OpenCV计算卫星云图大致面积及周长
一、概述
案例:使用OpenCV实现卫星云图的周长面积计算
实现步骤:
1.输入图像
2.对图像进行高斯模糊,主要是为了降噪
3.图像灰度化
4.图像二值分割
5.执行形态学操作去除小点并使对象黏连
6.轮廓发现,并过滤目标轮廓
7.计算轮廓周长及面积
8.输出目标图像,并在目标图像上显示周长及面积
二、代码示例
//【1】载入图像 Mat src = imread(filePath); if(src.empty()){ qDebug()<<"图片为空"; return; } imshow("src",src); //【2】高斯模糊去除噪声 GaussianBlur(src,src,Size(15,15),0,0); //【3】图像灰度化 Mat gray; cvtColor(src,gray,COLOR_BGR2GRAY); //【4】二值分割 threshold(gray,gray,0,255,THRESH_BINARY|THRESH_TRIANGLE); imshow("threshold",gray); //【5】执行形态学开操作 Mat kernel = getStructuringElement(MORPH_RECT,Size(3,3),Point(-1,-1)); morphologyEx(gray,gray,MORPH_OPEN,kernel,Point(-1,-1),2); imshow("morphologyEX",gray); //【6】发现轮廓 vector<vector<Point>> contours; vector<Vec4i> hier; findContours(gray,contours,hier,RETR_TREE,CHAIN_APPROX_SIMPLE); RNG rng(123456); Mat resultImage = Mat::zeros(src.size(),CV_8UC3); for(size_t i = 0;i<contours.size();i++){ Rect rect = boundingRect(contours[i]); if(rect.width>src.cols/2&&rect.height>src.rows/3){ Scalar scalar = Scalar(rng.uniform(0,255),rng.uniform(0,255),rng.uniform(0,255)); drawContours(resultImage,contours,i,scalar,-1,LINE_8); //【7】计算面积,周长 double area = contourArea(contours[i],false); double length = arcLength(contours[i],false); QString str; str = QString("area:%1,length:%2").arg(area).arg(length); putText(resultImage,str.toStdString(),Point(src.cols/3,src.rows/2),FONT_HERSHEY_PLAIN,1,Scalar(255,255,255)); qDebug()<<"面积:"<<area; qDebug()<<"周长:"<<length; } } //【输出目标图像】 imshow("resultImage",resultImage);
三、示例图片