Opencv finding the intersection of two regions

One 、 article 1

https://blog.csdn.net/lingyunxianhe/article/details/104948684/

Algorithm for solving the area of the intersection area of two polygons. Some levels found on the Internet are uneven , But the algorithms are roughly the same , It is to calculate the intersection of polygon segments and find the intersection , Then find the overlapping area . Find some good programs in the search algorithm and code , Put them together here .

1、https://github.com/abreheret/polygon-intersection

       Simple algo to find convex polygon intersection and compute area of polygone with using OpenCV

      First put a picture of the operation ：  

 

This ui The interface can interact with the mouse , Drag the polygon , Dynamically view the overlapping area . This is done very well .

2、https://github.com/LazyVinh/convex-polygon-intersection

A rather simple algorithm for intersecting to polygons in the 2D space

First put a picture of the operation ：

 

This project is also done very well , It can generate different polygons randomly . And the code is simple , It is very suitable for combing algorithm principles .

3、https://www.cnblogs.com/kannyi/p/10734255.html

This is a blog use c Program to solve the intersection area of polygons , Can compile through , It can also run , But the result is wrong .

stay github On the search polygon intersect Find a better project 1 and 2 These two , The other is either this problem or that problem .

Now I use it myself opencv The area of the intersection area of two polygons in an image is solved

because opencv There is no algorithm or program to directly find the intersection of two polygons , Here I use the particularity of solving the problem and use other function combinations to solve this problem

import os
import json
import cv2
import numpy as np
 
# Get polygons from dimension files
def GetPolygon(AnnotPath):
    with open(AnnotPath,'r') as FId:
        AnnotInfo=json.load(FId)
 
    shapes=AnnotInfo['shapes']
    Polygon1=np.array(shapes[0]['points']).astype(int)
    Polygon2=np.array(shapes[1]['points']).astype(int)
    ImH=AnnotInfo["imageHeight"]
    ImW=AnnotInfo["imageWidth"]
 
    return ImH,ImW,Polygon1,Polygon2
 
 
def DrawPolygon(ImShape,Polygon,Color):
    Im = np.zeros(ImShape, np.uint8)
    try:
        cv2.fillPoly(Im, Polygon, Color)  # Using only this function may cause errors , I don't know why
    except:
        try:
            cv2.fillConvexPoly(Im, Polygon, Color)
        except:
            print('cant fill\n')
 
    return Im
 
 
def Get2PolygonIntersectArea(ImShape,Polygon1,Polygon2):
    Im1 =DrawPolygon(ImShape[:-1],Polygon1,122)# polygon 1 Area fill as 122
    Im2 =DrawPolygon(ImShape[:-1], Polygon2, 133)# polygon 2 Area fill as 133
    Im = Im1 + Im2
    ret, OverlapIm = cv2.threshold(Im, 200, 255, cv2.THRESH_BINARY)# According to the filling value above , Therefore, the pixel value in the new image is 255 It's the overlap
    IntersectArea=np.sum(np.greater(OverlapIm, 0))# Calculate the area of the overlapping area of two polygons
 
    # Use opencv Find the function that comes with it , The best contrast
    contours, hierarchy = cv2.findContours(OverlapIm,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
    contourArea=cv2.contourArea(contours[0])
    print('contourArea={}\n'.format(contourArea))
    perimeter = cv2.arcLength(contours[0], True)
    print('contourPerimeter={}\n'.format(perimeter))
    RealContourArea=contourArea+perimeter
    print('RealContourArea={}\n'.format(RealContourArea))
    return IntersectArea,OverlapIm
 
 
if __name__ == '__main__':
    AnnotPath='./test.json'
    ImH,ImW,Polygon1,Polygon2=GetPolygon(AnnotPath)
    ImShape=(ImH,ImW,3)
    Im1 = DrawPolygon(ImShape, Polygon1, (255, 0, 0))
    Im2 = DrawPolygon(ImShape, Polygon2, (0, 255, 0))
    cv2.imshow('ColorPolygons', Im1 + Im2)
 
    IntersectArea,OverlapIm=Get2PolygonIntersectArea(ImShape, Polygon1, Polygon2)
    print('IntersectArea={}\n'.format(IntersectArea))
    cv2.imshow('OverlapIm', OverlapIm)
    cv2.waitKey(0)

The first color picture shows two polygon areas , The second is the overlapping area
————————————————
Copyright notice ： This paper is about CSDN Blogger 「 Sparkling Qi 」 The original article of , follow CC 4.0 BY-SA Copyright agreement , For reprint, please attach the original source link and this statement .
Link to the original text ：https://blog.csdn.net/lingyunxianhe/article/details/104948684/

 

Two 、 article 2

https://sxj731533730.blog.csdn.net/article/details/106818499

#include <opencv2/opencv.hpp>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
 
using namespace std;
using namespace cv;
 
int main() {
    //Mat test = imread("/home/ubuntu/CLionProjects/test/1.jpg");
    Mat img = Mat::zeros(Size(400, 400), CV_8UC1);
    Rect rec(100, 100, 100, 100);
    img(rec) = Scalar(255, 255, 255);
    imshow("img1", img);
    Mat img1 = Mat::zeros(Size(400, 400), CV_8UC1);
    Rect rec1(170, 150, 130, 120);
    img1(rec1) = Scalar(255, 255, 255);
    imshow("img2", img1);
 
    Mat dst = Mat::zeros(Size(400, 400), CV_8UC1);;
    bitwise_and(img, img1, dst);
    int iVal255 = countNonZero(dst);
    cout << " The area of the intersection ratio is " << iVal255 << endl;
    imshow("and", dst);
 
    waitKey(0);
    return 0;
}

 

3、 ... and 、 article 3

https://www.cnblogs.com/dwdxdy/p/3232110.html

https://download.csdn.net/download/qq_24038299/10260393