资源描述：
《基于SAILH模型的植被冠层NDVI二向性分析》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。
1、遥感信息理论研究2011.1基于SAILH模型的植被冠层NDVI二向性分析,,,,梁守真,施平,周迪(中国科学院烟台海岸带研究所,烟台264003;中国科学院南海海洋研究所,广州510301;中国科学院研究生院,北京100049)摘要:NDVI是植被遥感中最为常用的一种植被指数,建立NDVI与其他冠层参数模型必须考虑其方向性问题。本文基于SAILH模型讨论了连续植被冠层NDVI的二向性特征,并分析了叶面积指数、叶倾角分布、热点参
2、数以及太阳天顶角和相对方位角对NDVI的影响。研究表明冠层NDVI在主平面观测方向存在一个明显的负热点,前向散射方向的NDVI大于后向散射方向;冠层NDVI的二向性分布随外界参数的改变而发生变化,但每个参数对NDVI二向性的影响程度不同,并且通常后向散射方向受各参数的影响要小于前向散射方向。关键词:NDVI;SAILH模型;热点效应;二向性doi:10.3969/j.issn.1000-3177.2011.01.004中图分类号:TP79文献标识码:A文章编号:1000-3177(2011)113-0022-05Anal
3、ysisofNDVIBidirectionalityBasedonSAILHModelLIANGShouzhen,,,SHIPing,ZHOUDi,,(YantaiInstituteofCoastalZoneResearch,ChineseAcademyofSciences,Yantai264003;SouthChinaSeaInstituteofOceanology,ChineseAcademyofSciences,Guangzhou510301;GraduateUniversityofChineseAc
4、ademyofSciences,Beijing100039)Abstract:NDVI(NormalizedDifferenceVegetationIndex)isanimportantvegetationindex,extensivelyusedtoindicatevegetationstatus.Butduetoitsanisotropyorbidirectionality,therearemanylimitationswhentodevelopthemodelbetweenNDVIandvegetationparamete
5、rsandtheprecisionofmodelislow.Inordertodevelopreliablemodel,itisnecessarytoknowaboutthebidirectionalityofNDVI.SAILHmodelcanmodelBRDFofvegetationcanopy,sobasedontheBRDFofcanopythebidirectionaldistributionofNDVIcanbecalculated.TheresultshowsthatNDVIhasveryobviousbidi
6、rectionalityoranisotropyanditcanbeinfluencedbydifferentparameterssuchasLAI(LeafAreaIndex),LAD(LeafAngleDistribution),hotparameter,solarzenithandrelativeazimuth.ThedifferencebetweenbidirectionaldistributionofNDVIandBRDFisthatNDVIhasthesmallestvalueinthehotspot,butcano
7、pyBRDFiscontrary.Intheprincipalplane,thevalueofNDVIinforwardscatteringdirectionislargerthaninbackwardscatteringdirection.WiththeincreaseofLAI,theNDVIincreases,butsaturationoccurs.WhenLAIisconstant,otherparameterscanchangethevalueandangledistributionofNDVI.Becausethe
8、hotspoteffectonlyoccurswhenobserverisintheprincipalplane,bidirectionalityofNDVIwillweakeninotherplanes.Theincreaseofsolarzenithmake
