319 lines
12 KiB
Python
319 lines
12 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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'''
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###########################################################################
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## CAMERAS CALIBRATION ##
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###########################################################################
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Use this module to calibrate your cameras from checkerboard images and
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save results to a .toml file.
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Based on https://docs.opencv.org/3.4.15/dc/dbb/tutorial_py_calibration.html.
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/!\ Beware that corners must be detected on all frames, or else extrinsic
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parameters may be wrong. Set show_corner_detection to 1 to verify.
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Usage:
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python -m calib_from_checkerboard -d "calib_path" -v False -e jpg -n 6 9 -S 1000
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OR python -m calib_from_checkerboard -d "calib_path" -v True -e mp4 -n 6 9 -S 1000 1000 -s 1 -O 0 -f 50 -o Test.toml
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OR from Pose2Sim.Utilities import calib_from_checkerboard; calib_from_checkerboard.calibrate_cams_func(calib_dir=r"calib_path",
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video=False, extension="jpg", corners_nb=(6,9), square_size=[1000])
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'''
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## INIT
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import os
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import numpy as np
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import cv2
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import glob
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import toml
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import argparse
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## AUTHORSHIP INFORMATION
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__author__ = "David Pagnon"
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__copyright__ = "Copyright 2021, Pose2Sim"
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__credits__ = ["David Pagnon"]
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__license__ = "BSD 3-Clause License"
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__version__ = "0.8.2"
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__maintainer__ = "David Pagnon"
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__email__ = "contact@david-pagnon.com"
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__status__ = "Development"
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## FUNCTIONS
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def euclidean_distance(q1, q2):
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'''
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Euclidean distance between 2 points (N-dim).
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INPUTS:
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- q1: list of N_dimensional coordinates of point
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- q2: idem
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OUTPUTS:
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- euc_dist: float. Euclidian distance between q1 and q2
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'''
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q1 = np.array(q1)
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q2 = np.array(q2)
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dist = q2 - q1
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euc_dist = np.sqrt(np.sum( [d**2 for d in dist] ))
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return euc_dist
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def rotate_cam(r, t, ang_x=np.pi, ang_y=0, ang_z=0):
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'''
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Apply rotations around x, y, z in cameras coordinates
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'''
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if r.shape == (3,3):
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rt_h = np.block([[r,t.reshape(3,1)], [np.zeros(3), 1 ]])
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elif r.shape == (3,):
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rt_h = np.block([[cv2.Rodrigues(r)[0],t.reshape(3,1)], [np.zeros(3), 1 ]])
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r_ax_x = np.array([1,0,0, 0,np.cos(ang_x),-np.sin(ang_x), 0,np.sin(ang_x),np.cos(ang_x)]).reshape(3,3)
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r_ax_y = np.array([np.cos(ang_y),0,np.sin(ang_y), 0,1,0, -np.sin(ang_y),0,np.cos(ang_y)]).reshape(3,3)
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r_ax_z = np.array([np.cos(ang_z),-np.sin(ang_z),0, np.sin(ang_z),np.cos(ang_z),0, 0,0,1]).reshape(3,3)
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r_ax = r_ax_z @ r_ax_y @ r_ax_x
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r_ax_h = np.block([[r_ax,np.zeros(3).reshape(3,1)], [np.zeros(3), 1]])
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r_ax_h__rt_h = r_ax_h @ rt_h
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r = r_ax_h__rt_h[:3,:3]
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t = r_ax_h__rt_h[:3,3]
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return r, t
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def findCorners(img, corners_nb, criteria, show):
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'''
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Find corners _of internal squares_ in the checkerboard
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INPUTS:
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- img: image read by opencv
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- corners_nb: [H, W] internal corners in checkerboard: list of two integers [9,6]
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- criteria: when to stop optimizing corners localization
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- show: choose whether to show corner detections
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OUTPUTS
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- imgp: 2d corner points in image plane
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'''
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# Find corners
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gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
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ret, corners = cv2.findChessboardCorners(gray, corners_nb, None)
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# Refine corners
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if ret == True:
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imgp = cv2.cornerSubPix(gray, corners, (11,11), (-1,-1), criteria)
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# Draw and display the corners
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if show:
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cv2.drawChessboardCorners(img, corners_nb, imgp, ret)
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print('Corners found.')
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cv2.imshow('img', img)
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cv2.waitKey(0)
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return imgp
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else:
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if show:
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print('Corners not found.')
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return
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def calib_checkerboard(criteria, **args):
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'''
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Calibrates from images or videos of a checkerboard
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INPUTS:
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- criteria: (int, int, float): Type of criteria, max iterations, min error
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- calib_dir: string: directory of camera folders with checkerboard images
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- video: bool: True if video, False if images
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- extension: string: jpg, mpa, etc
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- corners_nb: (int, int): number of internal corners in the checkerboard (h, w)
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- square_size: (int) or (int, int): square or rectangle size in mm (h,w)
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- frame_for origin: int: checkerboard placed at world origin at frame N
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- vid_snapshot_every_N_frames: int: if video, calibrate on each N frame
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OUTPUTS:
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- ret: residual reprojection error in _px_: list of floats
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- C: camera name: list of strings
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- S: image size: list of list of floats
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- D: distorsion: list of arrays of floats
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- K: intrinsic parameters: list of 3x3 arrays of floats
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- R: extrinsic rotation: list of arrays of floats (Rodrigues)
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- T: extrinsic translation: list of arrays of floats
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'''
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calib_dir = args.get('calib_dir')
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cam_listdirs_names = next(os.walk(calib_dir))[1]
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video = True if args.get('video')==True or args.get('video')=='True' else False
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extension = args.get('extension')
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corners_nb = args.get('corners_nb')
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square_size = args.get('square_size')
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square_size = square_size*2 if len(square_size)==1 else square_size
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frame_for_origin = 0 if args.get('frame_for_origin')==None else args.get('frame_for_origin')
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if video:
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vid_snapshot_every_N_frames = args.get('vid_snapshot_every_N_frames')
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show = args.get('show_corner_detection')
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# Prepare object points
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objp = np.zeros((corners_nb[0]*corners_nb[1],3), np.float32)
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objp[:,:2] = np.mgrid[0:corners_nb[0],0:corners_nb[1]].T.reshape(-1,2)
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objp[:,0] = objp[:,0]*square_size[0]
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objp[:,1] = objp[:,1]*square_size[1]
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objpoints = [] # 3d points in world space
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imgpoints = [] # 2d points in image plane
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ret, C, S, D, K, R, T = [], [], [], [], [], [], []
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for cam in cam_listdirs_names:
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# Find corners in vid
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if video:
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video = glob.glob(os.path.join(calib_dir, cam, '*.'+ extension))[0]
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cap = cv2.VideoCapture(video)
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ret_vid, img = cap.read()
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while ret_vid:
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count = int(round(cap.get(1)))
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ret_vid, img_vid = cap.read()
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if count % vid_snapshot_every_N_frames == 0:
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img = img_vid
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imgp = findCorners(img, corners_nb, criteria, show)
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if isinstance(imgp, np.ndarray):
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objpoints.append(objp)
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imgpoints.append(imgp)
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cap.release()
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# Find corners in images
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else:
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images = glob.glob(os.path.join(calib_dir, cam, '*.'+ extension))
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for image_f in images:
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img = cv2.imread(image_f)
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imgp = findCorners(img, corners_nb, criteria, show)
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if isinstance(imgp, np.ndarray):
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objpoints.append(objp)
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imgpoints.append(imgp)
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# Calibration
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r, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, img.shape[1::-1],
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None, None, flags=cv2.CALIB_FIX_K3)
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h, w = img.shape[:-1]
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ret.append(r)
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C.append(cam)
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S.append([w, h])
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D.append(dist[0])
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K.append(mtx)
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R.append(rvecs[frame_for_origin].squeeze())
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T.append(tvecs[frame_for_origin].squeeze())
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# Object view to camera view
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RT = [rotate_cam(r, t, ang_x=np.pi, ang_y=0, ang_z=0) for r, t in zip(R, T)]
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R = [rt[0] for rt in RT]
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T = [rt[1] for rt in RT]
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R = [np.array(cv2.Rodrigues(r)[0]).flatten() for r in R]
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T = np.array(T)/1000
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return ret, C, S, D, K, R, T
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def toml_write(calib_path, C, S, D, K, R, T):
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'''
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Writes calibration parameters to a .toml file
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INPUTS:
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- calib_path: path to the output calibration file: string
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- C: camera name: list of strings
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- S: image size: list of list of floats
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- D: distorsion: list of arrays of floats
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- K: intrinsic parameters: list of 3x3 arrays of floats
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- R: extrinsic rotation: list of arrays of floats (Rodrigues)
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- T: extrinsic translation: list of arrays of floats
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OUTPUTS:
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- a .toml file cameras calibrations
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'''
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with open(os.path.join(calib_path), 'w+') as cal_f:
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for c in range(len(C)):
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cam=f'[cam_{c+1}]\n'
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name = f'name = "{C[c]}"\n'
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size = f'size = [ {S[c][0]}, {S[c][1]},]\n'
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mat = f'matrix = [ [ {K[c][0,0]}, 0.0, {K[c][0,2]},], [ 0.0, {K[c][1,1]}, {K[c][1,2]},], [ 0.0, 0.0, 1.0,],]\n'
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dist = f'distortions = [ {D[c][0]}, {D[c][1]}, {D[c][2]}, {D[c][3]},]\n'
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rot = f'rotation = [ {R[c][0]}, {R[c][1]}, {R[c][2]},]\n'
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tran = f'translation = [ {T[c][0]}, {T[c][1]}, {T[c][2]},]\n'
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fish = f'fisheye = false\n\n'
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cal_f.write(cam + name + size + mat + dist + rot + tran + fish)
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meta = '[metadata]\nadjusted = false\nerror = 0.0\n'
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cal_f.write(meta)
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def recap_calibrate(ret, calib_path):
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'''
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Print a log message giving filtering parameters.
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OUTPUT:
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- Message in console
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'''
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calib = toml.load(calib_path)
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ret_m, ret_px = [], []
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for c, cam in enumerate(calib.keys()):
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if cam != 'metadata':
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fm = calib[cam]['matrix'][0][0]
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Dm = euclidean_distance(calib[cam]['translation'], [0,0,0])
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ret_px.append( np.around(ret[c], decimals=3) )
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ret_m.append( np.around(ret[c]*1000 * Dm / fm, decimals=3) )
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print(f'--> Residual (RMS) calibration errors for each camera are respectively {ret_px} px, which corresponds to {ret_m} mm.')
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print(f'Calibration file is stored at {calib_path}.')
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def calibrate_cams_func(**args):
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'''
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Calibration from a checkerboard.
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Stores it in a .toml file
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Prints recap.
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Usage:
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calib_from_checkerboard -d "calib_path" -v False -e jpg -n 6 9 -s 1000
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OR calib_from_checkerboard -d "calib_path" -v True -e mp4 -n 6 9 -s 1000 1000 -O 0 -f 50 -o Test.toml
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OR import calib_from_checkerboard; calib_from_checkerboard.calibrate_cams_func(calib_dir=r"calib_path",
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video=False, extension="jpg", corners_nb=(6,9), square_size=[1000])
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'''
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calib_dir = args.get('calib_dir')
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output_file = 'Calib.toml' if args.get('output_file')==None else args.get('output_file')
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calib_path = os.path.join(calib_dir, output_file)
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# Calibrate
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criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001) # stop refining after 30 iterations or if error less than 0.001px
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ret, C, S, D, K, R, T = calib_checkerboard(criteria, **args)
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# Write calibration file
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toml_write(calib_path, C, S, D, K, R, T)
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# Recap message
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recap_calibrate(ret, calib_path)
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if __name__ == '__main__':
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parser = argparse.ArgumentParser()
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parser.add_argument('-d', '--calib_dir', required = True, help='Directory of checkerboard images or videos (one folder per camera)')
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parser.add_argument('-v', '--video', required = True, help='True if calibrate from videos, False if calibrate from images')
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parser.add_argument('-e', '--extension', required=True, help='Video or image files extension (jpg, png, mp4, etc)')
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parser.add_argument('-n', '--corners_nb', nargs=2, type=int, required=True, help='Number of (internal) square corners in the checkerboard: h,w')
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parser.add_argument('-S', '--square_size', nargs='*', type=int, required=True, help='Square or rectangle size in mm (int or int int)')
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parser.add_argument('-O', '--frame_for_origin', required=False, type=int, default=0, help='Checkerboard placed at world origin at frame N (-1 if last frame)')
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parser.add_argument('-f', '--vid_snapshot_every_N_frames', type=int, required=False, help='Calibrate on each N frame of the video (if applicable)')
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parser.add_argument('-s', '--show_corner_detection', type=int, required=False, default=0, help='Display corners detection overlayed on image')
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parser.add_argument('-o', '--output_file', required=False, default="Calib.toml", help='Output calibration file name')
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args = vars(parser.parse_args())
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calibrate_cams_func(**args)
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