RotatedRect 的 OpenCV 最小直立边界矩形答案

【问题标题】：OpenCV minimum upright bounding rect of a RotatedRectRotatedRect 的 OpenCV 最小直立边界矩形
【发布时间】：2015-12-31 10:42:25
【问题描述】：

我正在尝试确定旋转矩形的最小边界矩形。我尝试了几个示例，例如来自 RotatedRect 参考的this 或来自this 关于椭圆和边界框的教程。没有什么令人满意的结果。在下图中，黄色矩形是所需的结果。

我的测试的示例数据：

Image:
    Width: 1500
    Height: 843

RotatedRect:
    Center:
        X: 783.490417
        Y: 433.673492
    Size:
        Width: 810.946899
        Height: 841.796997
    Angle: 95.4092407

示例代码：

cv::RotatedRect r(cv::Point2f(783.490417, 433.673492), 
    cv::Size2f(810.946899, 841.796997), 
    95.4092407);

cv::Mat img = Mat::zeros(843, 1500, CV_8UC3);

cv::Rect rect  = r.boundingRect();
cv::ellipse(img, r, cv::Scalar(0, 0, 255)); // RED

Point2f vertices[4];
r.points(vertices);

for (int i = 0; i < 4; i++)
    line(img, vertices[i], vertices[(i + 1) % 4], Scalar(0, 255, 0)); // GREEN

rectangle(img, rect, Scalar(255, 0, 0)); // BLUE
cv::imshow("Result", img);

RED - 计算最小边界矩形的 RotatedRect
蓝色 - r.boundingRect()
绿色 - r.points()
黄色 - 想要的结果

【问题讨论】：

标签： c++ opencv bounding-box

【解决方案1】：

我认为here 你可以找到一个函数来实现你想要的结果。

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"


using namespace cv;

int main( int argc, char**)
{
    RotatedRect r ;
    r.center =  cv::Point2f(783.490417, 433.673492);
    r.angle = 95.4092407;
    r.size = cv::Size2f(810.946899, 841.796997);

    cv::Mat img = Mat::zeros(843, 1500, CV_8UC3);

    cv::Rect rect  = r.boundingRect();
    cv::ellipse(img, r, cv::Scalar(0, 0, 255)); // RED

    Point2f vertices[4];
    r.points(vertices);

    for (int i = 0; i < 4; i++)
        line(img, vertices[i], vertices[(i + 1) % 4], Scalar(0, 255, 0)); // GREEN

    rectangle(img, rect, Scalar(255, 0, 0)); // BLUE


    float degree = r.angle*3.1415/180;
    float majorAxe = r.size.width/2;
    float minorAxe = r.size.height/2;
    float x = r.center.x;
    float y = r.center.y;
    float c_degree = cos(degree);
    float s_degree = sin(degree);
    float t1 = atan(-(majorAxe*s_degree)/(minorAxe*c_degree));
    float c_t1 = cos(t1);
    float s_t1 = sin(t1);
    float w1 = majorAxe*c_t1*c_degree;
    float w2 = minorAxe*s_t1*s_degree;
    float maxX = x + w1-w2;
    float minX = x - w1+w2;

    t1 = atan((minorAxe*c_degree)/(majorAxe*s_degree));
    c_t1 = cos(t1);
    s_t1 = sin(t1);
    w1 = minorAxe*s_t1*c_degree;
    w2 = majorAxe*c_t1*s_degree;
    float maxY = y + w1+w2;
    float minY = y - w1-w2;
    if (minY > maxY)
    {
        float temp = minY;
        minY = maxY;
        maxY = temp;
    }
    if (minX > maxX)
    {
        float temp = minX;
        minX = maxX;
        maxX = temp;
    }
    Rect yellowrect(minX,minY,maxX-minX+1,maxY-minY+1);

    rectangle(img, yellowrect, Scalar(0, 255, 255)); // YELLOW
    cv::imshow("Result", img);
    waitKey();
}

【讨论】：