I am following this tutorial (one of several): http://wiki.ros.org/camera_calibration Everything seems to be going swell until ubuntu crashes. This is making quite a bit of progress:

$ rosrun camera_calibration cameracalibrator.py --size 8x6 --square 0.25 image:=/raspicam_node/image camera:=/raspicam_node --no-service-check

(display:23906): dbind-WARNING **: 00:01:53.072: AT-SPI: Error retrieving accessibility bus address: org.freedesktop.DBus.Error.ServiceUnknown: The name org.a11y.Bus was not provided by any .service files
*** Added sample 1, p_x = 0.879, p_y = 0.535, p_size = 0.371, skew = 0.109
*** Added sample 2, p_x = 0.613, p_y = 0.650, p_size = 0.358, skew = 0.010
*** Added sample 3, p_x = 0.690, p_y = 0.413, p_size = 0.362, skew = 0.005
*** Added sample 4, p_x = 0.758, p_y = 0.207, p_size = 0.367, skew = 0.038
*** Added sample 5, p_x = 0.472, p_y = 0.771, p_size = 0.349, skew = 0.091
*** Added sample 6, p_x = 0.335, p_y = 0.733, p_size = 0.347, skew = 0.055
*** Added sample 7, p_x = 0.341, p_y = 0.462, p_size = 0.356, skew = 0.053
*** Added sample 8, p_x = 0.256, p_y = 0.479, p_size = 0.441, skew = 0.099
*** Added sample 9, p_x = 0.105, p_y = 0.538, p_size = 0.421, skew = 0.059
*** Added sample 10, p_x = 0.225, p_y = 0.086, p_size = 0.401, skew = 0.051
*** Added sample 11, p_x = 0.414, p_y = 0.099, p_size = 0.404, skew = 0.003
*** Added sample 12, p_x = 0.435, p_y = 0.279, p_size = 0.401, skew = 0.001
*** Added sample 13, p_x = 0.499, p_y = 0.386, p_size = 0.393, skew = 0.023
*** Added sample 14, p_x = 0.460, p_y = 0.518, p_size = 0.437, skew = 0.034
*** Added sample 15, p_x = 0.437, p_y = 0.618, p_size = 0.300, skew = 0.017
*** Added sample 16, p_x = 0.657, p_y = 0.620, p_size = 0.385, skew = 0.114
*** Added sample 17, p_x = 0.891, p_y = 0.697, p_size = 0.361, skew = 0.010
*** Added sample 18, p_x = 0.800, p_y = 0.309, p_size = 0.341, skew = 0.095
*** Added sample 19, p_x = 0.757, p_y = 0.107, p_size = 0.334, skew = 0.162
*** Added sample 20, p_x = 0.894, p_y = 0.137, p_size = 0.323, skew = 0.234
*** Added sample 21, p_x = 0.430, p_y = 0.246, p_size = 0.319, skew = 0.142
*** Added sample 22, p_x = 0.515, p_y = 0.468, p_size = 0.290, skew = 0.020

This has happened on several attempts. Any idea what might be the problem?

Thanks!