發(fā)布時間：2018-07-28 19:12

【摘要】：冠層間隙率是在某一天頂角方向一束光穿過冠層而未被攔截的概率。聚集度指數(shù)表征冠層的空間分布集聚情況,描述冠層元素的真實(shí)空間分布與隨機(jī)分布的偏離程度。間隙率和聚集度指數(shù)是兩個重要的冠層結(jié)構(gòu)參數(shù),可用于相關(guān)參數(shù)的反演和校正。地基激光雷達(dá)技術(shù)具有非接觸式、高精度、抗干擾能力強(qiáng)等優(yōu)點(diǎn),能夠?yàn)楣趯咏Y(jié)構(gòu)參數(shù)反演提供有效的技術(shù)支持。本文以電子科技大學(xué)校園內(nèi)的玉蘭樹樣方為研究對象,基于地基激光雷達(dá)數(shù)據(jù),提出了冠層間隙率和聚集度指數(shù)反演的新方法,并實(shí)現(xiàn)了冠層間隙率和聚集度指數(shù)的提取以及冠層聚集情況的研究。此外,本文把數(shù)字半球攝影技術(shù)作為對比手段。主要內(nèi)容和結(jié)論如下:(1)實(shí)驗(yàn)設(shè)計(jì)與數(shù)據(jù)預(yù)處理:基于地基激光雷達(dá)技術(shù)和數(shù)字半球攝影技術(shù),設(shè)計(jì)實(shí)驗(yàn)方案,分別利用Leica ScanStation C10掃描儀和配備魚眼鏡頭的數(shù)碼相機(jī)獲取同一玉蘭樹樣方的三維點(diǎn)云數(shù)據(jù)和數(shù)字半球圖像,并對點(diǎn)云數(shù)據(jù)進(jìn)行配準(zhǔn)、去噪等預(yù)處理,對半球圖像進(jìn)行分類等預(yù)處理。(2)間隙率反演:通過構(gòu)建三維體元模型、轉(zhuǎn)換坐標(biāo)系統(tǒng)、半球面投影等過程,建立基于地面高分辨率激光點(diǎn)云數(shù)據(jù)提取林木冠層間隙率的新方法;基于數(shù)字半球攝影技術(shù),對同一研究對象的數(shù)字半球圖像進(jìn)行冠層間隙率的提取,并將其研究結(jié)果作為對比對象。結(jié)果發(fā)現(xiàn),不同體元大小情況下得到的間隙率與從半球圖像中提取的間隙率在變化趨勢上大致是一致的。當(dāng)討論的天頂角范圍越小時,利用地基激光雷達(dá)數(shù)據(jù)和數(shù)字半球圖像得到的間隙率越接近。對于某一確定的天頂角和方位角,體元越小,間隙率越大,反之亦然。(3)聚集度指數(shù)反演:以玉蘭樹冠層點(diǎn)云數(shù)據(jù)為研究對象,一方面,基于冠層間隙率的對數(shù)平均數(shù)方法進(jìn)行聚集度指數(shù)的反演;另一方面,結(jié)合種群的空間分布型特征,基于SMI(Standardized Morisita's Index)模型研究冠層的聚集情況。基于數(shù)字半球攝影技術(shù),利用數(shù)字半球圖像進(jìn)行了聚集度指數(shù)反演,并將其研究結(jié)果作為對比對象。結(jié)果表明,不同體元大小情況下得到的各天頂角的聚集度指數(shù)與利用半球圖像得到的聚集度指數(shù)在變化趨勢上大致是一致的。對于某一確定的天頂角,體元越小,聚集度指數(shù)越大,反之亦然。研究得到的聚集度指數(shù)均小于1,SMI均大于0,兩個參數(shù)均表明了冠層呈聚集分布。
[Abstract]:The canopy clearance rate is the probability of a beam of light passing through the canopy in the apical direction of a given day without being intercepted. The aggregation index represents the spatial distribution and agglomeration of the canopy and describes the deviation between the real spatial distribution and the random distribution of the canopy elements. Clearance rate and aggregation index are two important parameters of canopy structure, which can be used for inversion and correction of correlation parameters. The ground-based lidar technology has the advantages of non-contact, high precision and strong anti-jamming ability, which can provide effective technical support for the inversion of canopy structure parameters. In this paper, a new method for inversion of canopy clearance rate and aggregation index is proposed based on the ground-based lidar data, taking the sample square of Magnolia in the campus of the University of Electronic Science and Technology as the research object. The extraction of canopy clearance rate and aggregation index and the study of canopy aggregation were also carried out. In addition, digital hemispherical photography is used as a contrast method in this paper. The main contents and conclusions are as follows: (1) Experimental design and data preprocessing: based on ground-based lidar and digital hemispheric photography, the experimental scheme is designed. Leica ScanStation C10 scanner and digital camera equipped with fish-eye lens were used to obtain 3D point cloud data and digital hemispherical image of the same magnolia tree, and the point cloud data were pre-processed, such as registration, denoising and so on. The classification of hemispherical images is preprocessed. (2) clearance rate inversion: a new method for extracting canopy clearance rate based on surface high resolution laser point cloud data is established by constructing 3D volume element model, transforming coordinate system, and semi-spherical projection. Based on digital hemispheric photography, the crown gap rate of the same object was extracted and the results were compared. The results show that the gap rate obtained with different volume size is approximately consistent with the gap rate extracted from hemispherical images. The smaller the range of zenith angle discussed, the closer the gap rate obtained from ground-based lidar data and digital hemispheric image. For a certain zenith angle and azimuth angle, the smaller the volume element, the larger the clearance rate, and vice versa. (3) the inversion of aggregation index: taking the cloud data of magnolia canopy as the research object, on the one hand, Based on the logarithmic average method of canopy gap rate, the aggregation index is inversed. On the other hand, combining the spatial distribution characteristics of the population, the SMI (Standardized Morisita's Index) model is used to study the aggregation of the canopy. Based on digital hemispheric photography, the aggregation index inversion of digital hemispheric images is carried out, and the results are compared. The results show that the aggregation index of the zenith angles obtained with different volume sizes is approximately consistent with that obtained from hemispheric images. For a given zenith angle, the smaller the volume element, the greater the aggregation index, and vice versa. The indexes of aggregation are all less than 1 SMI > 0, and the two parameters indicate that the canopy is clustered.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S758;TN958.98

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