The Pros And Cons Of A Video-Based Control System

These days, architectural designers are looking to theatrical systems integrators (TSIs) as a technical resource for many complex lighting control projects, and the 7 World Trade Center reconstruction project was no exception.

Because the LED package is so large, it was important to the owner that the supply of fixtures be sent out to multiple manufacturers for a competitive bid. The problem for a system this specialized was that each manufacturer wanted to use proprietary control protocol. This made it not only difficult to select an LED fixture manufacturer, but also to make a comparative analysis of the bids.

After an extensive evaluation process, the control for the LED wall was awarded to LED Effects located in Rancho Cordova, CA. Once LED Effects joined the team, its unique control protocol offered some additional advantages that DMX512 could not. At no additional cost to the owner, the system adopted the LED Effects Stream protocol, which is an RS232-based system that uses standard computer edge-servers and is driven by video clips instead of a theatrical control console.

The Stream protocol gave the system the added feature of bi-directional communication to support a temperature feedback from the LED fixtures. By receiving constant reports, the control system manages the intensity of the fixtures and can even turn them off in case of extreme heat. The key component to maintaining the life expectancy of an LED is the ability to regulate the temperature of the LEDs. The concern was raised about direct sunlight on the fixture and how much time it would take after sundown for the fixtures to cool enough to be energized. With this added talkback feature, the guesswork is taken out of the equation, assuring the longevity of the LED.

One may ask, “Why not use the new RDM protocol, which also fully supports bidirectional communication?'' This was carefully considered. Pathway Connectivity created a Pathport Network proposal using RDM and presented it to the team. The design was sound and showed the ability of RDM to handle the massive amount of data being generated by the interactive camera-recognition system. The owner was then asked who should decide which way was best. This was a difficult question in a situation where two industries collided, and the fixture manufacturer was suggesting video, while the TSI comfort level rests with tried-and-true DMX.

An additional advantage to the Stream system is using a video platform to program. Video has the simple ability to generate a scene from a video clip or picture. A video clip is instantaneous and can be posted to the low-resolution video wall in a matter of minutes. The speed and intricate detail in generating the scenes using video is far more efficient as compared to the time it would take to build the scene using a traditional DMX system.

While posting and viewing video clips in real time is speedy, creating and editing pose problems. Today's biggest obstacle with video is the ability to make changes to the lighting program in real time. Most of the updates must be made offline because the video programming is very time-consuming. As a result, the LD loses the ability to sit with the console operator and update the show in a matter of minutes. This also eliminates the trial-and-error process and makes updating look much more time-consuming, as well as requiring additional offline programming time. Despite this obstacle, Stream worked well for 7 WTC.

This project is a great example of video and computer networks impacting the entertainment controls industry. Peter Rogers, vice president, marketing, of Strand Lighting advises, “The integration firm that invests in the computer network training for its staff will be the pioneer firm of the future.” The concept of a network being wired into a lighting control system of today is nothing new, but we, as an industry, have just scratched the surface of what the computer technology for video can offer. Products from companies like High End Systems and Pharos are on the right track, but they will not be fully effective until we can use video to manipulate lighting looks in real time.