Good article!
A few comments:
1) If the image is a simulation of an SV-3 why not make it a simulation
of an "occluding monocular with VGA resolution"? The rest of the article
only references monocular HMDs in general. The specific reference looks
out of place.
2) List the manufacturers of monocular HMDs in a side bar or endnote.
These articles are a valuable resource for most readers. A list of
manufacturers will allow them to check out what is on the market without
having to do an extensive web search.
3) While this is great testimonial for Monocular HMDs, a section on
drawbacks or challenges should be offered as well. Things like
durability, interconnection (signal and power cable issues), social
acceptance, collaborative or shared viewing and cost are all topics that
can be addressed. It is important to give both sides of the story.
4) There are two paragraphs devoted to the research on high and low
resolution. In practice, most purchase decisions come down to price.
As an example, application designers have reworked applications to
accommodate resolutions as low as QVGA, without giving up any
functionality, in order to meet their target cost for the deployed
hardware.
http://pd.pennnet.com/Articles/Article_Display.cfm?Section=Archives&Subs
ection=Display&ARTICLE_ID=54193&KEYWORD=comsonics
In industrial applications with a large installed base, the hardware
costs are recurring and must be kept as low as possible. The marginal
cost to deploy software to an additional user is next to $0 while the
marginal cost to deploy hardware to an additional user is the same as it
was to roll it out to the very first one.
-Tony
>
> Here is a draft of a short article I'm preparing for IEEE
> Pervasive Computing magazine. I would appreciate suggestions
> on how to improve it as it is intended for a technical
> audience who does not necessarily know about wearable displays.
>
> The image for Figure 1 is at
> http://www.cc.gatech.edu/~thad/overlay-sv3.jpg
>
> and the caption I'm suggesting is
>
> Figure 1: Simulation of the overlay effect of using a
> monocular opaque head-up display.
>
> I was thinking of putting in a figure that helps illustrate
> the power difference between PDAs and HUDs, but I think the
> analogy works well enough and my drawing skills are poor. Opinions?
>
> We could also put in an image of the SV-3 display being worn
> to go with Figure 1 if people think it would add something.
>
> Thad
>
> ------------
> The Enigmatic Display
>
> The monocular head-up display is the most distinctive
> component of many wearable computers. Yet this style of
> display is often misunderstood as to how and why it is used.
> This month I examine the most common questions on wearable
> displays and point to new research on their use.
>
> *Why use a head-worn display?*
>
> In many industries, workers have both hands occupied while
> requiring access to information. For example, a surgeon may
> perform an intricate microscopic procedure while watching a
> magnified view of his actions on a head-up display. An
> overlay of the patient's vital signs may provide the surgeon
> additional context during the procedure. Similarly, a network
> technician might use a head-up display so that he can monitor
> packet transmission while using his hands to physically
> reconfigure a router. In Europe, BMW recently showed an
> augmented reality (AR) system for automobile technicians; the
> head-up display was used to overlay 3D graphics on a BMW
> engine which guide the technician for each required step in
> the engine's service.
>
> Beyond industry, monocular head-up displays also show
> potential in consumer products. A growing number of
> individuals have adopted these displays as part of their
> normal life. For me, the display provides a quick way to
> access my calendar, refer to notes while teaching class,
> inconspicuously write notes on a conversation, or even read
> the next paragraph of an article while walking to my next
> appointment. I have even been known to use a head-up display
> to read in bed so as to avoid the fatigue of holding a book
> over my head for extended periods of time.
>
> *What does the display look like? What can you do with it?*
>
> Figure 1 shows a simulation of using the MicroOptical SV-3
> monocular display. The SV-3 is a color VGA display with
> 640x480 resolution and a 16 degree horizontal field of view
> (19 degree diagonal). In practice, the image from the
> computer seems to float in space, overlaid on the real world.
> Because of a trick of the human visual system, most users
> perceive that they "see through" the display even though it
> is opaque.
>
> A similar effect can be seen by holding your thumb a couple
> of inches in front of one eye while focusing on something in
> the distance with the other. The thumb is out of focus, of
> course, but you perceive both your thumb and the object in
> the distance, even if the object would at first seem to be
> obscured by your thumb. Closing first one eye and then the
> other demonstrates how different the images to each eye
> really are. Opaque head-up displays take advantage of this
> effect to create the illusion of overlay. In addition, they
> use optics (much like those of a microscope) so that both the
> display and the distant object are in focus simultaneously.
>
> Since many of these units can be driven from a standard VGA
> port, they are capable of displaying information just like a
> normal desktop computer. In general, monocular displays can
> be used by anyone with normal vision, corrected or
> uncorrected. Some displays clip on to eyeglasses or
> sunglasses if the user does not wear eyeglasses. Other
> displays are mounted to a form of headband and sit forward far
> enough from the forehead that the user can wear eyeglasses
> underneath.
>
> --------------------------------------------------
> TABLE/SIDEBAR
> Advantages of head-worn displays:
>
> Size/weight
> Speed of access
> Less vulnerability to damage
> Hand support unnecessary
> Less strain/fatigue for back, neck, and hands
> Adjustable focus
> Less power
> Virtual overlay on physical world
> Privacy
> Less interruptive
> Potential for large virtual image
> --------------------------------------------------
>
> *What are the advantages of a head-worn display?*
>
> Compared to the displays of a laptop or PDA, modern head-worn
> monocular displays have a distinct size and weight advantage.
> For example, the head of my display weighs 35 grams
> (slightly over an ounce). When I am not wearing my display,
> I store it in my shirt pocket. In today's world, most people
> assume that it is an earphone for a cellular phone or a MP3
> player. However, when I need it, I can still access the
> display very quickly.
>
> This speed of access is another significant advantage. PDA
> users must reach into their pocket or briefcase, uncase the
> PDA, boot it, pull out the stylus, and get to the right
> application. With a head-up display and a fast mounting
> system, the user can access their system in as little as 1/10
> of the time of a PDA user. Such accessibility allows
> frequent use of the display and wearable computer for quick
> reference and note-taking.
>
> Since a head worn display is small and mounted near the face,
> it is naturally more protected than a PDA or laptop screen.
> PDA screens are relatively large and vulnerable surfaces in a
> mobile environment. Since the PDA may be stored in a pocket,
> its screen can easily be subjected to large forces if the
> user sits on it or places a large object on his lap. Another
> problem with PDA-sized screens is that they must be supported
> by a hand. In fact, most PDA interfaces require the use of
> both hands (one for support and one for the stylus) and both
> eyes. If a PDA user attempts to use the interface when
> walking, much of his attention will be devoted to
> compensating for the mechanical shock of the movement. Thus,
> both the user's physical and attentional resources can be
> consumed by the PDA. On the other hand, a wearable with a
> head-up display demands much less of the user while mobile.
>
> A head-worn display can also provide much better ergonomics
> than a desktop, PDA, or laptop screen. Instead of requiring
> the user to sit in an upright position with hands, neck, and
> back in the proper location, the user of a head-worn display
> has much more freedom. I, for example, often lay on the sofa
> in my office to write my papers. Such freedom can be a
> release from occupational pain for sufferers of back, neck,
> and hand injuries. (One unfortunate side effect, though, is
> that visitors sometimes initially think I am sleeping when
> they enter my office for their appointment).
>
> Another ergonomic benefit of several of the modern head-worn
> displays is their adjustable focus. Frequent users of
> desktops and laptops are vulnerable to "computer vision
> syndrome" (CVS) due to the eye being forced to attempt to
> focus at a near distance for extended periods of time,
> Symptoms include headaches, loss of focus, burning/tired
> eyes, double vision, blurred vision, and neck and shoulder
> pains. Some optometrists even consider such computer use to
> increase the risk of myopia (near-sightedness) in children.
> According to Prio \cite{Priowebsite} and Bausch and Lomb
> \cite{Bauschwebsite}, makers of equipment for CVS, computer
> vision syndrome is due to the difference in the resting point
> of accommodation (RPA) and the distance users have to focus
> their eyes to read a computer screen. The RPA is the distance
> at which the eyes focus by default (around 76 cm or 30
> inches). With an adjustable focus screen, a head-worn
> display user can vary his focus from a near depth to the RPA
> to even an effective infinite depth depending on what
> provides the user with the most comfort.
>
> Head-worn displays also have an advantage over PDAs in the
> amount of power they require. In order to be useable, a PDA
> must be viewable from many different angles, even if the
> perceived image subtends the same amount of effective visual
> arc as a head-up display. However, a head-worn display is
> mounted so that its light is relatively focused into the eye.
> Thus, head-worn displays naturally require less power than a
> PDA screen. To illustrate the idea, the PDA might be thought
> of as a flashlight which casts its light over a wide area
> whereas the head-worn display might be thought of as a slide
> projector that tries to provide a brilliant image in a limited area.
>
> Head-worn displays offer some unique features over PDA and
> laptop screens. Since the display is worn close to the eye,
> spying on the user's screen without his knowledge is nearly
> impossible. Combined with appropriate sensing, head-worn
> screens can be used to create a real-time overlay of graphics
> on to the physical world. In addition, accelerometers or a
> magnetic compass can be used to create a virtual head-up
> display; as the user rotates his head, the image in the
> display pans through a virtual image rendered in a ring
> around the user's body \cite{billinghurst,macintyre}.
>
> Head worn displays can also be less socially obtrusive than
> many alternatives. For example, a cellular phone call can be
> announced discretely with its caller ID in the user's display
> instead of an insistent and uninformative mobile phone ring.
> As another example, instead of needing to look away from his
> interviewee to put pen to paper, a reporter can maintain eye
> contact while typing notes to his display. Such subtlety can
> help avoid derailing the discussion as the artifacts of the
> interviewer's notetaking (e.g. notepad, pencil, writing,
> etc.) are no longer visible.
>
> *If head-worn displays have so many advantages, why haven't
> they penetrated the market?* or *Why aren't they here yet?*
>
> While head-worn displays have a history going back to the
> earliest efforts in computer graphics, only recently have
> small, mobile computers and appropriate communications
> infrastructure been developed that would benefit from their
> use. Now that the concepts of SMS typing, game playing, and
> photography on cellular phones are becoming popular, there
> will be greater impetus to adapt head-worn displays to those
> markets. In addition, wide area wireless Internet access is
> beginning to become reliable, and the public will begin to
> embrace the idea that they do not have to be limited to their
> office to have access to full-scale computing support.
>
> However, microdisplay manufacturers still face difficult
> challenges. For example, the display's field of view must be
> balanced against the amount of visual area occluded by the
> display's support hardware. Cost, brightness, contrast,
> power, resolution, social obtrusiveness, and clarity are only
> some of the factors that manufacturers must consider. While
> the state of the art has limited manufacturers in these
> trade-offs in the past, recent studies have shown a beginning
> maturity in the field, both in hardware and experimental practices.
>
> In the Journal of Optometry and Vision Science, Sheedy and
> Bergstrom report that users performed very similarly on
> paragraph reading, letter counting, and word search tasks
> when using a monocular 800x600 resolution display (e-case by
> InViso) versus hard copy or a 15" flat panel display.
> \cite{Sheedy} In some cases, the monocular display actually
> outperformed the other display methods, but the results for
> these tests were not statistically significant. Similarly, a
> binocular display (e-shades by InViso) tested had slower or
> equal performance rates on the tasks when compared to the
> monocular display, hard copy, or the flat panel, but the
> results were not statistically significant. In previous
> experiments, older head-worn displays did not perform as well
> as desktop monitors or hard copy. In this study, the authors
> attribute the current favorable comparison to improved
> display resolution, partial instead of full immersion, and
> several other effects best described in the original paper.
>
> While Sheedy and Bergstrom's experiment shows the promise of
> the image quality of the newer wearable displays, Laramee and
> Ware have been exploring the effects of various backgrounds
> on task speeds when using a monocular display. In their
> paper "Rivalry and Interference with a Head Mounted Display,"
> Laramee and Ware experiment with both a see-through monocular
> display and an opaque monocular display. Users were required
> to scan through a table of items and prices and use a mouse
> to click on a specified price given a question such as "What
> is the price of lettuce?" While performing this task, the
> users either saw a bookshelf or a television playing a movie
> in the background. The authors found statistically
> significant evidence for both binocular rivalry (what one eye
> sees affects the other) and interference (the background in a
> see-through display can conflict with what the user is
> doing). However, the effects were not as strong as the
> authors expected, especially in the case with the static
> background. While there are many aspects that can be further
> explored (adjusting brightness, contrast, and transpareny
> levels; using higher resolution than the 450x266 IO Display
> Systems i-glasses in the experiment; exploring focus effects
> with the TV background; exploring other user tasks; etc.),
> this experiment shows a desire to examine more complex tasks
> with head-worn displays. More such experiments from the
> research community are needed to help display manufacturers
> and wearable software providers tune their products and
> overcome limitations to head-worn display use.
>
>
> URLs:
> http://www.prio.com/consumers/problem.shtml
> http://www.bausch.com/us/vision/products/magnifiers/cvs.jsp
>
> References:
>
> James Sheedy and Neil Bergstrom. "Performance and Comfort on
> Near-Eye Computer Displays." Optometry and Vision Science,
> 79(5), May 2002, pp. 306-312.
>
> Robert Laramee and Colin Ware. "Rivalry and Interference
> with a Head Mounted Display." ACM Trans. on Computer Human
> Interface (TOCHI), 9(3), September 2002, pp. 238-251.
>
> Mark Billinghurst and Thad Starner. "Wearable Devices: New
> Ways to Manage Information." IEEE Computer, 32(1), January
> 1999, pp. 57-64.
>
> <need appropriate MacIntyre/Feiner article>
>
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