vivek_annem's profile - activity

I am trying to find the transformation matrix H so that i can multiply the (x,y) pixel coordinates and get the (x,y) real world coordinates. Here is my code:

import cv2
import numpy as np
from numpy.linalg import inv
if __name__ == '__main__' :
    D=[159.1,34.2]
    I=[497.3,37.5]
    G=[639.3,479.7]
    A=[0,478.2]
    # Read source image.
    im_src = cv2.imread('/home/vivek/june_14.png')
    # Four corners of the book in source image
    pts_src = np.array([D,I,G,A])

    # Read destination image.
    im_dst = cv2.imread('/home/vivek/june_14.png')

    # Four corners of the book in destination image.
    print "img1 shape:",im_dst.shape
    scale=1
    O=[0.0,0.0]
    X=[134.0*scale,0]
    Y=[0.0,184.0*scale]
    P=[134.0*scale,184.0*scale]
    # lx = 75.5 * scale
    # ly = 154.0 * scale
    pts_dst = np.array([O,X,P,Y])

    # Calculate Homography
    h, status = cv2.findHomography(pts_src, pts_dst)

    print "homography:",h
    print "inv of H:",inv(h)
    print "position of the blob on the ground xy plane:",np.dot(np.dot(h,np.array([[323.0],[120.0],[1.0]])),scale)


    # Warp source image to destination based on homography

    im_out = cv2.warpPerspective(im_src, h, (im_dst.shape[1],im_dst.shape[0]))

    # Display images
    cv2.imshow("Source Image", im_src)
    cv2.imshow("Destination Image", im_dst)
    cv2.imshow("Warped Source Image", im_out)
    cv2.imwrite("im_out.jpg", im_out)
    cv2.waitKey(0)

The values I am currently getting look way off. Am i doing something wrong?