Wearable computers and augmented reality techniques can assist users by adapting their physical senses as well as augmenting them. Approximately 2 million Americans are affected by low vision, a set of conditions which can not be corrected with normal eyeglasses and severely affects the individual's sight. However, some of their needs may be addressed by remapping the visual input. To do this remapping, a camera is mounted on an opaque head-mounted display. The image is wirelessly transmitted to a remote computer, processed, and sent back to the head-mounted display. The process of completely controlling the user's visual field has been termed ``mediated reality'' [Mann, 1994] to distinguish it from the ``see-through'' effect generally associated with augmented reality. With off-the-shelf SGI hardware, the incoming video may be remapped arbitrarily in real time. Figure 13 shows how text can be magnified by applying a simple 2D `hyper-fisheye' coordinate transformation. This allows individual letters to be magnified so as to be recognizable while still providing the context cues of the surrounding imagery. Figure 14 shows how the same technique can be used to map around scotomas (``blind spots''). Until self-contained systems such as [Baker, 1994] can include the processing power necessary to perform this amount of computation, such systems can provide a general experimental platform for testing theories of low vision aids. If considerable wireless bandwidth is made available to the public, as per [Nagel and Lovette, 1995], then this system may become practical. Since only cameras, a HMD, and a transmitter/receiver pair are needed, the apparatus can be made lightweight from off-the-shelf components. Furthermore, this approach may improve battery life by using just enough power to transmit the video to the nearest repeater instead of trying to process the video locally.
Figure:
In order to help those with low vision, the visual field
is remapped through a ``hyper-fisheye.'' Note that while the letters
in the center of the screen are enlarged, enough of the rest of the
field is included to provide context.
Figure:
Visual remapping around a scotoma or ``blind-spot.'' Note the
desired distortion in the cobblestones as the image in the blind spot
is pushed to either side.
Note that the techniques from previous sections can also be used in such contexts. The wearable computer acts as a guide to physical spaces and also adapts for its user's abilities. For example, for a user with low vision, the location and visual tracking systems of the wearable computer may actively direct the user to objects that would be difficult to find or manipulate even with the remapped visual field.