Hi all,
I am carrying out an undergraduate where I need to find out the depth of a stereo image, thus it is crucial to get a good disparity map for the calculations to be accurate. My rectification results are pretty mediocre at best and I have carried out the calibration countless times with no success, only minimal variations between results. I would highly appreciate experts' guidance on this issue. Like, can I try changing some parameters of my stereoRectify method? I already tried to tinker with the stereocalibrate parameters with minimal success.
I cannot post my results on this question as I have insufficient karma, but the rectified images look as if they were warped in a spiral manner and overriding the original video capture. Copy this in the URL if you wish to see a sample of my results: scontent.fmla1-2.fna.fbcdn.net/v/t35.0-12/17571001_10212528106338046_845875913_o.png?oh=3ef04efa50a3d9f4e4d253f2f57ae298&oe=58DAF735
This is my code for the calibration:
import cv,time,sys
import cv2
from itertools import izip
# python calibrate.py board_w,board_h and boards_n should be given by the user
n_boards=0 #no of boards
board_w=int(sys.argv[1]) # number of horizontal corners
board_h=int(sys.argv[2]) # number of vertical corners
n_boards=int(sys.argv[3]) # no. of views passed as pictures
board_n=board_w*board_h # no of total corners
board_sz=(board_w,board_h) # size of board
# creation of memory storages for left camera
image_points0=cv.CreateMat(n_boards*board_n,2,cv.CV_32FC1)
object_points=cv.CreateMat(n_boards*board_n,3,cv.CV_32FC1)
point_counts=cv.CreateMat(n_boards,1,cv.CV_32SC1)
intrinsic_matrix0=cv.CreateMat(3,3,cv.CV_32FC1)
distortion_coefficient0=cv.CreateMat(5,1,cv.CV_32FC1)
# creation of memory storages for right camera
image_points1=cv.CreateMat(n_boards*board_n,2,cv.CV_32FC1)
intrinsic_matrix1=cv.CreateMat(3,3,cv.CV_32FC1)
distortion_coefficient1=cv.CreateMat(5,1,cv.CV_32FC1)
R=cv.CreateMat(3,3,cv.CV_64F)
T=cv.CreateMat(3,1,cv.CV_64F)
E=cv.CreateMat(3,3,cv.CV_64F)
F=cv.CreateMat(3,3,cv.CV_64F)
#term_crit=(cv.CV_TERMCRIT_EPS+cv.CV_TERMCRIT_ITER,30,0.1)
#capture frames of specified properties and modification of matrix values
i=0
z=0 # to print number of frames
successes=0
# capturing required number of views
found=0
with open('Left.txt','rb') as f:
imgl= [line.strip() for line in f]
with open('Right.txt','rb') as f1:
imgr=[line.strip() for line in f1]
for (image0,image1) in izip(imgl,imgr):
if image0 =='' or image1== '' :
break;
else:
Image0 = cv.LoadImage(image0)
Image1 = cv.LoadImage(image1)
gray_image0=cv.CreateImage(cv.GetSize(Image0),8,1)
cv.CvtColor(Image0,gray_image0,cv.CV_BGR2GRAY)
gray_image1=cv.CreateImage(cv.GetSize(Image1),8,1)
cv.CvtColor(Image1,gray_image1,cv.CV_BGR2GRAY)
(found0,corners0)=cv.FindChessboardCorners(gray_image0,board_sz,cv.CV_CALIB_CB_ADAPTIVE_THRESH| cv.CV_CALIB_CB_FILTER_QUADS)
(found1,corners1)=cv.FindChessboardCorners(gray_image1,board_sz,cv.CV_CALIB_CB_ADAPTIVE_THRESH| cv.CV_CALIB_CB_FILTER_QUADS)
cv.FindCornerSubPix(gray_image0,corners0,(11,11),(-1,-1),(cv.CV_TERMCRIT_EPS+cv.CV_TERMCRIT_ITER,30,0.001))
cv.FindCornerSubPix(gray_image1,corners1,(11,11),(-1,-1),(cv.CV_TERMCRIT_EPS+cv.CV_TERMCRIT_ITER,30,0.001))
# if got a good image,draw chess board
if found0==1 and found1==1:
print "found frame number {0}".format(z+1)
cv.DrawChessboardCorners(Image0,board_sz,corners0,1)
cv.DrawChessboardCorners(Image1,board_sz,corners1,1)
cv.ShowImage("Left cam corners",Image0);
cv.ShowImage("Right cam corners",Image1);
cv.WaitKey(33)
corner_count0=len(corners0)
corner_count1=len(corners1)
print "corner count0",corner_count0
print "corner count1",corner_count1
z=z+1
# if got a good image, add to matrix
if len(corners0)==board_n and len(corners1)==board_n:
step=successes*board_n
k=step
for j in range(board_n):
cv.Set2D(image_points0,k,0,corners0[j][0])
cv.Set2D(image_points0,k,1,corners0[j][1])
cv.Set2D(image_points1,k,0,corners1[j][0])
cv.Set2D(image_points1,k,1,corners1[j][1])
cv.Set2D(object_points,k,0,float(j)/float(board_w))
cv.Set2D(object_points,k,1,float(j)%float(board_w))
cv.Set2D(object_points,k,2,0.0)
k=k+1
cv.Set2D(point_counts,successes,0,board_n)
successes=successes+1
print successes
time.sleep(2)
print "-------------------------------------------------"
print "\n"
print "Calibration OK, Matrices Created"
cv.DestroyWindow("Test Frame")
# now assigning new matrices according to view_count
object_points2=cv.CreateMat(successes*board_n,3,cv.CV_32FC1)
image_points20=cv.CreateMat(successes*board_n,2,cv.CV_32FC1)
image_points21=cv.CreateMat(successes*board_n,2,cv.CV_32FC1)
point_counts2=cv.CreateMat(successes,1,cv.CV_32SC1)
#transfer points to matrices
for i in range(successes*board_n):
cv.Set2D(image_points20,i,0,cv.Get2D(image_points0,i,0))
cv.Set2D(image_points20,i,1,cv.Get2D(image_points0,i,1))
cv.Set2D(image_points21,i,0,cv.Get2D(image_points1,i,0))
cv.Set2D(image_points21,i,1,cv.Get2D(image_points1,i,1))
cv.Set2D(object_points2,i,0,cv.Get2D(object_points,i,0))
cv.Set2D(object_points2,i,1,cv.Get2D(object_points,i,1))
cv.Set2D(object_points2,i,2,cv.Get2D(object_points,i,2))
for i in range(successes):
cv.Set2D(point_counts2,i,0,cv.Get2D(point_counts,i,0))
cv.Set2D(intrinsic_matrix0,0,0,1.0)
cv.Set2D(intrinsic_matrix0,1,1,1.0)
cv.Set2D(intrinsic_matrix1,0,0,1.0)
cv.Set2D(intrinsic_matrix1,1,1,1.0)
print "Checking Camera Calibration"
# camera calibration
#cv.StereoCalibrate(object_points2,image_points20,image_points21,point_counts2,intrinsic_matrix0,
#distortion_coefficient0,intrinsic_matrix1,distortion_coefficient1,cv.GetSize(Image0),R,T,E,F,
#(cv.CV_TERMCRIT_ITER+cv.CV_TERMCRIT_EPS, 30, 1e-6), (cv.CV_CALIB_SAME_FOCAL_LENGTH+cv.CV_CALIB_ZERO_TANGENT_DIST+cv.CV_CALIB_FIX_FOCAL_LENGTH ))
cv.StereoCalibrate(object_points2,image_points20,image_points21,point_counts2,intrinsic_matrix0,
distortion_coefficient0,intrinsic_matrix1,distortion_coefficient1,cv.GetSize(Image0),R,T,E,F,
(cv2.TERM_CRITERIA_MAX_ITER + cv2.TERM_CRITERIA_EPS, 100, 1e-5), (cv2.CALIB_FIX_ASPECT_RATIO + cv2.CALIB_ZERO_TANGENT_DIST + cv2.CALIB_SAME_FOCAL_LENGTH+
cv.CV_CALIB_FIX_K1+
cv.CV_CALIB_FIX_K2+
cv.CV_CALIB_FIX_K3))
print "Calibration Successful"
# storing results in xml files
cv.Save("Image points1.xml",image_points20)
cv.Save("Image points2.xml",image_points21)
cv.Save("Intrinsics0.xml",intrinsic_matrix0)
cv.Save("Distortion0.xml",distortion_coefficient0)
cv.Save("Intrinsics1.xml",intrinsic_matrix1)
cv.Save("Distortion1.xml",distortion_coefficient1)
cv.Save("R.xml",R)
cv.Save("T.xml",T)
This is my code for the rectification:
import cv
import time
import numpy as np
def stereorectify(image0,image1):
# Loading matrices output from the calibration step
intrinsic0=cv.Load("Intrinsics0.xml")
distortion0=cv.Load("Distortion0.xml")
intrinsic1=cv.Load("Intrinsics1.xml")
distortion1=cv.Load("Distortion1.xml")
R=cv.Load("R.xml")
T=cv.Load("T.xml")
# Rectification
Ro=cv.CreateMat(3,1,cv.CV_64F);
cv.Rodrigues2(R, Ro)
size=cv.GetSize(image0)
R1=cv.CreateMat(3,3,cv.CV_64F)
R2=cv.CreateMat(3,3,cv.CV_64F)
P1=cv.CreateMat(3,4,cv.CV_64F)
P2=cv.CreateMat(3,4,cv.CV_64F)
#Q=cv.CreateMat(4,4,cv.CV_64F)
height,width=240, 320
focal_length=0.8*width
Q = np.float32([[1, 0, 0, -0.5 * width],
[0, -1, 0, 0.5 * height],
[0, 0, 0, -focal_length],
[0, 0, 1, 0]])
flags=cv.CV_CALIB_ZERO_DISPARITY
#cv.StereoRectify(intrinsic0, intrinsic1, distortion0,distortion1,(320,240),R,T,R2, R1, P1,P2, cv.fromarray(Q) ,0,0)
cv.StereoRectify(intrinsic0, intrinsic1, distortion0,distortion1,(640,480),R,T,R2, R1, P1,P2, cv.fromarray(Q) ,0,0)
#print newImageSize
map1x = cv.CreateImage(size, cv.IPL_DEPTH_32F,1)
map2x = cv.CreateImage(size, cv.IPL_DEPTH_32F,1)
#Right maps
map1y = cv.CreateImage(size, cv.IPL_DEPTH_32F,1)
map2y = cv.CreateImage(size, cv.IPL_DEPTH_32F,1)
# Undistorting/ Rectification
cv.InitUndistortRectifyMap(intrinsic0, distortion0, R1, intrinsic0, map1x, map1y)
cv.InitUndistortRectifyMap(intrinsic1, distortion1, R2, intrinsic1,map2x, map2y)
cv.InitUndistortRectifyMap(intrinsic0, distortion0, R1, intrinsic0, map1x, map1y)
cv.InitUndistortRectifyMap(intrinsic1, distortion1, R2, intrinsic1,map2x, map2y)
cv.Remap(image0,image0, map1x, map1y,cv.CV_INTER_CUBIC)
cv.Remap(image1,image1, map2x, map2y,cv.CV_INTER_CUBIC)
cv.Save("R1.xml",R1);
cv.Save("map1x.xml",map1x);
#cv.Save("Q.xml",Q)
return image0,image1
I would appreciate any help which could aid me in yielding better results as I feel I've hit a dead end and cannot improve. Thanks!!
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