[Studies in Computational Intelligence 481] Artur Babiarz, Robert Bieda, Karol Jędrasiak, Aleksander Nawrat (auth.), Aleksander Nawrat, Zygmunt Kuś (eds.) - Vision Based Systemsfor UAV Applications (2013, Sprin

154 A. Babiarz, R. Bieda, and K. Jaskot
Fig. 9. Position and size of playing field calibrated properly
The precision of measurements made by vision system is much improved when
compared to the previous system and seems to be sufficient to successfully attend
the RoboSoccer competition. Measurement errors are presented in the Table 2.
The great advantage of the vision system is that it never loses the position of any
object on playing field. Orientation axis is also always calculated properly, however
the measurement is usually a bit more distorted and there are some oscillations
visible. The only measurement that sometimes is done incorrectly is the
measurement of direction of orientation axis, fortunately it happens very rarely
and in future it should be easy to get rid of this problem by improving the shape of
color marker and by switching to higher resolution.
Table 2. Relative errors of measurements of a position and angle
Relative measurement error [%]
Radial Correction
Robot Ball
Enabled 0.5 0.6 1.5 0.4 0.5
Disabled 1.0 1.1 2.0 0.9 1.0
Precision of the measurements could possibly be further improved by introducing
compensation of cylindrical distortions of camera’s lens, this however is left
for further research. Switching to the higher resolution should also improve the
precision, for the objects will occupy more pixels on raster.