Since snowboarding became an Olympic event at the 1998 Nagano Games, the International Ski Federation -- Federation Internationale de Ski, or FIS -- has set the rules for half pipe competition and judging. Since the half pipe isn't a race, judging is necessarily subjective. While your average spectator may not be able to tell a corkscrew from a McTwist, judges must meet high standards to be selected by the FIS for the Olympic panel, including experience judging a minimum of eight FIS World Cups in the two years before the Games.
The FIS provides basic dimensions and standards for half pipes constructed for the Olympics. A half pipe, as the name suggests, looks like half a pipe, laid into the snow. The bottom is almost flat, while the walls are concave. An Olympic half pipe runs about the length of one and a half football fields and is between 50 and 62 feet wide. The walls rise 14 to 16 feet over the surface at a 15- to 18-degree incline. Riders drop into the pipe from an elevated starting platform, which must extend across the entire width of the pipe without variation. This ensures no rider gains any advantage by dropping in on one side or the other.
Riders advance through three stages of competition on their quest for Olympic glory. Competition begins with all riders taking two runs in the qualifiers. The riders with the top six qualifying scores advance straight to the finals, while the rest head to the semifinal round to vie for the remaining six spots in the finals. In the final medal round, riders take two runs, with only the best of the two counting as the rider's final score.
Each of the six judges evaluates each run independently without discussing the score with the other judges. FIS instructs judges to score their overall impression of the entire run out of 100 points. Judges evaluate tricks individually and tally up points for the rider's execution, as well as considering overall difficulty and how the rider uses the pipe. Riders aren't required to perform any specific tricks or a certain number of tricks, although the typical half pipe run includes between five and seven hits. Historically, Olympic riders were required to do one "straight air" -- as high as possible without any twists or flips -- this requirement was eliminated at the 2014 Sochi Games.
Judges evaluate each trick or combination of tricks separately to arrive at their final score. Riders score more points for having a wide variety of tricks, including difficult tricks or combinations, for inventing new tricks and, of course, for getting big air. Master snowboarders remain in control throughout their runs, and judges deduct points for moments where riders demonstrate a loss of control. A small mistake such as a hand touching the pipe briefly may only result in a deduction of 10 points or fewer, but a rider who falls over or sits down could be looking at losing as many as 25 points.