*2.1. Study Area and Sensors*

A field experiment was established at the Texas A&M AgriLife Research and Extension Center in Corpus Christi, TX (Latitude 27◦46'59" N and longitude 97◦34'13" W). The trial consisted of 5 cotton genotypes from the Texas A&M AgriLife Cotton Breeding Program (presented in Figure 1). Genotypes were planted 22 March 2017 in skip and solid row patterns (i.e., one- or two-row plots, respectively), and each was replicated four times. For canopy cover estimation, another field experiment was established at the same location in 2018. The trial consisted of 10 cotton genotypes from the Texas A&M AgriLife Cotton Breeding Program. Genotypes were planted in the first week of April in skip and solid row patterns. To maintain the integrity of the experiment, only part of the field which is highlighted by yellow boxes in Figure 1, was considered for both 2017 and 2018, as the selected area was the only area which had an alternate pattern of skip and non-skip rows and a common variety. The selected area was divided into 1 x 1 m size grids. The number of grids in 2017 and 2018 experiments was 300 and 600, respectively.

RGB and MS sensors were used for this study, as presented in Figure 2. A DJI Phantom 4 Pro (SZ DJI Technology Co., Ltd., Shenzhen, China) was used for RGB data collection. It comprised a 3-axis gimbal-stabilized RGB sensor with a resolution of 20 mega pixels. MS data were collected using the DJI Matrice 100 platform (SZ DJI Technology Co., Ltd., Shenzhen, China) with a SlantRange 3p sensor (Slantrange Inc, San Diego, CA) equipped with integrated solar spectrometer for frame-to-frame, radiometrically accurate reflectance measurements. The sensor has a spatial resolution of 4.8 cm/pixel at 120 m above ground level. It collects data using four spectral bands, namely green, red, red-edge, and near infrared bands, for which the peak wavelengths are presented in Table 1.

*Remote Sens.* **2019**, *10*, x FOR PEER REVIEW 4 of 17

(**a**) (**b**)

*Remote Sens.* **2019**, *10*, x FOR PEER REVIEW 4 of 17

**Figure 1.** Experimental field setup consisted of cotton in skip and solid row patterns in: (**a**) 2017 and (**b**) 2018. The experimental field setup is presented with an RGB (red, green, and blue) orthomosaic of the study area on June 7, 2017, and June 6, 2018. **Figure 1.** Experimental field setup consisted of cotton in skip and solid row patterns in: (**a**) 2017 and (**b**) 2018. The experimental field setup is presented with an RGB (red, green, and blue) orthomosaic of the study area on June 7, 2017, and June 6, 2018. Red 655 35 Red-edge 710 20 Near infrared 830 110

Red 655 35 Red-edge 710 20 Near infrared 830 110 **Figure 2.** RGB and multispectral sensors used for data collection. (**a**) The DJI Phantom 4 Pro for RGB and (**b**) the DJI Matrice 100 platform with the SlantRange 3p sensor for multispectral data collection.


