Angles Of View
As the final year of this decade, century, and millennium begins, the future of the A/V industry has never looked brighter. That our customers, their markets and their institutions will continue to require information display systems from us is comfortingly certain. Although it will be the computer industry that will create that information, it will be our industry that will be presenting it. The techniques and the equipment available to assist us in that task are evolving at breathtaking rates which are unlikely to decelerate. Many of these new technologies will compel us to ask new questions; few will substantiate old answers. Exploring the more intriguing of these developments is the subject of this series' fifth volume. Among the first of these Issues for the Millennium, we discuss
New Years' ResolutionIn the context of visual displays, here are some of the questions that all of us at
Da-Lite Screen Company have been asking ourselves lately.
How bright are projectors going to get?
How much resolution will people be expecting (and expected) to look at?
What aspect ratio (or ratios) will projection screens have to accommodate?
What formula (or formulae) should be used to calculate the size and position of those screens?
What will be the new projection geometries and how will they affect viewing angles?
What screen surface (or surfaces) should be recommended?
At Da-Lite, we believe the answer to each of these questions is not only important, but new. This article will begin to suggest why.
Let's look first at projector output. Industry watcher and astute technology analyst, Gary Kayye (firstname.lastname@example.org) has written recently that by the end of 1999 he expects to see "3000 to 5000 ANSI lumens projectors all over the place." We agree; and it won't be too long into the 21st century when double those amounts will become equally ubiquitous.
Now, let's be clear: 10,000 ANSI lumens is a lot of light; more than enough, in fact, to illuminate adequately all but the very largest of screens in the very toughest of venues. Once upon a time (and for a very long time thereafter) brightness was the first and paramount consideration when it came to designing and specifying a visual display. Many, many other variables were subordinated to the brightness issue and properly so. But those days are finally over and, therefore, the first thing we should recognize is that brightness will not be an issue for the new millennium.
Conversely, resolution, barely a factor when projectors were in their dim, dark infancy, has grown into an issue whose importance has become inversely proportional to brightness and will soon completely supplant it.
As an issue, VGA (a meager 640 x 480 pixels) meant almost nothing. That modest beginning has been overturned several times and, although XGA (1024x768) is typical today, 1024 x 1368 isn't far off. What will the turn of the century reveal? 2000 x 1600. Count on it.
Now 3,200,000 pixels is a lot of pixels; more than enough, in fact, to fill even the very largest of screens. Of course, the overwhelming number of screens that it will fill won't be in large venues, they'll be in conference and training rooms, just like they are now. And for those more modest screens resolution of that density must be managed with the utmost care or the vast new number of trees may completely obscure the forest. Whether, you see, we need the resolution or not to effect our presentations, we're going to have it. Learning to control and manage resolution may possibly be the single largest issue affecting the visual displays of the future. Certainly it is from the vantage point of screens.
Next there's the question of aspect ratios. Scaling through the past, 4:3 has prevailed steadily until recently when "work station" (1280 x 1024) displays became projectable and projection screens with its 5:4 aspect ratio began to crop up here and there. To be sure, the effect of that addition has not been seismic but there is another aspect ratio lurking in the wings which will, all by itself, revolutionize everything. We refer, of course, to 16:9 which not only will stretch all of our projection geometries out of their current shape, but is likely to impose on us its own quite extraordinary resolution of 1920 x 1080 ( a prodigious total of 2,138, 400 pixels).
Few, if any, current projectors can actually display that resolution in that aspect ratio today. But they will; and when they do the repercussions on commercial displays will be so profound that all of their consequences aren't yet predictable. But here are at least some of them.
To manage that aspect ratio today most projectors simply "mask off" the top and bottom of their native 4:3 aspect ratio causing, effectively, the "3" part to be reduced to 2.25. Although that change makes the size of the image smaller, it has no effect on the throw distance required to cast that image size nor, really, on the bend or viewing angles that its light rays have to travel to reach the eyes of the audience.
When, however, the 16:9 aspect ratio is native to a projector, then what was once 4:3 will become 5.33:3 which will (must) produce images that are significantly wider (and hence larger). What lenses, with what focal lengths will be chosen is not altogether clear at the moment, but the consequent projection geometry, whatever its details, will definitely be a new issue for the next millennium.
To belabor this point just one step further, consider a screen that is 72 inches high. Its width today is almost certain to be 96. If it's a work station, that width is reduced to 90. If it becomes 16:9, however, the width increases 33%, to 128 inches and its area equally increases from 48 to 64 ft˛.
Brighter projectors, of course, will take care of the larger area. But notice that the bend angle issue nevertheless remains. Viewing angles to the edges of a 16:9 screen will inescapably be greater than they were for the original, 4:3 surface it replaces. How shall we size this new screen? Should we begin with its height and ensure that it be some fraction (ź?) of the distance to a Least Favored Viewer? Probably we should, though we will do well to keep in mind that taller ceiling heights are not likely to be prominent among the virtues of the next century's office architecture. Thus, audience layout and viewing geometries are also issues which will deserve our most careful and new attentions.
Lastly, we come to the issue of what screen surfaces are to be preferred for the displaying of all these forthcoming and wondrous developments. And on this subject, Da-Lite Screen Company is as clear as we are certain. Our overarching precept is that low gain screens are to be preferred to high gain screens whenever possible. There is nothing cryptic about this conclusion and its validity can be established in a few simple sentences. Projectors can create light. New Projectors can create a lot of light. Screens, even new ones, cannot create any light.
In front projection, this is simply yet another way of reenforcing the suitability of Matte White. (True, there are some subtleties here, but they are the subject of another article.) In rear projection, however, the news may be somewhat more startling.
It is our conviction that the first and best rear projection screen surface available today and completely suitable for the future is a Da-Lite Diffuser with a "gain" of only 1. To put it even more baldly, yes, we believe that diffused surface to be superior to all of the lenticulated, profiled screens which we sell.
Now our point here is not to announce that we're excising profiled screens from our product lines. We aren't, we shouldn't, and we won't. There will continue to be applications encountered by all of us wherein a profiled screen will represent the only viable solution. But, looking to the future, we think the number of those installations will diminish.
Once, the great advantage to profiled screens was their gain. Gains of 2, 3, 4 and even 5 were producible from profiled screens without having to pay a hideously expensive price in overall uniformity and viewing angle. But with the sort of lumens increasingly available to us, who needs all that gain anymore? As we have remarked elsewhere, excessive screen gains can actually make a display become too bright for comfort.
That's the negative reason why a 1-gain diffusion screen (DA-100 in Da-Lite's nomenclature) is a better idea. The positive reason is that it possesses unlimited resolution. No profiled screen can say that. All profiled screens, by definition, have a resolution limit that is directly dependent on the frequency of their lenticulations. As the resolution of displays increases, the periodic structure of even very fine pitch lenticulations will become a troublesome and possibly even destructive issue. In contrast, the diffuser poses no such risk.
Another way of thinking about this is to suggest that the life expectancy of any installed rear projection is quite likely to be two projectors and maybe three computers. What we know about two of those devices is that each will be brighter than its predecessor. What we guarantee about all five is that their resolutions will be higher. What we know about the screen is that it must compromise none. And, thus, for the moment, we hope the issue can be resolved.