Camera Calibration

Author: abidrahmank

Other_Examples/camera_calibration.py

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+'''	 camera_calibration.py
+
+Usage:	python camera_calibration.py board_w board_h number_of_views
+	
+This program reads a chessboard's width and height, collects requested number of views and calibrates the camera.
+
+This is a little modified version of the example 11-1 given in the book "Learning OpenCV: Computer Vision with the OpenCV Library". 
+
+Converted to Python by Abid.K	--mail me at [email protected]	
+
+'''
+
+################################################################################################
+
+import cv,time,sys
+
+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])
+board_n=board_w*board_h		# no of total corners
+board_sz=(board_w,board_h)	#size of board
+
+
+
+
+#	creation of memory storages
+image_points=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_matrix=cv.CreateMat(3,3,cv.CV_32FC1)
+distortion_coefficient=cv.CreateMat(5,1,cv.CV_32FC1)
+
+#	capture frames of specified properties and modification of matrix values
+i=0
+z=0		# to print number of frames
+successes=0
+capture=cv.CaptureFromCAM(0)
+#	capturing required number of views
+while(successes<n_boards):
+	found=0
+	image=cv.QueryFrame(capture)
+	gray_image=cv.CreateImage(cv.GetSize(image),8,1)
+	cv.CvtColor(image,gray_image,cv.CV_BGR2GRAY)
+	
+	(found,corners)=cv.FindChessboardCorners(gray_image,board_sz,cv.CV_CALIB_CB_ADAPTIVE_THRESH| cv.CV_CALIB_CB_FILTER_QUADS)
+	corners=cv.FindCornerSubPix(gray_image,corners,(11,11),(-1,-1),(cv.CV_TERMCRIT_EPS+cv.CV_TERMCRIT_ITER,30,0.1)) 	
+	# if got a good image,draw chess board
+	if found==1:
+		print "found frame number {0}".format(z+1)
+		cv.DrawChessboardCorners(image,board_sz,corners,1) 
+		corner_count=len(corners)
+		z=z+1
+		
+	# if got a good image, add to matrix
+	if len(corners)==board_n:
+		step=successes*board_n
+		k=step
+		for j in range(board_n):
+			cv.Set2D(image_points,k,0,corners[j][0])
+			cv.Set2D(image_points,k,1,corners[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
+		time.sleep(2)
+		print "-------------------------------------------------"
+		print "\n"
+	cv.ShowImage("Test Frame",image)
+	cv.WaitKey(33)
+
+print "checking is fine	,all matrices are 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_points2=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_points2,i,0,cv.Get2D(image_points,i,0))
+	cv.Set2D(image_points2,i,1,cv.Get2D(image_points,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_matrix,0,0,1.0)
+cv.Set2D(intrinsic_matrix,1,1,1.0)
+
+rcv = cv.CreateMat(n_boards, 3, cv.CV_64FC1)
+tcv = cv.CreateMat(n_boards, 3, cv.CV_64FC1)
+
+print "checking camera calibration............."
+# camera calibration
+cv.CalibrateCamera2(object_points2,image_points2,point_counts2,cv.GetSize(image),intrinsic_matrix,distortion_coefficient,rcv,tcv,0)
+print " checking camera calibration.........................OK	"	
+	
+# storing results in xml files
+cv.Save("Intrinsics.xml",intrinsic_matrix)
+cv.Save("Distortion.xml",distortion_coefficient)
+# Loading from xml files
+intrinsic = cv.Load("Intrinsics.xml")
+distortion = cv.Load("Distortion.xml")
+print " loaded all distortion parameters"
+
+mapx = cv.CreateImage( cv.GetSize(image), cv.IPL_DEPTH_32F, 1 );
+mapy = cv.CreateImage( cv.GetSize(image), cv.IPL_DEPTH_32F, 1 );
+cv.InitUndistortMap(intrinsic,distortion,mapx,mapy)
+cv.NamedWindow( "Undistort" )
+print "all mapping completed"
+print "Now relax for some time"
+time.sleep(8)
+
+print "now get ready, camera is switching on"
+while(1):
+	image=cv.QueryFrame(capture)
+	t = cv.CloneImage(image);
+	cv.ShowImage( "Calibration", image )
+	cv.Remap( t, image, mapx, mapy )
+	cv.ShowImage("Undistort", image)
+	c = cv.WaitKey(33)
+	if(c == 1048688):		# enter 'p' key to pause for some time
+		cv.WaitKey(2000)
+	elif c==1048603:		# enter esc key to exit
+		break
+		
+print "everything is fine"
+
+###############################################################################################