Are vegetation indices derived from consumer-grade cameras mounted on UAVs sufficiently reliable for assessing experimental plots?     

《European Journal of Agronomy》2016

Recent technological advances in UAV (unmanned aerial vehicle) technology offer new opportunities for assessing agricultural plot experiments using UAV imagery. Vegetation indices (VIs) based on aerial images derived from consumer-grade cameras are a simple and cheap alternative compared to VIs derived from proximal (on-ground) sensors. The objective of this study was to assess whether VIs derived from consumer-grade cameras mounted on UAVs are reliable and whether there are any shortcomings in image acquisition and analysis that need to be addressed before their general application. This objective was investigated using a rotary-wing and a fixed-wing UAV, true colour (RGB) and colour-infrared (CIR) cameras, four different VIs (ExG, NGRDI, NDVI and ENDVI), altitudes in the range of 30–100 m, different ambient lighting conditions and two different software packages for stitching images together. Results were compared with ground-based recordings by consumer-grade cameras and multispectral sensors. Field experiments in cereals were used to evaluate the assessments. The study showed that VIs based on UAV imagery have the same ability to quantify crop responses to experimental treatments as ground-based recordings with cameras and advanced sensors. However, there are shortcomings that need to be taken into consideration: (1) angular variation in reflectance (bidirectional reflectance), (2) stitching and (3) ambient light fluctuations. Bidirectional reflectance was so extensive that it could lead to misleading conclusions in sunny conditions and this effect could be amplified further by stitching. A procedure for avoiding impacts from bidirectional reflectance is demonstrated when plots were cropped from individual images and a procedure is suggested for stitching images. Camera, VIs and image acquisition altitude were of minor importance, but fluctuating ambient lighting conditions is an issue that should be addressed in future studies.  相似文献   

高动态图像色调映射技术新进展^*     

王作省  邹少芳  王章野 《勤云标准版测试》2011,31(3)

传统显示设备受自身动态范围限制,无法很好显示高动态图像的效果,因此需要用色调映射方法进行合理的动态域压缩,获得更好的图像显示质量。本文综述了现有高动态图像的色调映射技术,首先简要介绍了高动态图像色调映射方法的概念。再介绍了色调映射算子的分类。并以色调映射处理方式为主分别介绍了空域不变算法、空域变化算法及混合算法这三大类算子近年来发展起来的各种新方法,并指出各种方法的技术优势及对此进行了归纳总结。最后阐述了该技术的应用领域及其继续发展的方向。  相似文献   

Fine mapping and conservation analysis of linear B-cell epitopes of peste des petits ruminants virus nucleoprotein     

《Veterinary microbiology》2015,175(1):132-138

Nucleoprotein (NP) is the most abundant and highly immunogenic protein of morbillivirus, and is presently the basis of most diagnostic assays for peste des petits ruminants virus (PPRV). In this study, fine epitope mapping and conservation analysis of linear B-cell epitopes on the PPRV NP has been undertaken using biosynthetic peptides. Nineteen linear B-cell epitopes were identified and their corresponding minimal motifs were located on the NP of PPRV China/Tibet/Geg/07-30. Conservation analysis indicated that ten of the 19 minimal motifs were conserved among 46 PPRV strains. Peptides containing the minimal motifs were recognized using anti-PPRV serum from a goat immunized with PPRV vaccine strain Nigeria 75/1. Identified epitopes and their motifs improve our understanding of the antigenic characteristics of PPRV NP and provide a basis for the development of epitope-based diagnostic assays.  相似文献   

褪黑激素受体1A基因(MTNR1A)的分子遗传学研究进展     

雷梦媛  狄冉  刘秋月  储明星 《农业生物技术学报》2015,23(3):388-396

褪黑激素(melatonin,MEL)是一种重要的内分泌激素,主要由松果体和视网膜分泌,通过与褪黑激素受体(melatonin receptor,MTNR)结合而发生作用,具有广泛的生物学功能。本文主要介绍了褪黑激素受体1A基因(melatonin receptor 1A,MTNR1A)的结构、表达及其在不同物种上克隆、定位、多态性、性状关联分析的研究进展,重点讨论了该基因与季节性繁殖的关系,并对未来MTNR1A基因的研究重点进行了展望,为进一步阐明季节性繁殖机理相关研究提供理论参考。  相似文献   

不同比例尺农田土壤碳库模拟的最佳栅格单元分辨率   总被引：1，自引：0，他引：1  

倪元龙  于东升  张黎明  史学正 《土壤学报》2014,51(1):32-40

基于太湖地区1∶50 000、1∶1 000 000、1∶14 000 000三种比例尺土壤矢量图斑单元以及通过上述矢量图斑单元转换生成的不同分辨率的栅格单元,在1982年水稻土土壤有机碳库的基础上,利用DNDC(Denitrification-Decomposition)模型模拟了2000年水稻土表层(0~20 cm)土壤有机碳库,对比分析了不同分辨率栅格单元与3种比例尺矢量图斑单元的水稻土类型数量、面积、表层土壤有机碳储量以及有机碳密度的变化特征,并以矢量图斑单元获得的这4个指标结果为基准,用相对变异百分数(VIV)来判别基于三种比例尺DNDC模型模拟的最佳栅格单元分辨率。结果表明,在4个指标的│VIV│1%前提下,基于1∶50 000、1∶1 000 000、1∶14 000 000三种比例尺的最佳栅格模拟单元分辨率分别为0.2 km×0.2 km、2 km×2 km、17 km×17 km,既能保证模型模拟过程中的精度要求,又可以避免数据冗余,提高模拟效率。建立的土壤碳库模拟研究的比例尺与其最佳栅格单元分辨率对应转换关系,对区域土壤碳模拟研究具有重要参考价值。  相似文献   

Exploitation of spatial information in high resolution digital imagery to map leaf area index     

C. L. Walthall  Y. Pachepsky  W. P. Dulaney  D. J. Timlin  C. S. T. Daughtry 《Precision Agriculture》2007,8(6):311-321

Crop responses to management practices and the environment, as quantified by leaf area index (LAI), provide decision-making criteria for the delineation of crop management zones. The objective of this work was to investigate whether spatial correlations inferred from remotely sensed imagery can be used to interpolate and map LAI using a relatively small number of ground-based LAI measurements. Airborne imagery was recorded with the Airborne Imaging Spectrometer for Applications (AISA) radiometer over a 3.2 ha corn field. Spectral vegetation indexes (SVI) were derived from the image and aggregated to cells of 2 × 2 m², 4 × 4 m², and 8 × 8 m² resolution. The residual maximum likelihood method was used to estimate the LAI variogram parameters. A generalized least squares regression was used to relate ground truth LAI data and collocated image pixels. This regression result was then used to convert variograms from the imagery to LAI units as well as to interpolate and map LAI. The decrease in resolution by merging pixels led to an increase in the value of the r ² and to a decrease in root mean-squared error (RMSE) values. The accuracy of kriged estimates from the variogram of the measured LAI and that from the image derived variograms was estimated by cross-validation. There was no difference in the accuracy of the estimates using either variograms from measured LAI values or from those of converted SVIs. Maps of LAI from ground-based measurements made by kriging the data with image-derived variogram parameters were similar to those obtained by with kriging with the variogram of measured LAI. Similar coarse spatial trends of high, medium and low LAI were evident for both maps. Variogram parameters from ground-based measurements of LAI compared favorably with those derived from remotely sensed imagery and could be used to provide reasonable results for the interpolation of LAI measurements.  相似文献   

甜瓜作图亲本相关序列扩增的多态性分析     

姚建春 刘玲李唯  王建设 《勤云标准版测试》2006,(7)

以中国甜瓜地方品种自交系4G21(香瓜)和3A832(哈密瓜)为作图亲本,利用SRAP(Se-quence-relatedAmplifiedPolymorphism)分析了甜瓜作图亲本的多态性,结果表明:在184个SRAP引物组合中有176个扩增出多态性条带,不同引物组合扩增的多态性条带的变异幅度在1～15之间,共扩增出614个,平均每个引物组合扩增出3.34个,说明SRAP标记揭示甜瓜作图亲本多态性的效率很高。  相似文献   

2——距离空间中两个膨胀型映射的公共不动点定理     

王桂祥  罗蕴玲 《河北农业大学学报》1997,20(2):103-105

（Ｘ，ｄ）为一完备的２－距离空间，Ａ，Ｂ为两个Ｘ到Ｘ的膨胀型映射，本文的工作是在（Ｘ，ｄ）中讨论了Ａ，Ｂ的公共不动点问题，得到了一个公共不动点定理。  相似文献   

一个水稻雄性不育突变体的遗传分析和基因定位     

初明光  李双成  王世全  邓其明  张婧  丁磊  文勇  郑爱萍  周星宇  李平 《作物学报》1963,35(6):1151-1155

ms-np是一个源于自然突变的水稻雄性不育突变体,明显较正常植株矮小,叶色浓绿。小花解剖观察发现,突变体小花花丝细长,花药干瘪,呈白色透明状,但雄性器官的数量和雌性器官正常。碘染证实,突变体的花药壁内没有花粉粒着色,是一个典型的无花粉型雄性不育材料。5个F₂和2个BC₁F₁群体的遗传分析显示,该突变性状受1对隐性基因控制。对组合ms-np/M63衍生F₂不育单株的连锁分析表明,ms-np(t)基因位于水稻第6 染色体微卫星标记RM541和RM343之间,遗传距离分别为15.2 cM和7.9 cM。  相似文献   

甜瓜作图亲本间分子标记的多态性   总被引：4，自引：1，他引：4  

王建设  孟淑春  宋曙辉  陈贵林  孙振英  李梅 《华北农学报》2002,17(4):5-8

利用DAMD，ISSR和RAPD3种不同类型的分子标记研究了作图亲本栽培甜瓜黄旦子与野生甜瓜PI414723间的多态性，结果表明，DAMD和ISSR揭示作图亲本间多态性的效率较高，而APD标记揭示作图亲本间多态性的效率较低，说明为了提高甜瓜作图效率，除了选择遗传差异相对较大杂交组合外，关键是选择高效揭示多态性的分子标记类型。  相似文献