Presentation & Display: The Challenge of Next-Generation
By Will Craig
For her presentation at a private liberal arts college, a presenter confidently pulled out her laptop and set it on the table. Grabbing the handy VGA cable on the podium, she pulled it across to the table and pushed it against the back of her computer, but it didn’t feel quite right. Examining the back of her laptop, she discovered that her new laptop did not have a familiar VGA output after all; it had a DVI connector. Tech folks and staffers ran here and there, trying to find an adaptor. In the end, the presentation began 15 minutes late.
At a city council meeting, a civil engineer plugged his laptop into the city council chamber’s presentation system. His computer image appeared on all of the council and audience monitors, but not on the 17-inch annotation monitor built into the podium. Alas, the monitor could not handle the wide-aspect image from his laptop.
An architect designed a videoconferencing room with the instructor standing at a podium in the center of the room, directly in front of two rear projection screens. Now, the instructor is blinded by one or the other of the projectors, has no nearby whiteboard space on which to work, and the camera in the back of the room cannot pick up any detail of the instructor’s face because of the brightly illuminated background. Because all the directional lights face the audience, there are only about 15 foot-candles of light on the instructor’s face (when the projectors aren’t blinding him), so the camera in the back of the room d'es a poor job of resolving facial detail for the distance education broadcast. How unfortunate.
These three examples, all true stories, highlight some of the greatest challenges in working with this latest generation of presentation and display systems. The same trends that are leading to the next generation of systems are creating hurdles to be overcome in current product usage. So, let’s look at the trends and how they will impact (and be affected by) current technologies, then let’s look ahead to the next generation of presentation and display, and what you will need to know to get there.
Trend 1: DVI and HDMI
The DVI (Digital Visual Interface) standard was developed by the Digital Display Working Group to replace the analog VGA standard for computer graphics. The DVI standard supports bi-directional communication between the source and display device to enable them to agree upon an optimized output signal. This feature, designed for ease of use during setup, makes integration more complex when dealing with a classroom environment with multiple display devices. The five-meter maximum range of DVI also poses a challenge: Extenders are available, but since nearly every installed display device is more than 15 feet from the source, it’s clearly not integration-friendly.
DVI is seen on two connectors – DVI-I and DVI-D. The DVI-I has pins for both DVI and analog VGA. With a suitable passive breakout adaptor, you can connect a VGA display to a DVI-I equipped source. The DVI-D connector is digital-only; it will only connect to a DVI display, unless you use a DVI-to-VGA converter/scaler.
HDMI (high definition multimedia interface), becoming more important in the integration world, is essentially DVI in an even more user-friendly format, with the addition of multi-channel audio. With a form factor similar to but slightly larger than a USB connector, HDMI is dominating the high-def consumer market.
Trend 2: Widescreen
Simply put, widescreen is taking over. If you need proof, go down to your local electronics retailer and compare the number of widescreen laptops for sale versus conventional 4:3 aspect models. Then compare the number of widescreen projection televisions versus 4:3 aspect models. The computer formats and resolutions that have ruled with an iron fist for the past 10-plus years are disappearing rapidly.
Still, not all widescreen is the same. Even within one resolution “standard,” WXGA, there are multiple native resolutions (1365x768 for large monitors and projectors, 1280x768 for smaller monitors). Then there’s 1920x1080, 2560x1600, 1280x720, 1440x900, and more. And the aspect ratios of widescreen displays aren’t consistently 16:9; 15:9 is common, and you’ll find 16:10 out there, too.
Practical considerations for widescreen begin with the layout of the room. Wide aspect projection screens mean less room in the front for whiteboards, and more encroachment on where the instructor would stand. The projector typically needs to be positioned much farther back than a conventional 4:3 projector, since the image is significantly wider, and a longer throw distance is generally required. Where projector location is dictated by ceiling soffits or rear projection room dimensions, this can be troublesome.
Using wide aspect monitors means that the images are less tall than a comparably sized 4:3 display, so the diagonal monitor size must be larger in order to provide an equivalent-sized image. For example, a 50-inch 4:3 projection monitor has an image height of 30 inches. A 50-inch diagonal 16:9 projection monitor has an image height of only 24.5 inches. You would have to upgrade to the 60-inch 16:9 monitor in order to get back to a 29.4-inch image height. Larger monitor sizes for equivalent viewing considerations mean a larger footprint (new widescreen monitors may not fit on old stands or carts) and higher costs (60-inch 16:9 models cost $500 to $1,000 more than 50-inch models).
Finally, widescreen resolutions are not compatible with some legacy equipment – perhaps those 17- and 19-inch SXGA monitors you just bought with year-end money. When considering any display purchase, the question “How d'es it handle widescreen?” must become your mantra. If you want to verify that your sales rep is telling the truth, the Extron VTG-300 and VTG-400 test signal generators make product testing (and lie detecting) easy, and even fun.
Trend 3: Projectors Everywhere
A projector in every classroom is a condition no longer exclusively found in higher education. K-12 districts across the country are installing thousands of projectors at every level. And, colleges and universities are now relying on projection, front and rear, to enhance instruction in all fields of study.
Unfortunately, room designers have often failed to solve the problems that must be addressed when using projection technology in an instructional space:
- Too much (any) ambient light on the projection screen
- Inadequate lighting of instructor and whiteboards
- Imbalance of whiteboard space/access and the projection screen
- Inadequate sizing of screen and sightlines from audience
- Instructor “wander zone” interfering with projector light field
- Distance education/IP cameras pointed toward screens
- Projector fan noise
When these problems are not solved, a projector can actually detract from the learning experience. Rear projection, when properly implemented, can solve many of these problems, but the cost in equipment and square footage is often prohibitive.
Yet, if implementing front projection has so many potential (and sometimes unavoidable) pitfalls, why do smart people keep doing it? The reason is that the image is so big. Trying to show an extremely detailed computer image to people sitting 25 feet away using a 42-inch plasma screen (or even a 60-inch model) is insufficient. People need to see an image that is of sufficient size to resolve the detail that is presented, over the distance across which it is viewed. It’s essentially a three-variable equation, with distance, size, and detail affecting each other to produce the optimal viewing solution.
Until rear projection monitors (or direct-view flat panels) are large enough to provide equivalent-sized images to projectors, there will still be projectors hanging in classrooms – faults and all.
Seeking Perfection
Industry marketers are always pitching the “Next Best Thing.” But how do we know whether a new product is next generation or simply next-incremental-improvement? Incremental steps are necessary and beneficial, but the term “next generation” should be something that moves us toward something. What is the ultimate classroom display system? Here are four criteria that would need to be met:
- Large enough for everyone to see comfortably
- High-enough contrast for images to look natural in all lighting conditions
- Flexible in accommodating various resolutions and aspect ratios
- Form factor that d'es not interfere with classroom activities
Current Technologies
Love them or hate them, there is little available right now in the area of projectors to suggest “next generation.” In terms of meeting the criteria of the ultimate classroom display system, front projectors do well in terms of image size. The main area of weakness for projectors is in image contrast (front projection), where the lighting in the front of the room needs to be carefully controlled to avoid the image being washed out. Projectors vary by manufacturer and model in terms of how they handle various resolutions and aspect ratios. As of press time, very few 3000-plus ANSI lumen brightness, affordable (sub-$20,000), and native 16:9 projectors are available. And projectors dictate to a large extent the layout and design of a classroom: Once in place, the projector(s) and screen(s) aren’t likely to be moved, making reconfiguration of the classroom difficult to achieve.
Small (sub-20 lb.) projectors are continuing to get brighter: The Christie LX50 and Sanyo PLC-XP56 are prime examples. Ultimately, it’s not the brightness of the projector that matters to the end user, but rather the amount of light per square inch of screen. To get an image on a 150-inch diagonal screen that compares in perceived brightness to a 2500-ANSI lumen projector shining on a 100-inch diagonal screen, the projector would need to be more than twice as bright. So while a 5000-ANSI lumen projector might be uncomfortably bright on a 70-inch screen, it will work fine with bigger screens in larger rooms.
Monitors are seeing changes and growth, both as flat panels are released in larger sizes and lower price points, and as HDTV continues to drive development of large-screen projection monitors. While monitors do well as compared with front projection in terms of image contrast, they continue to fall short in terms of image size. And, monitors currently are moving faster than projectors toward HDMI as the sole input, making integration with existing analog systems more complex.
The Next Generation
What are the products we will be putting into classrooms in the next three to five years? Some of them may look like…
1.) Really Big Monitors. For a time, NEC offered the WT600-DS84 with an 84-inch diagonal image in a 16:9 aspect ratio. While the specifications stated that it would handle “up to 1920x1080 (1080i),” this single-chip DMD device had a native resolution of 1024x576. Oh, and the list price was $19,995. As a first-generation/next-generation product, though, it met the four criteria, at least for small-to-midsize classrooms. It was large, not greatly affected by ambient lighting, and it handled a wide variety of input signals and resolutions (VGA and DVI input connectors, and handled HDTV), and the form factor was reasonably compact – only 22.5 inches deep. Hopefully, more manufacturers will look at the potential for this type of product, both in classrooms, as well as in the home. Watch for prices to drop as second- and third-generation products emerge.
2.) Pretty Big Monitors. Terry Wirkus, Distance Education manager at the University of Wisconsin-La Crosse, reports that he is very satisfied with several Samsung 50-inch DLP rear projection monitors that have been used in his classrooms for a variety of applications, including computer presentations. With 60-inch monitors currently selling for $2,500 to $3,500, they represent an affordable and viable solution for smaller rooms, or where there are opportunities for placement of additional monitors toward the rear of larger/longer rooms.
Monitors in this size and price category come in at least three varieties appropriate for classroom use: LCD, DLP, and D-ILA. Many video purists insist that CRT and/or DLP are superior for video due to higher black levels and greater color contrast. However, it’s important to know that a small percentage of DLP viewers can be bothered by a phenomenon known as “rainbow artifacts,” wherein the viewer sees a blur of color around the monitor (this is especially noticeable via peripheral vision). Newer, higher-speed DLP devices have reduced this problem, but some people remain sensitive to it.
One should also keep in mind that computer-centric users may prefer LCD, pointing out the sharper pixel lines. If you want to compare the technologies side by side, I recommend that you take a field trip to your local big-box electronics retailer. Keep in mind that the settings made to each display in the store (by the salespeople or by inquisitive customers) can make any display look better or worse than another. The truth of the matter is, with a little adjusting, they all can look pretty good.
3.) Next-Generation Projectors. While not really new, I contend that the NEC WT-610 is a second-generation/next-generation product. The projector’s ability to throw a large image from a short distance allows a user to build (or commission) his own inexpensive rear-projection kiosks. Front projection works as well, solving most of the light path problems of a typical front-projection installation: The projector can be mounted just off the front wall of the room, above the screen, if necessary. While the brightness rating has increased from 1500 ANSI (WT-600) to 2000 ANSI lumens (WT-610), potential buyers should know that it’s still not really bright enough for larger screens (100-inches-plus), depending on the ambient room lighting. For rear projection applications, though, this should do fine.
Another first-generation/next-generation projector is the Sanyo PLV-WF10. It offers WXGA (1365x768) native resolution with 4000 ANSI lumens of brightness. A few cautions, however, when considering purchase of this product: The noise rating is 46dB, the PLV-WF10 weighs over 46 lbs, it uses two projection lamps (doubling lamp replacement cost), and the list price d'es not include a lens. What makes the PLV-WF10 exceptional is that it offers true WXGA resolution at high brightness something that the many 1280x720 home theater projectors out there fail to do.
Will Craig is a Multimedia Systems Design Consultant for Elert & Associates, a nation-wide multi-disciplinary technology consulting firm based in Stillwater, MN.