Angles Of Reflection
Leave it to human ingenuity to take the hassle out of long distance communication. It used to be that if, for example, you needed to send word of Greece’s victory in battle back to Athens, it involved sending someone out to run a marathon. I would guess that messenger had plenty of time along the way to reflect on how nice it would be to talk to someone miles away without needing to travel every one of those miles first. If so, he would be thrilled to know that we have spent the last few millennia finding all sorts of ways to communicate across even greater distances and with ever-increasing levels of sophistication. While none of these methods quite fully capture the experience of the original and still popular face to face conversation, we do come very close with…
Large Format Videoconferencing
What we mean by “large format” is any videoconferencing system in which the images being transmitted between users end up on a display that is big enough to be approximately life-sized. This is significant because much of the point of using videoconferencing at all is for the way it allows the nuance of communicating directly and in person to be replicated between remote locations. Body language, facial expressions and everything else we express nonverbally while speaking are all available with videoconferencing but only if presented at a scale that can be easily seen by others. When your conversation partners have been significantly miniaturized by a small screen, the benefits of the conversation’s visual component are in danger of shrinking as well.
None of this should be taken to mean that so-called small format videoconferencing is in any way invalid. This approach has its own unique advantages, especially in that it offers a level of portability that is all but impossible to emulate in a larger format. A couple of flat panel displays on a mobile equipment cart can be moved between rooms with an ease that leaves large format displays quite literally behind. In permanent installations with sufficient space, however, large format is definitely recommended for its potential to make better use of the immersive nature of video.
“Immersive” may be a word not often found outside the context of entertainment or simulation but I think it is relevant here because videoconferencing really should be thought of as a branch of simulation. Mundane though it may sound, it acts as a sort of meeting simulator that quite handily removes the need to actually meet in order to collaborate. Since collaboration is at its best when everyone is focused on the task at hand, videoconferencing equipment should mimic reality as closely as possible and not introduce distractions and limitations.
One obstacle on the path of reaching this goal is the proper use of lighting. At a minimum, the faces of the participants and anything else that needs to be seen clearly across the video feed must be well lit. The typical lighting scheme in most offices is great at illuminating horizontal surfaces like desktops but is not always sufficient to make a group of people look presentable on camera. Complicated stage lighting is not really necessary but additional diffused light sources aimed to keep faces lit instead of the tops of heads will make an appreciable contribution towards enhancing the system overall.
Lighting matters become more complicated when there are significant competing light sources visible to the camera. The issue here is that most cameras automatically adjust exposure to keep the overall light level in the scene from being either too dark or too light. Any bright window or light fixture in the shot can skew that level to the point where the camera’s compensation causes everything else in the room to look rather dark by comparison. Either these sources need to be avoided by the camera, treated in some way or, again, additional lighting is needed to ensure that everyone is adequately lit.
At this point, it may begin to seem as though using two piece projection for this sort of application would fail because of the considerable light requirements for videoconferencing and the diminished performance of projection in bright environments. The key to making the two work together is to keep all of this lighting under control.
As in any projection application, controlling light does not have to mean eliminating it altogether. Simply increasing the amount of light for the sake of being able to see the people speaking will not necessarily ruin the image on the screen, so long as those lights are not too close to the screen and, more importantly, are not aimed towards it.
In addition to the care necessary to keep light from hitting the screen directly, secondary reflections will need to be considered as well. This indirect light will not be as intense as direct light but can still become objectionable unless adequately controlled. Often the most reasonable way of doing this is to use a dark color palette for the walls and furniture and to avoid glossy or reflective surfaces as much as possible. The goal here is for the objects and coverings in the projection environment to absorb light that would otherwise continue to be reflected within the room and potentially reach the screen.
Even having taken these measures, the amount of ambient light present with videoconferencing is likely to exceed what would be found under ideal circumstances for projection. To further combat this, a “high contrast” projection screen that includes some gray pigmentation can further improve the image by absorbing a portion of that extraneous light. This absorption lowers the black level on the screen which yields a higher contrast image. The end result improves the appearance of the video and goes a long way towards guaranteeing that the message gets through.
Our Greek friend may have needed to go an even longer way to achieve similar goals but then, that’s the sort of difference a few thousand years can make. Fortunately, it has not taken nearly as long to make dramatic progress in videoconferencing and the infrastructure it relies upon. As these – and as projectors and screens – continue to improve, the quality of the experience will as well. At the very least, it will be a lot easier to gather everyone to collaborate on it than ever before.
-- Adam Teevan
ateevan@da-lite.com
Download in PDF Format (550.7kb)