单应性矩阵应用

一. 图像矫正

#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;

struct userdata{
    Mat im;
    vector<Point2f> points;
};

void mouseHandler(int event, int x, int y, int flags, void* data_ptr)
{
    if  ( event == EVENT_LBUTTONDOWN )
    {
        userdata *data = ((userdata *) data_ptr);
        circle(data->im, Point(x,y),3,Scalar(0,0,255), 5, CV_AA);
        imshow("Image", data->im);
        if (data->points.size() < 4)
        {
            data->points.push_back(Point2f(x,y));
        }
    }

}



int main()
{

    // Read source image.
    Mat im_src = imread("1.png");

    // Destination image. The aspect ratio of the book is 3/4
    Size size(300,400);
    Mat im_dst = Mat::zeros(size,CV_8UC3);


    // Create a vector of destination points.
    vector<Point2f> pts_dst;

    pts_dst.push_back(Point2f(0,0));
    pts_dst.push_back(Point2f(size.width - 1, 0));
    pts_dst.push_back(Point2f(size.width - 1, size.height -1));
    pts_dst.push_back(Point2f(0, size.height - 1 ));

    // Set data for mouse event
    Mat im_temp = im_src.clone();
    userdata data;
    data.im = im_temp;

    cout << "Click on the four corners of the book -- top left first and" << endl
        << "bottom left last -- and then hit ENTER" << endl;

    // Show image and wait for 4 clicks. 
    imshow("Image", im_temp);
    // Set the callback function for any mouse event
    setMouseCallback("Image", mouseHandler, &data);
    waitKey(0);

    // Calculate the homography
    Mat h = findHomography(data.points, pts_dst);

    // Warp source image to destination
    warpPerspective(im_src, im_dst, h, size);

    // Show image
    imshow("Image", im_dst);
    waitKey(0);
    return 0;


}

二.虚拟广告牌

#include <opencv2/opencv.hpp>

using namespace cv;
using namespace std;

struct userdata{
    Mat im;
    vector<Point2f> points;
};


void mouseHandler(int event, int x, int y, int flags, void* data_ptr)
{
    if  ( event == EVENT_LBUTTONDOWN )
    {
        userdata *data = ((userdata *) data_ptr);
        circle(data->im, Point(x,y),3,Scalar(0,255,255), 5, CV_AA);
        imshow("Image", data->im);
        if (data->points.size() < 4)
        {
            data->points.push_back(Point2f(x,y));
        }
    }

}



int main( int argc, char** argv)
{

    // Read in the image.
    Mat im_src = imread("2.jpeg");
    Size size = im_src.size();

    // Create a vector of points.
    vector<Point2f> pts_src;
    pts_src.push_back(Point2f(0,0));
    pts_src.push_back(Point2f(size.width - 1, 0));
    pts_src.push_back(Point2f(size.width - 1, size.height -1));
    pts_src.push_back(Point2f(0, size.height - 1 ));



    // Destination image
    Mat im_dst = imread("3.jpeg");


    // Set data for mouse handler
    Mat im_temp = im_dst.clone();
    userdata data;
    data.im = im_temp;


    //show the image
    imshow("Image", im_temp);

    cout << "Click on four corners of a billboard and then press ENTER" << endl;
    //set the callback function for any mouse event
    setMouseCallback("Image", mouseHandler, &data);
    waitKey(0);

    // Calculate Homography between source and destination points
    Mat h = findHomography(pts_src, data.points);

    // Warp source image
    warpPerspective(im_src, im_temp, h, im_temp.size());

    // Extract four points from mouse data
    Point pts_dst[4];
    for( int i = 0; i < 4; i++)
    {
        pts_dst[i] = data.points[i];
    }

    // Black out polygonal area in destination image.
    fillConvexPoly(im_dst, pts_dst, 4, Scalar(0), CV_AA);

    // Add warped source image to destination image.
    im_dst = im_dst + im_temp;

    // Display image.
    imshow("Image", im_dst);
    waitKey(0);

    return 0;
}

CMakelists.txt:

cmake_minimum_required( VERSION 2.8 )
project( a )

set( CMAKE_BUILD_TYPE Release )
set( CMAKE_CXX_FLAGS "-std=c++11 -O3" )

find_package( OpenCV )
include_directories( ${OpenCV_INCLUDE_DIRS} )

add_executable( a a.cpp )
target_link_libraries( a ${OpenCV_LIBS} )

add_executable( b b.cpp )
target_link_libraries( b ${OpenCV_LIBS} )

图片下载:

                                       图片1                                                                                         图片2

                                                                                                                      图片3