Stadium lighting design is mainly to meet the needs of football, athletics, football, hockey and other sports. The movement of football is not only on the ground, but also in the space of 10-30 meters from the ground. Therefore, it is necessary to maintain a certain brightness in all directions of a certain space height. Generally, the light distribution in a space below 15 meters above a football field must be very uniform.
Most of the track and field competitions are performed within a height of about 3 meters from the ground. The lighting of this type of sports facilities mainly meets the requirements for uniform light distribution on the ground. Sports such as javelin, discus, and hammer can reach a height of 20 meters. Originally, these events were often not held at night, but now these events are often held at night, and they are often finals or qualifying matches. The importance is evident. Therefore, the venue lighting must meet the needs of such projects.
In order to meet the requirements of color TV live broadcasting, especially HDTV broadcasting, the brightness ratio between athletes and the venue and the audience should have a certain value.
Stadium lighting requirements
To do a good stadium lighting design, the designer must first understand and master the stadium lighting requirements: there should be sufficient illuminance and uniformity of illuminance, no glare lighting, appropriate shadow effects, and correctness of the light source chromaticity parameters.
1). Illumination requirements
The color television broadcast lighting should be designed with the vertical illumination of the venue as the main index. The lighting of the venue must generally meet the requirements of athletes, referees, spectators and cameras. For this reason, the horizontal illuminance, vertical illuminance, and brightness when the camera takes a panoramic picture must be consistent. The brightness change ratio between athletes, venues and spectators must not exceed a certain value (a value that affects the camera quality of the camera), so as to meet the requirements of color TV camera.
Color television broadcasts require higher illuminance than black and white televisions, and high-definition television broadcasts require higher illuminances than standard-definition color television broadcasts. Ultra-high-definition television broadcasts are now also being tested, and lighting requirements will be higher. In addition, the illuminance is closely related to the size of the TV screen. If the illuminance is low, then the TV broadcast is limited to capturing the panorama; if the illuminance is high, you can capture the panorama and take close-up shots, so that the TV broadcast is more vivid.
2). Illumination uniformity
The requirement for uniformity mainly comes from the requirements of television cameras, and disproportionate uniformity will also cause visual pain to athletes and audiences. The illuminance uniformity is defined as the ratio of the minimum illuminance to the maximum illuminance U1 on the surface, and the ratio of the minimum illuminance to the average illuminance U2. Uniformity is used to control the viewing conditions on the entire site. U1 is good for viewing functions and U2 is good for viewing comfort.
The average illuminance measured in the range of 1.0-1.5 meters high on the playing field perpendicular to the main direction of the lens axis should not be less than 1400lx, in fact 1000lx is also possible for photography.
For a stadium with a large area (such as a stadium with a runway, the area is 120mX200m), the uniformity of horizontal illumination is not as good as the uniformity of the football field. It is necessary to ensure that the television camera can capture high-quality television pictures while maintaining the illuminance gradient required for rebroadcasting and meeting the requirements for uniformity of illuminance.
The faster the athlete moves and the smaller the exercise equipment, the stricter the requirements for vertical illumination, illumination uniformity and illumination gradient.
When color broadcasting a football game, the rate of change in illumination between adjacent grid points on the horizontal or vertical plane should not exceed 20% every 5m, and it should not exceed 50% when non-color TV broadcasting.
3). Brightness and glare
The function of a television camera is somewhat similar to human vision. Both the camera and the human eye use the intensity of the perceived illumination as the brightness. Therefore, the picture contrast and its background are the most important for the picture quality. On the one hand, due to the lack of sufficient contrast, good pictures cannot be obtained; on the other hand, it is difficult to handle light and dark, which also hinders the production of high-quality pictures.
Brightness and glare are important to the visual comfort of athletes and spectators. Considering that to avoid too dark background, part of the light should be directed to the stands. The average horizontal illumination of the auditorium seating surface should meet the requirements of 100lux. The illuminance should not be lower than 200lx / the vertical illuminance of the auditorium near the first 12 rows (15 rows) of the competition area should not be less than 25% of the vertical illuminance of the venue. This not only reduces the glare of the audience on the opposite stand, but also makes the TV picture more favorable because of a bright stand background.
In general, glare is largely determined by the brightness of lighting facilities, the physical angle of the luminaire arrangement, the area of light, the angle between the direction of the luminaire and the normal viewing direction, the brightness of the lighting facility and its background brightness when viewed. The relationship between them, as well as the conditions to which the human eye adapts (mainly determined by the brightness of the visual field) and a series of factors. If you want to obtain comfortable viewing conditions, the direct brightness in the field of view must not exceed a certain brightness value that the background can be based on.
The glare problem can be solved as long as the contradiction between the audience and the athlete is coordinated. This coordination is done by the designer, that is, the light distribution of the flood light, the installation plan, the height of the lamp suspension and other factors should be considered when designing. Wide-speed light projectors are easy to obtain the uniform effect of the venue, but will increase the glare to the audience on the stands. Therefore, a combination of medium-beam and narrow-beam projectors is appropriately used to solve the glare problem.
4). Shadow effect
The strong contrast of brightness and the shadows at the same time hinder the correct adjustment of the TV camera, which will affect the quality of the TV picture. Too dark will also reduce visual comfort. On the other hand, shadows are very important for television transmission and viewers, especially when football games with fast-moving high-speed passing characteristics. If there are shadow effects, the audience from the players cannot track the goal. You can fine-tune the floodlights, while avoiding the adverse factors that affect the lighting, you can improve or eliminate the effects of shadows. However, the shadow of the stadium under the canopy is difficult to avoid, even if artificial lighting is used to supplement the light.
5). Color correction
Color correction is important for both viewers and color TV broadcasts. The color temperature of the TV camera can be adjusted within a wide range, and the light source with a color temperature of 3000K-6000K can be used for TV broadcasting. However, the stadium is an outdoor sports field. When choosing a light source, the color temperature of daylight should be considered, that is, 5000-6000K. This may happen. The game starts in daylight and ends in cold light when the sun sets (usually Use the word “all-weather” to describe this situation). Under the dual light of sunset and artificial lighting, the color temperature of daylight is required to be consistent with the color temperature of the artificial lighting source, so that the TV camera can continuously broadcast and smoothly transition from daylight to artificial lighting.
Metal halide lamps are widely used in venue lighting, with a color temperature of 4000-6000K, which can fully meet the needs of outdoor color TV broadcasts. In recent years, LEDs have become more and more widely used in venue lighting.