重金属铅离子胁迫下玉米叶片光谱弱差信息的 DSAT 甄别模型

摘要

光谱间微弱信息测度是当今高光谱遥感研究难点之一,传统光谱测度方法难以区分光谱信息的微弱差异。研究设计了不同浓度的铅(Pb)污染实验,并测量了不同浓度铅离子(Pb2+)胁迫下玉米叶片的高光谱反射率、叶绿素含量及 Pb2+含量,但是从所测结果得出,不同浓度 Pb2+胁迫下的光谱相似性相关系数均达到0.999,难以区分不同浓度 Pb2+胁迫引发的光谱间微弱信息差异和污染程度。针对这一情况,基于光谱微分处理、正切函数增强、光谱角量度与波谱分段检测等,提出了一种新型的相似光谱测度方法,即微分光谱角正切(derivative spectral angle tangent,DSAT)法。为了验证 DSAT 在区分相关系数达0.99以上相似光谱的可行性和有效性,将 DSAT 用于不同浓度 Pb2+胁迫玉米叶片的整体波形与光谱区间子波形的信息差异性度量与检测。实验结果得到,波形差异信息与玉米叶片中叶绿素相对浓度与 Pb2+含量显著相关。进而也证明 DSAT 法在甄别较高相似性光谱间差异上具有更好的实用性和优越性。%Weak information measurement between the spectra is one of the toughest current research issues in the hyperspectral remote sensing domainTraditional measuring methods are difficult to distinguish the weak information differences.The experi-ment on the lead(Pb)pollution was designed based on its different concentrations,meanwhile,the hyperspectral reflectance, chlorophyll and lead ion(Pb2+ )contents of corn leaves stressed by different Pb2+ concentrations were measured.However,it is difficult to distinguish the differences on weak information between the spectra and the pollution levels of corn leaves stressed by different Pb2+ concentrations because the spectral correlation coefficients have reached 0.999 according to the measured results. Due to this fact,a novel spectral similarity measuring method that is the derivative spectral angle tangent (DSAT)model,was put forward based on the spectral derivative processing,tangent function enhancement,spectral angle measurement,piecewise spectral detection and so on.In order to verify the feasibility and effectiveness of DSAT in distinguishing the differences of the similar spectra that their correlation coefficients reach 0.99,the DSAT was used to measure the weak information differences be-tween the spectra of corn leaves stressed by different Pb2+ concentrations by the ways on detecting the whole waveforms and the sub-interval waveforms of corn leaf spectra.The experimental results showed that the relative chlorophyll concentration and Pb2+ contents of corn leaves were significantly correlated with the waveform difference information.It also proves that the DSAT model has better practicability and superiority in distinguishing the difference between the high similarity spectra.