基于真实三维结构的玉米冠层生化参数垂直分布的定量化分析

为了定量研究作物生化参数在冠层中的垂直分布情况,本文以2000年栾城实验测量的玉米冠层自上而下不同叶位叶片的光谱数据为基础,利用PROSPECT模型进行反演,获得每层叶片的叶绿素(a b)含量、等效水厚度、干物质含量等叶片的生化参数.通过比较发现:玉米冠层叶绿素等含量生化参数具有明显的随高度垂直分层现象,最明显的就是叶片的叶绿素含量,最大和最小叶绿素含量的相对差值甚至可以达到最大值的79.1%.在此基础上,根据实测玉米冠层结构,利用扩展L系统生成玉米真实三维结构冠层场景.通过统计计算每层叶片的生化参数,进而得到冠层生化参数的垂直分布.这为进一步基于冠层光谱的参数反演和定量分析以及农业应用等研究奠定了理论基础.

ANALYSIS ON THE VERTICAL DISTRIBUTION OF BIOCHEMICAL PARAMETERS BASED ON A 3D VIRTUAL CORN CANOPY SCENE

To study the vertical distribution of biochemical parameters of crops quantitatively,summer corn is taken for an example.At first,the spectra of each leaf from top to bottom of corn canopy are measured in the summer of 2000 at Luancheng,Hebei province,China.Then the biochemical parameters of each leaf,including chlorophyll a b,water contents and biomass contents,are inverted by using PROSPECT model.It is found that all biochemical parameters are obviously different with different leaf,and as the largest one,the relative difference of chlorophyll a b between each leaf is 79.1% according the inverted results.In addition,the corn canopy structural parameters are measured,and then a virtual 3D corn scene is rebuilt by extended L system.Finally,the vertical distribution of biochemical parameters can be calculated based on the 3D scene,which is much more accurate with more divided layers.Therefore,this method can be applied to analyze crop situations and establish the relationship between the spectra of crop canopy and the vertical biochemical parameters in the future.