摘要
为研究土壤水分的高光谱特征,利用美国ASD公司的FieldSpec 4 HR型地物光谱仪(光谱范围为350~2500nm)测定获取不同含水量土壤样品的高光谱数据,并通过实验分析其水分含量。分别以土壤反射率(R)、反射率的对倒数(Log(1/R))及包络线去除的反射率(Rcr)三个光谱特征进行土壤水分定量反演研究,通过分析各高光谱特征与土壤水分的相关性,遴选特征波段;利用偏最小二乘回归方法(PLSR)建立土壤水分的高光谱定量反演模型,最后利用检验样品进行精度检验和比较。研究结果表明,利用经包络线去除后光谱反射率进行定量反演的预测精度最高,预测值与实测值相关性良好(r^2=0.8983**),趋势线接近于y=x,这为土壤水分的大范围快速监测提供了有效手段。
Hysperspectral characters of soil moisture content was researched in this paper with the FieldSpec 4 HR(wavelength,350~2500 nm)made by ASD Inc..The hyperspectral data of soil with different moisture content were collected,and the soil samples were taken back for experiment analysis.The reflectance of soils(R),the logarithm of the reciprocal of the reflectance(Log(1/R))and the continual removed reflectance(Rcr)were used to research the soil moisture content.The correaltions between the hyperspectral character and soil moisture was studied to filter the characteristics bands.Then the partial least squares regression(PLSR)was used to study the inersion model of soil moisture,and the inversion precision was compared with the verifying samples.The research result showed,the inversion precision with Rcr was the best;the correlation between the predicted value and the measured value was well(r^2=0.898 3**),the trend line was near to y=x,which provides an effective method for monitoring soil moisture.
关键词
偏最小二乘回归
土壤水分
光谱特征
partial least squares regression(PLSR)
soil moisture
spectrum characteristic
