# Applied Research of the UAV Illumination Measurement System in Sports Stadiums
## 3 Results
### Illumination Data Processing  
In the process of drone illumination acquisition, the drone hovers over the illumination collection point for 3 min and transmits the collected illumination to the OneNET cloud platform in 3-s intervals. The cloud platform data is shown in Figure 15.  
The platform is showing an illuminance value of 542 k at the moment. Furthermore, two switches are displayed in the cloud platform, one indicating whether the system is currently in a data collection state and the other controlling whether illumination collection is on or off. Based on the data collected, the acquired illuminance data can be plotted as a real-time variation curve. In the line graph, the horizontal axis is the time of illuminance acquisition, and the vertical axis is the current illuminance value. The curve acquires the current measured illuminance value at a refresh rate of every 3 s. In addition, the current illuminance collection height can be set into the illuminance collection system via the cloud  
Figure 14: The UAV flight log data. Figure 15: Cloud platform showing illumination data. platform. Illuminance at 4 M height in the stadium was acquired by this method. The UAV is flown to the designated measurement point and hovered for 3 min to get the illuminance data of the point, in order to calculate the illuminance data of the measurement point more accurately. The illuminance data for one measurement point is shown in Table 2.  
As shown in Table 2, The measurement system got the illuminance data at 3-s intervals and transmitted the collected data to the cloud platform. The illumination acquisition system takes 120 s to get data at the measurement point, for a total of 60 data. Then, the outliers in the illuminance data at the collection points can be rejected, using the thresholds determined by the LOF algorithm. The rejection of outliers at measurement points is shown in Figure 16.  
The horizontal axis represents the time of acquisition, and the vertical axis is the illuminance value. It can be drawn that outliers marked in red are selected obviously; at the same time, the others are judged to be normal values and are marked in blue by analyzing the images. In addition, it can be seen that the distribution of normal values is concentrated with an error of around 50 lx. By calculation, the average value of 550.69 lx with the outliers removed is the illuminance value for that point. Based on the data obtained from the illuminance measurement-collection experiment, the horizontal distribution of illuminance at a height of 4 m above ground level was explored, as shown in Figure 17. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Time (s)** & **Value (lx)** & **Time (s)** & **Value (lx)** & **Time (s)** & **Value (lx)** & **Time (s)** & **Value (lx)** \\ \hline
3 & 591 & 48 & 553 & 93 & 545 & 138 & 586 \\
6 & 538 & 51 & 556 & 96 & 547 & 141 & 505 \\
9 & 497 & 54 & 556 & 99 & 544 & 144 & 508 \\
12 & 485 & 57 & 554 & 102 & 545 & 147 & 591 \\
15 & 489 & 60 & 556 & 105 & 542 & 150 & 596 \\
18 & 476 & 63 & 572 & 108 & 553 & 153 & 495 \\
21 & 537 & 66 & 562 & 111 & 548 & 156 & 543 \\
24 & 542 & 69 & 563 & 114 & 551 & 159 & 547 \\
27 & 543 & 72 & 564 & 117 & 550 & 162 & 537 \\
30 & 541 & 75 & 564 & 120 & 550 & 165 & 542 \\
33 & 555 & 78 & 536 & 123 & 561 & 168 & 557 \\
36 & 549 & 81 & 539 & 126 & 563 & 171 & 551 \\
39 & 549 & 84 & 537 & 129 & 562 & 174 & 556 \\
42 & 549 & 87 & 533 & 132 & 566 & 177 & 548 \\
45 & 550 & 90 & 532 & 135 & 562 & 180 & 545 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Illuminance values acquired by the system. Figure 16: Outlier handling of collected data. As shown in Figure 17, the distribution of illumination in the stadium becomes more complex as the height increases.