Vision Augmentation using Spatial Defocusing via Focal Sweep Eyeglasses and High-Speed Projector
Vision Augmentation using Spatial Defocusing via Focal Sweep Eyeglasses and High-Speed Projector论文理解
The primary contributions of this paper are as follows:
• Introduce the IlluminatedFocus technique, an innovative com-putational display framework that achieves depth-independent
spatial defocusing of real-world appearances via focal sweep
eyeglasses and a high-speed projector.
• Construct a mathematical model to compute the blur range of
a user’s eye to establish a design guideline to determine effective
illumination timings and the range of the focal sweep.
• Propose a blending technique to diminish a conspicuous seam
between blurred and focused areas.
• Confirm the feasibility of the IlluminatedFocus technique by
implementing vision augmentation applications, such as visual
guidance and concealing undesired visual information.
The innovative aspects of this paper are:
In all the above-mentioned previous systems, blurred real-world
appearances are displayed on VST displays, such as HMDs and smart-phones. Because the blur effect can be implemented by a simple video signal processing, depth-independent, and spatially varying blur can be synthesized and displayed on VST displays. On the other hand, as discussed in Section 1, there is no simple solution to realize such a flexible focus control in any vision augmentation platforms including OST-AR and SAR. Because users see the real world directly in these systems, a blur needs to be controlled optically.
System
In this system, the ETL focal length is modulated periodically at 60 Hz, which is performed at higher than the critical fusion frequency (CFF), the observer does not perceive the modulation and the blink of the illumination.
Here, focal sweep refers to an optical technique that periodically modulates the optical power of an optical system (observer’s eyes in our case) such that every part of an observed real scene is focused once in each sweep. If part of the scene is illuminated by a synchronized illuminator only when it is in the focal range of the observer’s eyes, it appears focused. On the other hand, if another part is illuminated only when it is out of focus, it appears blurred.
The mathematical basis of this technique:
The angle of the marginal ray uo at the object can be computed by solving the following equation:
where
De, ue, d Ee, PE , and doE represent the diameter of the pupil, the angle of the ray at the eye, the distance between the ETL and the eye, the optical power of the ETL, and the distance between the object point and the ETL, respectively. Thus:
Finally, size of the blur circle on the image plane is computed by solving the following equation:
where ur, der, and Pe represent the angle of the ray at the image plane (i.e., retina), the distance between the lens of the eye and the retina, and the optical power of the lens of the eye, respectively. Substituting Equation 5 in Equation 6 gives the resultant size of the blur circle asfollows: