Continuous Monitoring of Visible and Near-Infrared Band Reflectance from a Rice Paddy for Determining Nitrogen Uptake Using Digital Cameras
Continuous Monitoring of Visible and Near-Infrared Band Reflectance from a Rice Paddy for Determining Nitrogen Uptake Using Digital Cameras
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DOI：
10.1626/pps.12.293
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发表时间：
2009-01
影响因子：
2.5
通讯作者：
M. Shibayama;T. Sakamoto;E. Takada;Akihiro Inoue;Kazuhiro Morita;W. Takahashi;A. Kimura
中科院分区：
文献类型：
--
作者：
M. Shibayama;T. Sakamoto;E. Takada;Akihiro Inoue;Kazuhiro Morita;W. Takahashi;A. Kimura
在2007年生长季节，设计了一套双波段数字成像系统，其中一个波段用于可见红光波段(红色，630NIR670 nm)，另一个波段用于近红外波段(−，820NIR900 nm)。在2007年的生长季节，该系统安装在海拔12m的300m2稻田上空。该成像系统每天从−1600时起，每隔10分钟自动记录鸟瞰图像。利用太阳辐射传感器和预先定标对两波段图像进行辐射校正，计算了3个种植密度和3个基肥水平的9块稻田的日波段反射率和归一化差异植被指数(NDVI)值。红光和近红外波段的日平均反射率随植物生长的不同而呈现出不同而平稳的季节变化规律。在最大分蘖数和成穗期，红光和近红外反射率与单位土地面积氮素吸收(NA，gm-2)的相关系数分别为0.79和0.81，而利用这两个波段反射率的NDVI的相关系数为-0.13。使用两个波段反射率值建立的NA经验公式，对于在最大分蘖数和成穗期获得的原始(未验证的)数据集，估计的r值为0.96，误差均方根(RMSE)为0.5gm-2(为观测平均值的10%)。结果表明，利用数字成像系统对红光和近红外波段的反射率进行观测，可以有效地评估水稻的生长状况。
Abstract A two-band digital imaging system —one band for the visible red band (RED, 630−670 nm) and the other for the near infrared band (NIR, 820−900 nm)— was devised and positioned at a height of 12 m above a rice field of 300 m2 in area during the 2007 growing season. The imaging system automatically logged bird’seye view images at 10-min intervals from 0800−1600 every day. Radiometric corrections for the pairs of two-band images were done using solar irradiance sensors and preceding calibrations to calculate daily band-reflectance and the normalized difference vegetation index (NDVI) values for 9 plots of rice plants, with 3 levels of planting density and basal fertilization. The daily- averaged reflectance values in the RED and the NIR bands showed different but smooth seasonal changing patterns according to the growth of plants. At the maximum tiller number and the panicle formation stages, the RED and NIR reflectance values had correlation coefficients (r) of 0.79 and 0.81 with above-ground nitrogen absorption per unit land area (NA, g m-2), respectively, whereas the NDVI using the two band reflectance values showed r-value of -0.13. An empirically derived equation for the NA using two band reflectance values showed r-value of 0.96 and a root mean square of error (RMSE) 0.5 g m–2 (10% of the mean observed NA) in the estimation for the original (not validated) data set acquired at the maximum tiller number and the panicle formation stages. The results indicated that reflectance observation in the RED and NIR bands using the digital imaging system was potentially effective for assessing rice growth.