CAJ | 학술논문

植被冠层二向性反射特征是定量感必须关注的一个问题.论文借助自主研发的多角度成像系统,在不同观测时间对不同种植密度下的大豆冠层进行多角度成像数据采集,通过对“图谱合一”的高光谱影像中大豆植株、土壤背景和影片进行逐步分离,对比分析纯大豆植被与植被-土壤混合冠层的二向反射(Bidirectional Reflectance, BR)变化特征,研究发现:在主平面观测时,土壤光谱去除后,即纯植被冠层反射率在前向观测时,随着天顶角的减小而增大,这不同植被和土壤同时存在时的研究结果(BR随着天顶角的增加而增大);当观测方向由主平面的前向朝后向变动时,可见光和近红外波段的纯植被冠层反射率表现为逐步增大的趋势,这和土壤光谱去除前的变化趋势也不同;在垂直主平面观测时,去除土壤背景后的纯植被冠层反射率与混合植被反射率特征有相同的趋势,但在垂直主平面方向的对称性更强.上述结果在不同密度、不同观测时间的大豆冠层BR特征有相近的趋势,这为多角度感的发展提供了必要的基础研究.
식피관층이향성반사특정시정량감필수관주적일개문제.논문차조자주연발적다각도성상계통,재불동관측시간대불동충식밀도하적대두관층진행다각도성상수거채집,통과대“도보합일”적고광보영상중대두식주、토양배경화영편진행축보분리,대비분석순대두식피여식피-토양혼합관층적이향반사(Bidirectional Reflectance, BR)변화특정,연구발현:재주평면관측시,토양광보거제후,즉순식피관층반사솔재전향관측시,수착천정각적감소이증대,저불동식피화토양동시존재시적연구결과(BR수착천정각적증가이증대);당관측방향유주평면적전향조후향변동시,가견광화근홍외파단적순식피관층반사솔표현위축보증대적추세,저화토양광보거제전적변화추세야불동;재수직주평면관측시,거제토양배경후적순식피관층반사솔여혼합식피반사솔특정유상동적추세,단재수직주평면방향적대칭성경강.상술결과재불동밀도、불동관측시간적대두관층BR특정유상근적추세,저위다각도감적발전제공료필요적기출연구.
Research on bidirectional reflectance characteristics of vegetation canopy is an important direction for quantitative remote sensing. The self-developed multi-angle observation system in this paper was used to collect imaging data of soybean in different sowing density from branch period to flowering period. Characteristics of changes in Bidirectional Reflectance (BR) for pure vegetation and mixed canopy, including vegetation and soil, were analyzed by hyperspectral images from segmenting vegetation, background soil, and shadow leaves. Studies have shown that observation position is the principal plane;canopy reflectanc e of pure vegetation after soil spectra is removed, gradually increased along with the decrease of zenith angle. When forward observation was conducted in principal plane, it differed from the canopy composed of vegetation and soil. When observation direction changed from backward to forward in the principal plane, canopy reflectance of pure vegetation in visible and near-infrared region showed a growing tendency gradually and the soil spectra was removed, this was different from before. In addition, when the observation position was in a perpendicular plane, there was a similar change for reflectance of soybean canopy before and after soil spectra was removed; but the symmetry of canopy reflectance of the former was better than the latter. The results had similar trends with BR change of soybean canopy in different sowing density. The paper provides a basis for the development of multi-angle remote sensing.