Mediated Reality: University of Toronto RWM Project
Of course, one cannot expect a head-tracking device to be provided in all possible environments, so head tracking is done by the reality mediator, using the VideoOrbits (see Resources 3) tracking algorithm. (The VideoOrbits package upon which RWM is based is freely available at http://wearcam.org/orbits/index.html.) The VideoOrbits head tracker does head tracking based on a visually observed environment, yet works without the need for high-level object recognition.
VideoOrbits builds upon the tradition of image processing (see Resources 4 and 5) combined with the Horn and Schunk equations (see Resources 6) and some new ideas in algebraic projective geometry and homometric imaging, using a spatiotonal model, p, that works in the neighborhood of the identity:
where øT = [Fx(xy, x, y, 1), Fy(xy, x, y, 1), F, 1], F(x,t) = f(q(x)) at time t, Fx(x,t) = (df/dq)(dq(x)/dx), at time t, and Ft(x,t) is the difference of adjacent frames. This “approximate model” is used in the innermost loop of a repetitive process, then related to the parameters of an exact projectivity and gain group of transformations, so that the true group structure is preserved throughout. In this way, virtual objects inserted into the “reality stream” of the person wearing the glasses, follow the orbit of this group of transformations, hence the name VideoOrbits.
A quantagraphic version of VideoOrbits is also based on the fact that the unknown nonlinearity of the camera, f, can be obtained from differently exposed images f(q) and f(kq), etc., and that these can be combined to estimate the actual quantity of light entering the imaging system:
where ci is the derivative of the recovered nonlinear response function of the camera, f, and A, b and c are the parameters of the true projective coordinate transformation of the light falling on the image sensor. This method allows the actual quantity of light entering the reality mediator to be determined. In this way, the reality mediator absorbs and truly quantifies the rays of light entering it. Moreover, light rays entering the eye due to the real and virtual objects are placed on an equal footing.
MR sets forth a new computational framework in which the visual interpretation of reality is finely customized to the needs of each individual wearer of the apparatus. The computer becomes very much like a prosthetic device or like prescription eyeglasses. Just as you would not want to wear undergarments or another person's mouth guard, you may not want to find yourself wearing another person's computer.
The traditional paradigm of one worldwide software vendor providing everyone with identical copies of an executable-only distribution no longer applies. Instead, complete reconfigurability is needed and each user will customize his or her own environment. Since many laypersons are not well-versed in operating system, kernel source code, a need will grow for system administrators and consultants.
In the future, software will be free and users will buy support. There will be little problem with software piracy, both because the software will be free and because a version of the software customized for one person will be of less use to someone with different needs. Because the computer will function as a true extension of the user's mind and body, it would not do the user well to ingest software owned by someone else. The computer will function much like a “second brain”, and in the true spirit of freedom of thought, it would be preferable that any commercial interests in the customization and contents of one's “second brain” be a work for hire (e.g., an interaction in which the end user owns the rights) rather than a software purchase. Thus, there will be an exponentially growing need for personal system administrators as new people enter the community of connected, collective, humanistic intelligence.
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