A new innovation is changing the way theatres and stadiums are designed and engineered, writes Peter Fearnside.
Every building, in order to satisfy its reason for being, must consider function before experimenting with form. Few constructions demonstrate this fact better than theatres
and stadiums, where sight and sound are key priorities.
Sightline analysis has long been an important consideration in the design of theatres and stadiums. But the methods previously used have been far from perfect and have not always provided the best outcomes for venue managers or the people paying to attend a performance or sporting event.
For the earliest attempts at sightline analysis, simple 2D cross-sections were drawn through a theatre or stadium. The seating rake was adjusted so that there were direct lines of sight to a single point on the stage, which assumed an average height for the heads of the patrons in front of a viewer’s position.
With the use of 3D computer models, it was possible to extend this procedure and calculate the sightlines from all audience seats. This also enabled the view from each seat to be visualised using standard head and shoulder models.
The problem with this method is that it assumes audiences at every performance or sports event only view a single point on a stage or pitch. It also assumes people’s heads don’t move throughout a performance, and that audience members have only one eye placed in the middle of their forehead.
Consider the demands of a stage play, where large expanses of the stage must be visible to the majority of audience members, or a subtitled movie, where an entire film screen, and particularly the lower part of that screen, must be visible. For an orchestra performance, complete visibility of all musicians is not vital, but for a ballet performance, a view of the dancers’ feet is essential.
A new point of view
Over the past 20 years, in China alone, Marshall Day Acoustics has designed seven concert halls, 15 opera houses and more than 25 theatres. What we realised is that one of the biggest problems in new performing arts venues is sight lines.
With 3D computer-aided design models, you can effectively sit in each seat, in a digital environment, and see the view of the stage, as well as silhouettes of the people in front of you. But the assessment of whether the view is good enough has been a subjective one.
For our Sightlines program, we wrote computer routines that look to the stage from the perspective of every person in every seat.
The result is a system that works out objectively which parts of the stage people in particular seats can see and which they can’t. It delivers colour-coded maps of the stage as well as the audience areas, showing the range of viewing quality from seats for any type of performance or sporting event.
Sightlines can account for audience’s heads when a spectator looks across the venue to see a goal line on a sporting field, and it can determine how balcony fronts and handrails affect the views of audience members throughout the venue.
With Sightlines, analysis can be undertaken at a very early stage of the design process. It allows a designer, architect or engineer to optimise all sightlines and accurately engineer the seat rake and the height and position of handrails and balcony fronts. Analysis of existing venues allows managers or ticketing agents to categorise seats objectively, and to figure out which should be a $100 seat and which should be a $20 seat for specific types of performances or events.
When audience members would want to see performers’ feet during an event, such as dance or sport, Sightlines can prioritise this in the analysis. For a symphony, where audiences do not need to see the stage floor, you can elevate the viewing plane. Sightlines can examine the viewing angles for the audience to allow seats to be placed to avoid oblique views. This means we can more easily design for specific uses.
In the past, most sightline modelling was done from the point of view of a single eye, but having two eyes means we can see around objects. In developing Sightlines, we studied the way people move to improve their view, rather than sitting still behind the handrail or a person with big hair.
Sightlines is particularly valuable during the design and construction of concert halls, theatres, convention centres, cinemas, sports venues and stadiums. It offers defaults for dance, drama, opera and orchestral uses, and considers the distance to the stage, height above the stage, head elevation, angle of view, rotation of an audience member’s head and vertical inclination.
Sightlines can represent results in a simple colour map that clearly shows areas of seating that require better design, individual seats that are weaker than others for particular purposes, and an overall analysis of the ‘visual health’ of the venue for specific uses.
By changing the event type, involving the stage depth, width or layout changes (between new sets for theatrical productions, for example), data on sightlines from particular parts of the venue can be updated to help with stage design strategies, as well as ticket pricing.
This is good news for the designer, engineer, venue manager or ticketing manager. And for the audience member, Sightlines offers a new level of enjoyment of the event they came to watch.
Peter Fearnside is the founding partner and CEO of Marshall Day Acoustics Australia.
This article was originally published as “Look sharp” in the November 2018 issue of create.