Stadium lighting design is mainly to meet the needs of football,athletics,volleyball,tennis,hockey and other sports.For example,because the trajectory of the ball is not only on the ground,but also in a space 10-20m away from the ground,a certain brightness must be maintained in all directions at a certain height of the space.Generally,the space below 15m above the football field,the light distribution should be very even.
Most athletics competitions are held at a height of about 3m from the ground.The lighting of such sports facilities,mainly meets the requirements of uniform light distribution on the ground.The javelin,discus,and other sports can reach 20 meters.In the past,such sports were often not held at night,but now these sports are held more at night,and they are often finals or qualifying matches.Therefore,Led site lighting must meet the needs of such projects. In order to be suitable for the requirements of color TV live broadcast,especially high-definition TV broadcast,it is required that led stadium flood light brightness ratio between athletes,venues and audiences should have a certain value.
To do a good stadium lighting design,the designer must first understand and master the lighting requirements of the stadium.There should be sufficient illuminance and lighting uniformity,glare-free stadium led flood lighting,appropriate shadow effects,correctness of light source chromaticity parameters,etc.,
As follows describe qualitatively.
1) Illumination requirements:
Color TV broadcast lighting should take the vertical illuminance of the venue as the main design indicator,and the venue lighting must generally meet the requirements of athletes, spectators and cameras.For this reason,the horizontal illuminance,vertical illuminance and the brightness of the camera when shooting the panoramic picture must be kept consistent. The brightness change ratio between athletes,venues and spectators must not exceed a certain value,so as to meet the requirements of color TV cameras.
2) Uniformity of illumination:
The requirements for uniformity are mainly due to the requirements of TV cameras,and disproportionate uniformity will also bring visual pain to athletes and spectators.Illuminance uniformity specifies the ratio (U1) of the minimum illuminance (Emin) to the maximum illuminance (Emax) on the surface,and the ratio (U2) of the minimum illuminance (Emin) to the average illuminance (Eave).Uniformity is used to control the viewing conditions on the entire field,and U1 is conducive to the viewing function,U2 is good for visual comfort.The average illuminance measured within a height range of 1.0-1.5m on the playing field perpendicular to the main direction of the lens axis should not be lower than 1400lx.In fact,1000 lux is also possible for photography.
For a sports venue with a fairly large area(such as area is 120m×200m,track around the stadium),The uniformity of its horizontal illuminance is not as good as the football field.In order to ensure that the TV camera can capture high-quality TV images,It is necessary to maintain the illuminance gradient required for broadcasting and meet the requirements of illuminance uniformity.Athletes move quickly in the sports filed and have strict requirements on vertical illuminance, illuminance uniformity and illuminance gradient. When broadcasting football games in color,the illuminance change rate between adjacent grid points on the horizontal or vertical plane shall not exceed 20% per 5m,and shall not exceed 50% in non-color TV broadcasting.
3) Brightness and Glare
The function of a TV camera is somewhat similar to human vision,both the camera and the human eye use the intensity of the perceived lighting 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, a good picture cannot be obtained; on the other hand, because it is difficult to deal with light and dark,it also hinders the production of high-quality pictures.Brightness and glare are important for the visual comfort of athletes and spectators,considering the need to avoid a too dark background,part of the light should be directed towards the stands,the average horizontal illuminance of the auditorium seating surface should meet the requirement of 100 lx,and the illuminance of the rostrum should not be lower than 200 lx,the vertical illuminance of the auditorium in the first 12 rows (15 rows) near 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 has a bright stand background on the TV screen,which is more beneficial to the picture quality.
In general,glare is largely determined by the brightness of the lighting facility,the physical angle of the lamp arrangement,the area of light emitting,the angle between the direction of the lamp and the normal viewing direction,and the relationship between the lighting brightness and the background brightness when viewing.It is determined by a series of factors such as the relationship between the human eye and the conditions for the human eye to adapt.
The glare problem,that isthe light distribution of the floodlight,the installation scheme,the height of the lamp suspension and other factors should be considered in the design.Wide beam floodlights are easy to obtain a uniform effect on the site,but will increase the glare of the audience on the stands.Therefore, a combination of medium beam and narrow beam floodlights is properly selected to solve the glare problem.
4) Shadow effect
Strong brightness contrast and shadows at the same time,hinder the correct adjustment of the TV camera,thus affecting the quality of the TV picture.Too dark will also reduce visual comfort.On the other hand,shadows are important to telecasts and viewers,especially when football games are characterized by fast-moving high-speed passes,If there are shadows, spectators far away from the ball will not be able to track the target.The led sports flood light can be finely adjusted,and the influence of the shadow can be improved or eliminated by avoiding the unfavorable factors affecting the lighting.But for the stadium with a canopy,the shadow under the sun is difficult to avoid,although artificial lighting is used for supplementary light to no avail.
