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#!/usr/bin/env python
'''
Plot camera calibration extrinsics.
usage:
camera_calibration_show_extrinsics.py [--calibration <input path>] [--cam_width] [--cam_height] [--scale_focal] [--patternCentric ]
default values:
--calibration : left_intrinsics.yml
--cam_width : 0.064/2
--cam_height : 0.048/2
--scale_focal : 40
--patternCentric : True
'''
# Python 2/3 compatibility
from __future__ import print_function
import numpy as np
import cv2 as cv
from numpy import linspace
def inverse_homogeneoux_matrix(M):
R = M[0:3, 0:3]
T = M[0:3, 3]
M_inv = np.identity(4)
M_inv[0:3, 0:3] = R.T
M_inv[0:3, 3] = -(R.T).dot(T)
return M_inv
def transform_to_matplotlib_frame(cMo, X, inverse=False):
M = np.identity(4)
M[1,1] = 0
M[1,2] = 1
M[2,1] = -1
M[2,2] = 0
if inverse:
return M.dot(inverse_homogeneoux_matrix(cMo).dot(X))
else:
return M.dot(cMo.dot(X))
def create_camera_model(camera_matrix, width, height, scale_focal, draw_frame_axis=False):
fx = camera_matrix[0,0]
fy = camera_matrix[1,1]
focal = 2 / (fx + fy)
f_scale = scale_focal * focal
# draw image plane
X_img_plane = np.ones((4,5))
X_img_plane[0:3,0] = [-width, height, f_scale]
X_img_plane[0:3,1] = [width, height, f_scale]
X_img_plane[0:3,2] = [width, -height, f_scale]
X_img_plane[0:3,3] = [-width, -height, f_scale]
X_img_plane[0:3,4] = [-width, height, f_scale]
# draw triangle above the image plane
X_triangle = np.ones((4,3))
X_triangle[0:3,0] = [-width, -height, f_scale]
X_triangle[0:3,1] = [0, -2*height, f_scale]
X_triangle[0:3,2] = [width, -height, f_scale]
# draw camera
X_center1 = np.ones((4,2))
X_center1[0:3,0] = [0, 0, 0]
X_center1[0:3,1] = [-width, height, f_scale]
X_center2 = np.ones((4,2))
X_center2[0:3,0] = [0, 0, 0]
X_center2[0:3,1] = [width, height, f_scale]
X_center3 = np.ones((4,2))
X_center3[0:3,0] = [0, 0, 0]
X_center3[0:3,1] = [width, -height, f_scale]
X_center4 = np.ones((4,2))
X_center4[0:3,0] = [0, 0, 0]
X_center4[0:3,1] = [-width, -height, f_scale]
# draw camera frame axis
X_frame1 = np.ones((4,2))
X_frame1[0:3,0] = [0, 0, 0]
X_frame1[0:3,1] = [f_scale/2, 0, 0]
X_frame2 = np.ones((4,2))
X_frame2[0:3,0] = [0, 0, 0]
X_frame2[0:3,1] = [0, f_scale/2, 0]
X_frame3 = np.ones((4,2))
X_frame3[0:3,0] = [0, 0, 0]
X_frame3[0:3,1] = [0, 0, f_scale/2]
if draw_frame_axis:
return [X_img_plane, X_triangle, X_center1, X_center2, X_center3, X_center4, X_frame1, X_frame2, X_frame3]
else:
return [X_img_plane, X_triangle, X_center1, X_center2, X_center3, X_center4]
def create_board_model(extrinsics, board_width, board_height, square_size, draw_frame_axis=False):
width = board_width*square_size
height = board_height*square_size
# draw calibration board
X_board = np.ones((4,5))
#X_board_cam = np.ones((extrinsics.shape[0],4,5))
X_board[0:3,0] = [0,0,0]
X_board[0:3,1] = [width,0,0]
X_board[0:3,2] = [width,height,0]
X_board[0:3,3] = [0,height,0]
X_board[0:3,4] = [0,0,0]
# draw board frame axis
X_frame1 = np.ones((4,2))
X_frame1[0:3,0] = [0, 0, 0]
X_frame1[0:3,1] = [height/2, 0, 0]
X_frame2 = np.ones((4,2))
X_frame2[0:3,0] = [0, 0, 0]
X_frame2[0:3,1] = [0, height/2, 0]
X_frame3 = np.ones((4,2))
X_frame3[0:3,0] = [0, 0, 0]
X_frame3[0:3,1] = [0, 0, height/2]
if draw_frame_axis:
return [X_board, X_frame1, X_frame2, X_frame3]
else:
return [X_board]
def draw_camera_boards(ax, camera_matrix, cam_width, cam_height, scale_focal,
extrinsics, board_width, board_height, square_size,
patternCentric):
from matplotlib import cm
min_values = np.zeros((3,1))
min_values = np.inf
max_values = np.zeros((3,1))
max_values = -np.inf
if patternCentric:
X_moving = create_camera_model(camera_matrix, cam_width, cam_height, scale_focal)
X_static = create_board_model(extrinsics, board_width, board_height, square_size)
else:
X_static = create_camera_model(camera_matrix, cam_width, cam_height, scale_focal, True)
X_moving = create_board_model(extrinsics, board_width, board_height, square_size)
cm_subsection = linspace(0.0, 1.0, extrinsics.shape[0])
colors = [ cm.jet(x) for x in cm_subsection ]
for i in range(len(X_static)):
X = np.zeros(X_static[i].shape)
for j in range(X_static[i].shape[1]):
X[:,j] = transform_to_matplotlib_frame(np.eye(4), X_static[i][:,j])
ax.plot3D(X[0,:], X[1,:], X[2,:], color='r')
min_values = np.minimum(min_values, X[0:3,:].min(1))
max_values = np.maximum(max_values, X[0:3,:].max(1))
for idx in range(extrinsics.shape[0]):
R, _ = cv.Rodrigues(extrinsics[idx,0:3])
cMo = np.eye(4,4)
cMo[0:3,0:3] = R
cMo[0:3,3] = extrinsics[idx,3:6]
for i in range(len(X_moving)):
X = np.zeros(X_moving[i].shape)
for j in range(X_moving[i].shape[1]):
X[0:4,j] = transform_to_matplotlib_frame(cMo, X_moving[i][0:4,j], patternCentric)
ax.plot3D(X[0,:], X[1,:], X[2,:], color=colors[idx])
min_values = np.minimum(min_values, X[0:3,:].min(1))
max_values = np.maximum(max_values, X[0:3,:].max(1))
return min_values, max_values
def main():
import argparse
parser = argparse.ArgumentParser(description='Plot camera calibration extrinsics.',
formatter_class=argparse.ArgumentDefaultsHelpFormatter)
parser.add_argument('--calibration', type=str, default='left_intrinsics.yml',
help='YAML camera calibration file.')
parser.add_argument('--cam_width', type=float, default=0.064/2,
help='Width/2 of the displayed camera.')
parser.add_argument('--cam_height', type=float, default=0.048/2,
help='Height/2 of the displayed camera.')
parser.add_argument('--scale_focal', type=float, default=40,
help='Value to scale the focal length.')
parser.add_argument('--patternCentric', action='store_true',
help='The calibration board is static and the camera is moving.')
args = parser.parse_args()
fs = cv.FileStorage(cv.samples.findFile(args.calibration), cv.FILE_STORAGE_READ)
board_width = int(fs.getNode('board_width').real())
board_height = int(fs.getNode('board_height').real())
square_size = fs.getNode('square_size').real()
camera_matrix = fs.getNode('camera_matrix').mat()
extrinsics = fs.getNode('extrinsic_parameters').mat()
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D # pylint: disable=unused-variable
fig = plt.figure()
ax = fig.gca(projection='3d')
ax.set_aspect("auto")
cam_width = args.cam_width
cam_height = args.cam_height
scale_focal = args.scale_focal
min_values, max_values = draw_camera_boards(ax, camera_matrix, cam_width, cam_height,
scale_focal, extrinsics, board_width,
board_height, square_size, args.patternCentric)
X_min = min_values[0]
X_max = max_values[0]
Y_min = min_values[1]
Y_max = max_values[1]
Z_min = min_values[2]
Z_max = max_values[2]
max_range = np.array([X_max-X_min, Y_max-Y_min, Z_max-Z_min]).max() / 2.0
mid_x = (X_max+X_min) * 0.5
mid_y = (Y_max+Y_min) * 0.5
mid_z = (Z_max+Z_min) * 0.5
ax.set_xlim(mid_x - max_range, mid_x + max_range)
ax.set_ylim(mid_y - max_range, mid_y + max_range)
ax.set_zlim(mid_z - max_range, mid_z + max_range)
ax.set_xlabel('x')
ax.set_ylabel('z')
ax.set_zlabel('-y')
ax.set_title('Extrinsic Parameters Visualization')
plt.show()
print('Done')
if __name__ == '__main__':
print(__doc__)
main()
cv.destroyAllWindows()
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