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216 8. Computer Vision in VR
Figure 8.24. A distinctive marker in the field of view of the camera provides a frame of
reference that is used to place virtual objects in the scene with a size and orientation
calculated to make them look like they are attached to the marker.
provides a neat library of functions for use in a C++/C application program
to overlay 3D virtual objects on the video from a digital camera in real time,
as illustrated in Figure 8.24. To be able to calculate a transformation that
will place the 3D virtual object correctly over the marker, the software has to
recognize the marker in the first place and then find its four corners. ...