[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

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Fig. 10. Distorted (a) and undistorted (b) chessboard
Pressing the Calibration button is possible only after capturing specific amount
of samples containing the chessboard. It calls a function of camera calibration,
which straightens video stream, using determined calibration parameters. The
parameters are exploited
to create a map of distortion, which serves proper
straightening of the received video streams (fig. 10) the corners taken before, de-
termines the external and internal
Fig. 11. Combined video streams, in 2D (a) and 3D (b)
The second important library used in the creating of the program was OpenGL,
a graphic library well known by people dealing with computer games graphics.
The use of this library created a possibility to display acquired video streams in a
three-dimensional space, which in turn solved, to a large extent, the problem of
joining the streams captured by adjacent cameras. That problem is a result of the
fact, that each camera observes its surroundings from different angle, so the same
object captured by two adjacent cameras has different shape (Fig. 11). Elements of
the library created a possibility of placing an observer inside virtual hexagon-
shaped room, and displaying the image registered by the cameras on its walls.
This way the angle, at which cameras could see their surroundings, was also the
angle of view of the observer. OpenTK [10] library, which is an equivalent of
OpenGL library in C# language, was used to implement this mechanism.