OpenCV: minarea.cpp

| OpenCV 3.4.2 Open Source Computer Vision

minarea.cpp
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"
#include <iostream>
using namespace cv;
using namespace std;
static void help()
{
cout << "This program demonstrates finding the minimum enclosing box, triangle or circle of a set\n"
<< "of points using functions: minAreaRect() minEnclosingTriangle() minEnclosingCircle().\n"
<< "Random points are generated and then enclosed.\n\n"
<< "Press ESC, 'q' or 'Q' to exit and any other key to regenerate the set of points.\n\n";
}
int main( int /*argc*/, char** /*argv*/ )
{
help();
Mat img(500, 500, CV_8UC3);
RNG& rng = theRNG();
for(;;)
{
int i, count = rng. uniform(1, 101);
vector<Point> points;
// Generate a random set of points
for( i = 0; i < count; i++ )
{
Point pt;
pt. x = rng.uniform(img.cols/4, img.cols*3/4);
pt. y = rng.uniform(img.rows/4, img.rows*3/4);
points.push_back(pt);
}
// Find the minimum area enclosing bounding box
Point2f vtx[4];
RotatedRect box = minAreaRect(points);
box. points(vtx);
// Find the minimum area enclosing triangle
vector<Point2f> triangle;
minEnclosingTriangle(points, triangle);
// Find the minimum area enclosing circle
Point2f center;
float radius = 0;
minEnclosingCircle(points, center, radius);
img = Scalar::all(0);
// Draw the points
for( i = 0; i < count; i++ )
circle( img, points[i], 3, Scalar(0, 0, 255), FILLED, LINE_AA );
// Draw the bounding box
for( i = 0; i < 4; i++ )
line(img, vtx[i], vtx[(i+1)%4], Scalar(0, 255, 0), 1, LINE_AA);
// Draw the triangle
for( i = 0; i < 3; i++ )
line(img, triangle[i], triangle[(i+1)%3], Scalar(255, 255, 0), 1, LINE_AA);
// Draw the circle
circle(img, center, cvRound(radius), Scalar(0, 255, 255), 1, LINE_AA);
imshow( "Rectangle, triangle & circle", img );
char key = (char)waitKey();
if( key == 27 || key == 'q' || key == 'Q' ) // 'ESC'
break;
}
return 0;
}