Originally published in the June 1996 issue of:
Seeing the Architectural Problems in Projection System Design
By Barry McKinnon
The projected image is showing up everywhere, and more often than not these days, it's a video image you're seeing. Video projection is bound by constraints that are different than conventional optical systems such as slide and overhead projectors and that presents some design problems caused by the extensive experience with the "prior art" of optical projection, not so much by the system designers, but by the room designers. The technical side of optical projection involved the correct choice of lens, the correct lamp size, minimizing keystone, and a sharp eye for focusing and registering multi-slide image systems. The technical aspects of video projection involve many new factors: resolution, bandwidth, horizontal scan frequency, vertical sync frequency, peak white output versus ANSI Lumens, scan doubling, component video versus S-Video versus composite video, TFT-LCD versus DMD versus CRT, green lens vertical projection line offset angles, maximum keystone correction capability, lens selection and projection distance, plus no end of control and adjustment issues. That's quite a step up from the world of optical projection for the system designer.
By contrast, the projection system design issues that are of concern to the architectural or interior design people, the room designers, are quite limited: get the projection screen in the right location, get the projector in the right location, get the viewers in the right location, and finally, keep ambient light off of the projection screen. This information is supplied by the manufacturers of the projection equipment, or by the system designers and contractors working with the architects and interior designers to integrate the design. Why then is this part of the design equation so much more complicated to resolve? This question is often on the lips of many systems designers and contractors, and an insight into the viewpoint of the architects and interior designers may be useful, in the manner of "walking a mile in their shoes." An understanding of what the real objections are may help develop a creative solution that benefits all concerned by making the design process less stormy.
The first area of conflict comes from the relative viewpoints of the system designer and the room designer. For the system designer, a projection screen is the focal point of a visual presentation process, and has clear precedence over other elements of the room design in order that it may deliver the required measure of visual intelligibility to all the viewers. To the room designer, the screen is viewed as a necessary evil to support some specific aspect of the room's use, but because of the need to be located in a highly visible location, it becomes a large and intrusive design element that does not mesh with the visual impression being created in the room's architecture. If projection is an ongoing requirement rather than a temporary or occasional one, the screen surface becomes a permanent eyesore, with no option for color variation, or surface texture. It becomes the equivalent of an oil stain on the paper of a water color rendering, an annoying patch beyond the influence of visual design.
The screen can also interfere with the location of other critical elements, especially in education environments, where the screen will typically overlap the blackboard surface (the exception being lecture theatres with very tall front walls). The screen usually interferes with other items such as the preferred clock, paging speaker and blackboard lighting locations. In most of these applications the screen is electric and is out of sight when not required, but must have an obstacle free path for lowering. Sometimes the need to reposition other items creates problems with the aesthetic values of the room. There is often a need for an overhead projection surface that can be active while the blackboard is in use, and this is sometimes found as a vertically sloped surface above the blackboards, or as a horizontally sloped surface adjacent to the blackboard. In these instances, the room designer's preference is to paint or finish the surface to match the balance of the walls. The system designer knows that this surface should be a matte white to keep the color balance neutral, and absolutely must be free of texture to avoid image "noise". The room designer views the demands of the system designer as an unwarranted constraint on the creative development of the room design.
The definition of the location of a video projector will usually produce the same negative response from the room designer. As a system designer, you know that you have a limited range of options for the projector location. For most video projectors the center line of the lens can't be located much more than 15 degrees above or below the screen center line. The range of acceptable horizontal image shift is much smaller. CRT projectors have a fixed relationship between screen size and projector location. Many LCD video projectors do not have keystone correction capability, making correct location much more critical. While it is possible to use projector lifts, complicated mirror arrangements, and rear screen systems to allow for unobtrusive projector locations, these usually carry their own potential conflicts with the room designer. The system designer knows that a compromise in projector location will jeopardize the return of value for the hefty capital investment in the projector, and yet it is not uncommon to find the room designer showing the projectors at 20-30 degrees above the projection screen center line, and at some arbitrary distance from the screen to keep the projector tight to the ceiling, even after the system designer has provided the guidelines for its location. There is also a common misconception on the part of room designers that light can travel around or through objects when required by the room design. For people sensitive to the interplay of light and shadow when designing a space, they often seem to be unable to comprehend why having some obstruction in the projection path may be a problem, or why fitting a double mirror system in a space too small to provide freedom from shadowing by the mirrors themselves would be a problem.
After investing all the time in the development of a multi-tiered ceiling with subtle lighting valances, beautifully textured ceiling tiles, and custom fabricated down-lighting fixtures, the room designer does not want to see a free-floating hulk of a video projector, tethered to the ceiling with a stick. Whether it's a boardroom, a training room or a lecture theatre, this front-screen projector location will usually produce some grumbling from the room designer. (Of course in a University lecture theatre, there may be a real concern for the theft potential of a ceiling mounted projector). In those instances where the projector location can't be housed discreetly on the ceiling, negotiating for a rear screen location will help by making the projector invisible, and it will provide the added benefit of higher image contrast with higher levels of ambient room light (more about that in a bit).
The location of viewers also seems to be problematic at times. Even though the system designer can produce all sorts of data on acceptable viewing angles, both horizontal and vertical, this will often be at odds with the proposed seating layout, or the range of proposed seating layouts in spaces that will accommodate more than one. Often the worst possible case will arise when working with a room designer that has done designs for cinemas. It is not at all uncommon to find that viewing angles in the "cheap seats" in the front of a movie theatre exceed the recommended maximums. This is often erroneously justified as being an acceptable byproduct of arriving too late to get good seats. Try watching a subtitled movie from the front row by the wall in some theatres and you'll have no idea what language the subtitles are in. In boardrooms, training rooms and classrooms, there is a reasonable expectation to have no compromised seating due to poor viewing angles. The information being delivered on a screen in these situations must be received with minimum image distortion in every seat. Any seating arrangement that requires the viewer to crane their neck around obstructions, such as other viewers, or to try to decipher the skewed image seen when viewing a screen from 60 degrees off-axis, should be considered unacceptable. The seating arrangement and screen locations are often derived from the programming of a space without adequate square footage to deliver the program. Rather than tell the owner; "No, it's not possible," and risk the perception of failure, the room designer will often make compromises in sight lines and viewing angles without informing the owner of the true extent of the implications. It is not so much a matter of evil intent as an ignorance of what it means when the system designer says; "This will produce a severe compromise in performance in these seats." In these cases the system designer has to wrestle with the different understanding of "compromise" by the room designer and the owner of the facility. The system designer will ultimately take the heat for the compromise, because the system designer is the person the owner associates with the system function and performance. Any paper trail showing where the responsibility for the compromise lies will not correct the damaged perception of competence of the system designer. It is important to be able to identify which conflicts have to fought to the end, as there are some design issues which cannot be compromised, they are more binary in nature, they work or they don't.
The control of ambient light and its effect on the video projection image often leads to a fight of epic proportions. More so in corporate facilities where corporate status has been related directly to window space and a nice view. This isn't restricted to corporate facilities, as lecture theatres and classrooms are often bestowed with the wonder of natural light to provide an open and friendly learning environment. For room designers that have experience with slide projectors and overhead projectors, there is a complete lack of understanding of the magnitude of difference in light output and contrast ratio between a run-of-the-mill slide or overhead projector (where peak white output may actually have some meaning) and most affordable video projectors. The system designer will often find that every time they have referred to a video projector image, the room designer is visualizing a slide or overhead projector, and their own school experience of seeing slides or overheads in a brightly lit classroom. The solution that first comes to mind for many room designers are "grey-out" blinds, the perforated plastic sun-screens, as they are substantially less expensive than true black-out blinds, and there seems to be a perception that they are adequate for use in projection environments. I have actually heard a room designer recommend them on the basis that some other educational facility had them, and that they worked just fine. When I checked with the A/V people in that facility they were aghast, and indicated that the sun screens are a nightmare, barely suitable for blocking the bright afternoon sunshine and that they've been trying to get them changed to black-out blinds since the facility opened. This was a case of a room designer inferring that something worked just fine because it was seen to be used in another facility with similar requirements.
The use of lighting fixtures that shine directly on the screen is also common. With drop-down electric screens, the typical "wall-washer" lamps will shine directly on the screen, and more often than not, the room designer will be visualizing these wall washers as the "low light" fixtures for projection applications. Zoning of room lights is an important consideration, and provision of dimmable fixtures (and the dimmers for them) is a must. In some projects, the lighting design may fall under the auspices of the electrical consultant, who at least may have a basis for discussion regarding actual light levels, and the importance of
Room finishes will often provide unexpected reflections onto the screen surface, either from electric or natural light. When reviewing projector installations, it is important to have some understanding of the intended finishes for surfaces that could affect the image, such as; the boardroom table top, mirrored ceiling tile, glass in picture frames, or the peculiar polished metal sculptures favored by corporate interior designers. Even the glossy hardwood floor in some venues can deliver an amazing amount of light onto the projection screen if there is theatrical type stage lighting for the presenter. We have had projects where we had to review a dozen different floor finishes for reflectivity and diffusiveness of light falling on it before approving one. You might imagine how that was received by the room designer, who had a much different vision for the floor finish.
There is little value in talking about the difference in image quality, the most effective way to communicate is to demonstrate the difference. If the designer's office has a meeting room with natural light, that would be the ideal location for a presentation of the effects of ambient light. A combination of overhead transparencies and an LCD panel can quickly demonstrate the loss of effectiveness of a video image in situations where there are high ambient light levels. The trick here is to take the specific example and ensure that they understand that this can be applied generally, not just to that LCD panel in their meeting room.
Are these issues unresolvable? If push comes to shove, the system designer can usually get the owner to force the room designer to provide the accommodation of the technical systems, usually at the expense of a cordial working relationship with the room designer. Some fights are worth fighting, and some are better pursued with a negotiated settlement. It helps to understand that the room designer is not necessarily just being contrary, sometimes they just have no experience to relate to what is being said by the system designer.
United Entertainment Media Inc.