For the audience, the visibility of the athlete is related to the vertical illumination and the level illumination. The vertical illuminance depends on the direction and position of the football field lights, see Figure 4.
Because the level of illumination is easy to calculate and measure, the illuminance recommended value refers to the level of illumination. The number of spectators due to the different venues, and viewing distance and the capacity of the stadium, so the required illuminance according to the above table requirements with the increase in stadiums.
Illuminance Uniformity In fact, the illuminance is absolutely uniform is impossible to achieve. Illuminance uniformity can be expressed by the ratio of minimum Emin of illumination to the maximum Emax, and the minimum Emin of illuminance can be expressed as the ratio of eave to the average value.
Illuminance uniformity should be at least emin/eave=1:1. 5, the low illumination in the above table situation, due to a variety of practical factors constraints, the ideal illuminance uniformity is difficult to achieve. In this case, the illuminance uniformity should be no less than 1:2 as long as the lighting of football stadium lights arrangement position and economic conditions permit. 5, assuming that the position of the Luminaire meets 4. Although the illuminance uniformity of the field meets the requirement, it is needed to avoid mutation of illumination in a short distance.
Brightness uniformity In addition to the above illuminance uniformity, it is noteworthy that the human eye is to see brightness rather than illuminance. The appearance of the stadium will vary depending on the direction of viewing, the conditions of the game and the weather.