Variability of Reflectance Measurements with Sensor Altitude and Canopy Type
Variability of Reflectance Measurements with Sensor Altitude and Canopy Type
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DOI：
10.2134/agronj1982.00021962007400040034x
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发表时间：
1982-07
期刊：
影响因子：
2.1
通讯作者：
C. Daughtry;V. Vanderbilt;V. J. Pollara
中科院分区：
文献类型：
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作者：
C. Daughtry;V. Vanderbilt;V. J. Pollara
数据采集的树冠成熟玉米种植在76厘米的行，成熟大豆种植在96厘米的行与71%的土壤覆盖，和成熟大豆种植在76厘米的行与100%的土壤覆盖。在树冠上方0.2米至10米的10个高度使用了具有15度视野的大地卫星波段辐射计。在每个海拔高度，测量了15厘米的间隔，也是一个2.0米的横断面垂直于作物行方向。将反射率数据绘制成高度和水平位置的函数，以验证低高度测量值的方差可归因于行效应，该效应在传感器跨几行集成的较高高度处消失。反射率的变化系数随传感器高度的增加呈指数下降。系统采样（在奇数倍的0.5倍的行距间隔）需要较少的测量比简单的随机抽样行作物冠层。
Data were acquired on canopies of mature corn planted in 76 cm rows, mature soybeans planted in 96 cm rows with 71 percent soil cover, and mature soybeans planed in 76 cm rows with 100 percent soil cover. A LANDSAT band radiometer with a 15 degree field of view was used at ten altitudes ranging from 0.2 m to 10 m above the canopy. At each altitude, measurements were taken at 15 cm intervals also a 2.0 m transect perpendicular to the crop row direction. Reflectance data were plotted as a function of altitude and horizontal position to verify that the variance of measurements at low altitudes was attributable to row effects which disappear at higher altitudes where the sensor integrate across several rows. The coefficient of variation of reflectance decreased exponentially as the sensor was elevated. Systematic sampling (at odd multiples of 0.5 times the row spacing interval) required fewer measurements than simple random sampling over row crop canopies.