Measurement Method for Height-Independent Vegetation Indices Based on an Active Light Source

Sensors

卷:20

Xueni Wu¹  Yongqian Ding¹  Chuanlei Yang¹  Yizhuo Jiang¹  Guoxiang Sun¹  Xiuqing Fu¹  Hongfeng Yu¹  Xianglin Dou¹ 

[1] College of Engineering, Nanjing Agricultural University, Nanjing 210031, China;

关键词: active light source;    vegetation indices;    reflectance spectrometer;    measurement method;   

DOI  :  10.3390/s20071830

来源: DOAJ

【 摘 要 】

A coefficient C_W, which was defined as the ratio of NIR (near infrared) to the red reflected spectral response of the spectrometer, with a standard whiteboard as the measuring object, was introduced to establish a method for calculating height-independent vegetation indices (VIs). Two criteria for designing the spectrometer based on an active light source were proposed to keep C_W constant. A designed spectrometer, which was equipped with an active light source, adopting 730 and 810 nm as the central wavelength of detection wavebands, was used to test the Normalized Difference Vegetation Index (NDVI) and Ratio Vegetation Index (RVI) in wheat fields with two nitrogen application rate levels (NARLs). Twenty test points were selected in each kind of field. Five measuring heights (65, 75, 85, 95, and 105 cm) were set for each test point. The mean and standard deviation of the coefficient of variation (CV) for NDVI in each test point were 3.85% and 1.39% respectively, the corresponding results for RVI were 2.93% and 1.09%. ANOVA showed the measured VIs possessed a significant ability to discriminate the NARLs and had no obvious correlation with the measurement heights. The experimental results verified the feasibility and validity of the method for measuring height-independent VIs.

【 授权许可】

Unknown