Understanding a Light Plot
When working on a live event, it is important for designers in all disciplines to effectively communicate their ideas and intentions to their clients, their design teammates, and the crew that will be building the show. Typically designers will use a drafting program such as Vectorworks to create a layout (plot), and each design team will share the same plot to draw where the lighting, audio, video, LED, and scenic elements will be placed. A working drawing gives everyone involved the ability to plan for the three-dimensional space and work around each other to create the intended design as quickly and smoothly as time will allow.
This week we will break down the elements of a lighting plot. Lighting Plots give information to the crew and design team of what lighting elements are being used, where the lights are being placed, what kind of hanging position the lights will be attached to, and details specific to each fixture. Light plots can cover shows that have hundreds of fixtures in an arena setting laid out on a large-scale printout, or they can cover a smaller design on an 8 ½” x 11” diagram. It is up to the designer to use this medium to communicate exactly what is needed.
Initial Drawing of a Light Plot
Once a show design has begun, the layout will be built to suit the venue, and hanging positions will be added to the plot. In a ballroom or arena the lights are hung from trusses that are suspended from the venue hang points. The LD will determine the lighting fixture needs based on the type of trusses or pipes in use, the distance from the stage for each hanging location, and the height of the hanging position relative to the height of the presenter on stage. As the lights are added to the plot, information will be included for each lighting fixture – fixture channel number, dmx address, power circuit, color, focus. There are no set-in-stone rules to a lighting plot, but it is important to have clear instructions in your plot to your crew all the same.
Lighting instruments are assigned plot data based on the needs of each light. Incandescent lights often require less information per fixture as each light is assigned a channel number in the console, a dimmer number to supply electricity to the light, a circuit number from a cable that connects the light to the dimmer, a focus point, and a gel number for the color. LED and moving light fixtures will not require the gel number, but they will need dmx universe assigned since moving lights typically span multiple universes.
Light Plot Details
The amount of information appearing on a light plot depends on the need for the drawing. For the crew hanging the lights, a plot with hanging and circuiting information is required. Channel (x) plugs into socapex circuit (x). For a designer or assistant designer focusing the show, a focus plot is more critical in keeping tabs on where lights are scheduled to be focused. Channel (x) focuses on position (x).
Note: It is important to have a detailed plot without the clutter of excessive details. Theatrical plots have traditionally used containers (circles, squares, triangles) to denote dimmer, channel, and circuit info. We tend to minimize visual clutter by removing containers altogether.
Dimensions on a Light Plot
With all the information contained in a light plot, dimensions are a critical component when communicating a design. Moving lights need enough space for the heads of the units to pan and tilt, and ellipsoidals typically need 18” to be able to properly focus the unit. A front wash for stage might have lights spaced apart between 6 or 8 feet each per light for a system, and this would be pertinent as the focus of the lights are noticeable on camera if the distances vary. Drawing dimensions are critical in ensuring precision.
Light Plot Legend
The final element to a lighting plot is the legend. Like any map, the legend is important to show what each symbol represents in the map. The legend lists all the lighting fixtures used, and what the labels will entail for the plot itself. We take a further step to simplify things on show site by coloring our standard lighting fixture symbols to match the colors that each fixture style contains. It is typically simpler to have a stagehand grab the blue fixture that matches the blue fixture on the plot, and you cut short the option of a plot being misinterpreted.
A good lighting plot is an effective communication tool, and a good lighting plot can save time on show site by addressing questions and concerns in advance of load-in. The ability to hand over a plot to a crew and have the show accurately installed with little to no troubleshooting is its own art form.