计算点之间的角度 [英] Calculating the angle between Points

问题描述

使用C ++和opencv

Working with C++ and opencv

我试图计算两点之间的角度...我有一个2D平面，边界框，现在如果框架1中的中心点已经改变其在框架2中的位置，我需要找到这两个点的角度。

I am trying to calculate an angle between two points.....I have a 2D plane with a changing center point of a bounding box, Now if the center point in frame 1 has changed its location in frame 2 i need to find the angle of these two points.

这是我想要做的例子：

有人可以建议一种工作方式。 ...？某些数学解决方案或者可能是C ++函数。

Can someone suggest a way of working this out.......? some kind of mathematical solution or perhaps a C++ function.

推荐答案

使用点击产品：

v1.v2 = v1.x * v2.x + v1.y * v2.y

v1.v2 = |v1| * |v2| * cos(theta)
---------------------------------+
                                 |
                                 +-->  theta = acos(v1.v2 / |v1|*|v2|)

示例代码是：

float angleBetween(const Point &v1, const Point &v2)
{
    float len1 = sqrt(v1.x * v1.x + v1.y * v1.y);
    float len2 = sqrt(v2.x * v2.x + v2.y * v2.y);

    float dot = v1.x * v2.x + v1.y * v2.y;

    float a = dot / (len1 * len2);

    if (a >= 1.0)
        return 0.0;
    else if (a <= -1.0)
        return PI;
    else
        return acos(a); // 0..PI
}

它计算v1和v2之间的角度如下图

It calculates angle between v1 and v2 as below image

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