = p2.x, y2 = p2.y;
double x3 = p3.x, y3 = p3.y;
double A = x1*(y2-y3) - y1*(x2-x3) + x2*y3 - y2*x3;
double B = pow(x1, 2) + pow(y1, 2);
double C = pow(x2, 2) + pow(y2, 2);
double D = pow(x3, 2) + pow(y3, 2);
double E = x1*(y3-y2) + y1*(x2-x3) + x3*y2 - y3*x2;
double F = 2*(x1*(y3-y2) + y1*(x2-x3) + x3*y2 - y3*x2);
double G = 2*(x2*(y1-y3) + y2*(x3-x1) + x1*y3 - y1*x3);
double H = 2*(x3*(y2-y1) + y3*(x1-x2) + x2*y1 - y2*x1);
double x = (D*F + B*G + C*H)/(2*A*E + F*D - G*C - H*B);
double y = (A*G + E*C - B*H)/(2*A*E + F*D - G*C - H*B);
double r = distance(points[0], Point2D{x, y});
// 计算误差
double error = 0;
for (int j = 0; j < size; ++j) {
double d = distance(points[j], Point2D{x, y});
error += pow(d - r, 2);
}
// 更新最优解
if (error < bestError) {
bestCenter = Point2D{x, y};
bestRadius = r;
bestError = error;
}
// 判断是否满足距离阈值
if (bestError <= MAX_DISTANCE) {
break;
}
}
// 返回圆心和半径
center = bestCenter;
radius = bestRadius;
return true;
}
int main() {
// 构造数据点
vector<Point2D> points = {{0, 0}, {1, 1}, {2, 0}, {0, 2}, {2, 2}};
// 拟合圆
Point2D center;
double radius;
if (fitCircle(points, center, radius)) {
cout << "Center: (" << center.x << ", " << center.y << ")" << endl;
cout << "Radius: " << radius << endl;
}
else {
cout << "Error: Not enough points." << endl;
}
return 0;
}
```
以上代码使用RANSAC算法拟合圆,随机选择三个点计算圆心和半径,并重复该过程多次,选择距离平均值最小的圆作为拟合结果。可以通过修改最大迭代次数、最大距离阈值和最小数据点数等参数来控制算法的精度和速度。