如何利用OpenCV实现四角点图像裁剪？

Question

cv::Mat CVSquares::detectedSquaresInImage (cv::Mat image, float tol, int threshold, int levels, int acc)
{
    vector<vector<Point> > squares;

    if( image.empty() )
        {
        cout << "CVSquares.m: Couldn't load " << endl;
        }

    tolerance = tol;
    thresh = threshold;
    N = levels;
    accuracy = acc;
    findSquares(image, squares);
    //drawSquares(image, squares);

    // The largest of them probably represents the paper
    vector<Point> largest_square;
    find_largest_square(squares, largest_square);
    drawSquares(image, largest_square);

    // Print the x,y coordinates of the square
    cout << "Point 1: " << largest_square[0] << endl;
    cout << "Point 2: " << largest_square[1] << endl;
    cout << "Point 3: " << largest_square[2] << endl;
    cout << "Point 4: " << largest_square[3] << endl;

    return image;
}

duplicate symbol __Z9getCenterNSt3__16vectorIN2cv6Point_IiEENS_9allocatorIS3_EEEE in:
    /Users/user/Library/Developer/Xcode/DerivedData/OpenCVSquares-gbnzjrefuxhjlchibreeqqdoaiqq/Build/Intermediates/OpenCVSquares.build/Debug-iphonesimulator/OpenCVSquares.build/Objects-normal/i386/UIImage+OpenCV.o
    /Users/user/Library/Developer/Xcode/DerivedData/OpenCVSquares-gbnzjrefuxhjlchibreeqqdoaiqq/Build/Intermediates/OpenCVSquares.build/Debug-iphonesimulator/OpenCVSquares.build/Objects-normal/i386/CVSquares.o
duplicate symbol __Z25sortSquarePointsClockwiseNSt3__16vectorIN2cv6Point_IiEENS_9allocatorIS3_EEEE in:
    /Users/user/Library/Developer/Xcode/DerivedData/OpenCVSquares-gbnzjrefuxhjlchibreeqqdoaiqq/Build/Intermediates/OpenCVSquares.build/Debug-iphonesimulator/OpenCVSquares.build/Objects-normal/i386/UIImage+OpenCV.o
    /Users/user/Library/Developer/Xcode/DerivedData/OpenCVSquares-gbnzjrefuxhjlchibreeqqdoaiqq/Build/Intermediates/OpenCVSquares.build/Debug-iphonesimulator/OpenCVSquares.build/Objects-normal/i386/CVSquares.o
ld: 2 duplicate symbols for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

$ c++filt __Z9getCenterNSt3__16vectorIN2cv6Point_IiEENS_9allocatorIS3_EEEE

getCenter（标准::__1::Vector,标准::__1::Allocator>>)

$ c++++filt __Z25sortSquarePointsClockwiseNSt3__16vectorIN2cv6Point_IiEENS_9allocatorIS3_EEEE

顺时针方向的sortsquarePoint(std::__1::Vector,std::__1::Allocator>>)

这是一个链接错误。它建议您将上述每个函数定义两次。