Keeping both eyes on the ball

Bob Pank#

Author: Bob Pank#

Published 1st September 2011


It goes without saying that spectator sports are made for television; of course they are, as can easily be proved by trying to follow a football match on radio. A skilled radio commentator can describe key aspects of the action fairly well but television actually gives viewers the impression that they are sitting in the stadium.
Widescreen high definition does a much better job than the old four-by-three SD, freeing the programme director to deliver wide-angle shots of players approaching the the ball rather than an often confusing series of close-ups. HD provides plenty of detail from which television viewers can select the elements they want to concentrate on.
3D makes the whole experience even more realistic by delivering the depth information that is otherwise only available to spectators actually present in the stadium. This is equally apparent to anyone trying to play the chess game that comes in modern versions of Windows or OS X. It is much easier to play this type of game with a top-down bird’s-eye view of the board than by trying to isolate a specific depth layer in a 2D image. Here again, 3D has the potential to make a lot of computer software, not only games, much easier on the eye.
A complicating factor when televising stadium events such as football matches in 3D is the brain’s tendency to interpret a wide-angle field view as some kind of tabletop miniature model with each player perhaps two inches high. This illusion can be overcome by cutting between long and medium shots. It also raises the question of whether a 3D programme needs to be optimised for a specific screen size. BSkyB’s Technical Guidelines for Plano Stereoscopic (3D) Programme Content specifically mention a screen range from 46 to 70 inches. The specified depth budget of -1% to +2% or a range of 3% should also work for theatre-sized screening.
The main problem is that the focal lengths typically used with telephoto lenses in sports can easily produce a limited range of disparity. This has the effect of making each player, and very commonly the entire distant terrace, look like a flat layer of cardboard.
Cutting between all these shots creates a potential for serious jumps in depth disparity. A stereoscopic analyser like the Cel-Scope3D is really essential to confirm what each camera’s setting is going to be throwing at the viewer during the match. It can also activate an alarm or show a depth chart if a particular camera feed is showing 3D outside the broadcaster’s limits – or perhaps no 3D at all!

* Robin Palmer is Managing Director of Cel-Soft. He is currently involved with software solutions for 3D & TV quality control and measurement technology.

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