【摘要】：化肥的過度施用,不僅造成了大量的浪費,提高了農(nóng)業(yè)的生產(chǎn)成本,還造成了大量的環(huán)境污染和水土流失,非常不利于農(nóng)業(yè)的可持續(xù)發(fā)展。為了解決這一問題,就需要進(jìn)入精細(xì)農(nóng)業(yè)的思想,對大田里的農(nóng)作物實現(xiàn)區(qū)別對待,按需施肥。要實現(xiàn)這一目標(biāo)首先必須要實現(xiàn)田間的作物氮素水平快速無損檢測。基于這一需求,本研究開發(fā)出了一種利用機器視覺技術(shù)能夠?qū)μ镩g作物冠層的SPAD值進(jìn)行快速檢測的儀器。具體的研究內(nèi)容和結(jié)論如下:(1)利用作物冠層在近紅外波段的反射率要遠(yuǎn)遠(yuǎn)高于土壤背景在近紅外波段的反射率這一特性,制作了一塊參照板,使得板上參照色塊的近紅外反射率位于土壤和冠層之間。將作物冠層在近紅外波段下的圖像灰度化之后,將參照板的灰度值作為閾值,很好的將作物冠層和土壤背景進(jìn)行了分離。(2)根據(jù)物體的反射率和圖像中表示物體像素的灰度值和獲取圖像時環(huán)境光的強度都成一次線性正相關(guān)關(guān)系這一原理。在參照板上用四種不同的顏色拉開了一個反射率的梯度。并且利用這一梯度建立了反射率和灰度值之間線性模型。成功消除了環(huán)境光對作物冠層反射率計算的影響。(3)利用建立的反射率和灰度值動態(tài)線性模型,通過求出圖像中作物冠層的平均灰度值從而求得了作物冠層在綠色波段和近紅外波段的反射率,進(jìn)而求得作物冠層的GNDVI值。用SPAD-502葉綠素計測量得到的冠層SPAD值。本研究分別對尖椒和茶樹樣本進(jìn)行了取樣,測量了其GNDVI值和冠層SPAD值并進(jìn)行了擬合,得到尖椒冠層的模型為SPAD= 116.72 GNDVI-29.066其決定系數(shù)(R2)為0.8768。茶樹冠層模型為SPAD=88.81GNDVI-11.32其決定系數(shù)(R2)為0.7396。兩者的驗證實驗同樣取得了良好的效果。說明該儀器的測量精度能夠滿足實際農(nóng)業(yè)生產(chǎn)的需求。此外該儀器不僅適用與一種作物,而且有著適用與多種作物的潛能。(4)本研究對尖椒和茶樹樣本進(jìn)行了混合建模,得到的模型為SPAD=104.17GNDVI-20.896其決定系數(shù)(R2)為0.7945。有良好的效果。驗證實驗的結(jié)果也顯示誤差在允許范圍內(nèi)。這說明該儀器有著用一個標(biāo)定模型測量多種作物的潛能。(5)用VB語言為該系統(tǒng)編寫了相應(yīng)的圖像處理軟件,并開發(fā)了相應(yīng)的儀器,能夠很好的實現(xiàn)其功能。
[Abstract]:The excessive application of chemical fertilizer has not only caused a large amount of waste, increased the production cost of agriculture, but also caused a large number of environmental pollution and soil erosion, which is not conducive to the sustainable development of agriculture. In order to solve this problem, it is necessary to enter the idea of fine agriculture, to distinguish the crops in the field and to apply fertilizer as needed. In order to achieve this goal, it is necessary to realize the rapid nondestructive testing of crop nitrogen level in the field. Based on this requirement, a machine vision technique was developed to quickly detect the SPAD of crop canopy in the field. The specific research contents and conclusions are as follows: (1) A reference plate was made by making use of the reflectivity of crop canopy in near infrared band which is much higher than that of soil background in near infrared band. The near infrared reflectance of the reference block is located between the soil and the canopy. After graying the image of crop canopy in near infrared band, the gray value of the reference plate is used as the threshold. The crop canopy is well separated from the soil background. (2) according to the principle that the reflectivity of the object and the gray value of the pixel in the image and the intensity of the ambient light in the image are all linear positive correlation. A gradient of reflectivity is drawn on the reference board with four different colors. The linear model between reflectivity and gray value is established by using this gradient. The effect of environmental light on the calculation of crop canopy reflectivity is successfully eliminated. (3) the dynamic linear model of reflectivity and gray value is used. By calculating the average gray value of crop canopy in the image, the reflectivity of crop canopy in green band and near infrared band is obtained, and the GNDVI value of crop canopy is obtained. The SPAD values of canopy were measured by SPAD-502 chlorophyll meter. In this study, samples of prickly pepper and tea tree were sampled, their GNDVI values and canopy SPAD values were measured and fitted. The model of crown layer of prickly pepper was SPAD= 116.72 GNDVI-29.066 and the determination coefficient (R2) was 0.8768. The model of tea canopy is SPAD=88.81GNDVI-11.32 and the coefficient of determination (R2) is 0.7396. The results of the two experiments are also satisfactory. It shows that the measuring precision of this instrument can meet the demand of actual agricultural production. In addition, the instrument is not only suitable for a single crop, but also has the potential to be suitable for a variety of crops. (4) the mixed modeling of pepper and tea samples was carried out in this study. The model obtained is SPAD=104.17GNDVI-20.896 and its determination coefficient (R2) is 0.7945. Have good effect. The results of the validation experiment also show that the error is within the allowable range. This indicates that the instrument has the potential to measure many crops with a calibration model. (5) the corresponding image processing software is written for the system with VB language and the corresponding instrument is developed, which can achieve its function well.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：S126;TP391.41

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