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Improving the estimation of canopy cover from UAV-LiDAR data using a pit-free CHM-based method

International Journal of Digital Earth 2021年第10期14卷 1477-1492页

作者： Shangshu Cai Wuming Zhang Shuangna Jin Jie Shao Linyuan Li Sisi Yu Guangjian Yan School of Geospatial Engineering and Science Sun Yat-Sen UniversityZhuhaiPeople’s Republic of China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) GuangdongPeople’s Republic of China State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and Institute of Remote Sensing and Digital Earth of Chinese Academy of SciencesBeijingPeople’s Republic of China Beijing Engineering Research Center for Global Land Remote Sensing Products Institute of Remote Sensing Science and EngineeringFaculty of Geographical ScienceBeijing Normal UniversityBeijingPeople’s Republic of China The Key Laboratory for Silviculture and Conservation of Ministry of Education Beijing Forestry UniversityBeijingPeople’s Republic of China Aerospace Information Research Institute Chinese Academy of SciencesBeijingPeople’s Republic of China

Accurate and rapid estimation of canopy cover(CC)is crucial for many ecological and environmental models and for forest *** aerial vehicle-light detecting and ranging(UAV-LiDAR)systems represent a promising tool for CC estimation due to their high mobility,low cost,and high point ***,the CC values from UAV-LiDAR point clouds may be underestimated due to the presence of large quantities of within-crown *** alleviate the negative effects of within-crown gaps,we proposed a pit-free CHM-based method for estimating CC,in which a cloth simulation method was used to fill the within-crown *** evaluate the effect of CC values and withincrown gap proportions on the proposed method,the performance of the proposed method was tested on 18 samples with different CC values(40−70%)and 6 samples with different within-crown gap proportions(10−60%).The results showed that the CC accuracy of the proposed method was higher than that of the method without filling within-crown gaps(R^(2)=0.99 vs 0.98;RMSE=1.49%vs 2.2%).The proposed method was insensitive to within-crown gap proportions,although the CC accuracy decreased slightly with the increase in withincrown gap proportions.

关键词： canopy cover light detecting and ranging unmanned aerial vehicle within-crown gaps pit-free CHM 1.

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Quality Assessment of River Offin along a canopy cover Gradient

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Journal of Water Resource and Protection 2016年第3期8卷 337-344页

作者： Janice Dwomoh Abraham Isaac Fosu Daniel Agyapong Kwame Nkrumah Hope John Abraham Department of Science Education College of Agriculture Education University of Education Winneba Ghana Department of Crop and Soil Sciences Education College of Agriculture Education University of Education Winneba Ghana Department of Entomology and Wildlife School of Biological Sciences University of Cape Coast Cape Coast Ghana

The potential effect of canopy cover on the quality of River Offin which serves as drinking water for communities including Hwediem, Mprim and Boanim in the Mampong Municipality of the Ashanti region of Ghana was studied. These communities exemplify Ghanaian farming communities. Often, rural farmers do not have access to clean water. Using the part of the river serving these communities as a test case, we assessed the quality of water along a gradient of three different levels of canopy cover (closed, semi-closed and open canopy) where residents frequently access water. Physico-chemical tests showed that, the level of most of the physical and chemical properties of the water under all three different canopy covers was within the acceptable limits set by the World Health Organization. There was low turbidity where the canopy was closed resulting in relatively lower faecal coliforms. Total dissolved solids were also less where canopy cover was closed. Therefore, the general water quality could be potentially improved by planting trees along the river to form canopy.

关键词： Water Quality Watershed Farming Runoff Water canopy cover

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Estimating oak forest parameters in the western mountains of Iran using satellite-based vegetation indices

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Journal of Forestry Research 2020年第2期31卷 541-552页

作者： Adel Nouri Bahman Kiani Mohammad Hossein Hakimi Mohammad Hossein Mokhtari Department of Forest Sciences Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran Department of Desert Management Faculty of Natural ResourcesYazd UniversityYazdIslamic Republic of Iran

Remote sensing is an important tool for studying and modeling forest *** indices obtained from Landsat-8 remotely sensed data were used to estimate the forest parameters in the western mountains of *** sample points were selected on the map of Bayangan County,Kermanshah province,*** each point,a cluster of five rectangular plots of 8100 m2 and 200 m apart was *** clusters were primarily sampled to determine the variance of the forest *** coefficient of variation was used as a criterion for sample *** density,canopy cover and basal area per hectare were calculated for each *** indices were extracted fromthe Landsat-8 images for each *** linear and nonlinear regressions were conducted to develop the *** models were validated using an independent data *** of model parameters was statistically *** results showed that Normalized difference vegetation index(NDVI)and Transformed normalized difference vegetation index(TNDVI)followed by Simple ratio vegetation index(SRVI)were the best predictors,explaining up to 91%of the variations with high *** NDVI,Soil adjusted vegetation index 2(SAVI2)and SRVI,the cubic model was more appropriate than the linear model for predicting the forest *** this model,the R-square value increased while NRMSE decreased *** Infrared percentage vegetation index(IPVI),the quadratic model was better,but,for other vegetation indices,nonlinear models were not superior to linear ***,it can be concluded that Landsat-8 imagery is suitable for predicting forest parameters in the oak forests of western *** course,large plots must be selected,and pre-classification is necessary to gain accurate and precise estimations.

关键词： Basal area canopy cover Density Landsat-8 Modeling

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Digital surface model applied to unmanned aerial vehicle based photogrammetry to assess potential biotic or abiotic effects on grapevine canopies

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International Journal of Agricultural and Biological Engineering 2016年第6期9卷 119-130页

作者： Su Baofeng Xue Jinru Xie Chunyu Fang Yulin Song Yuyang Sigfredo Fuentes College of Mechanical and Electronic Engineering Northwest A&F UniversityYangling 712100China College of Enology Northwest A&F UniversityYangling 712100China Faculty of Veterinary and Agricultural Sciences University of MelbourneParkville 3010Australia

Accurate data acquisition and analysis to obtain crop canopy information are critical steps to understand plant growth dynamics and to assess the potential impacts of biotic or abiotic stresses on plant development.A versatile and easy to use monitoring system will allow researchers and growers to improve the follow-up management strategies within farms once potential problems have been *** study reviewed existing remote sensing platforms and relevant information applied to crops and specifically grapevines to equip a simple Unmanned Aerial Vehicle(UAV)using a visible high definition RGB *** objective of the proposed Unmanned Aerial System(UAS)was to implement a Digital Surface Model(DSM)in order to obtain accurate information about the affected or missing grapevines that can be attributed to potential biotic or abiotic stress *** analysis process started with a three-dimensional(3D)reconstruction from the RGB images collected from grapevines using the UAS and the Structure from Motion(SfM)technique to obtain the DSM applied on a per-plant ***,the DSM was expressed as greyscale images according to the halftone technique to finally extract the information of affected and missing grapevines using computer vision algorithms based on canopy cover measurement and *** validate the automated method proposed,each grapevine row was visually inspected within the study *** inspection was then compared to the digital assessment using the proposed UAS in order to validate calculations of affected and missing grapevines for the whole studied *** showed that the percentage of affected and missing grapevines was 9.5%and 7.3%,respectively from the area ***,for this specific study,the abiotic stress that affected the experimental vineyard(frost)impacted a total of 16.8%of *** study provided a new method for automatically surveying affected or missing grapevines in the field and an evaluation tool fo

关键词： remote sensing canopy cover viticultural management frost damage digital surface model

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High resolution aerial photogrammetry based 3D mapping of fruit crop canopies for precision inputs management

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Information Processing in Agriculture 2022年第1期9卷 11-23页

作者： Rajeev Sinha Juan J.Quiros Sindhuja Sankaran Lav R.Khot Department of Biological Systems Engineering Center for Precision and Automated Agricultural SystemsWashington State UniversityProsserWA 99350United States

Rapid and accurate canopy attributes estimation is highly critical in fruit crops production management as this information can be used for canopy and crop load management as well as to develop nutrient/chemical prescription application ***,the existing ground based canopy sensing and attribute estimation methods are laborious and often involve complexity with field data collection and *** methods can be subjec-tive as ***,this study explores aerial photogrammetry based method of tree–row–volume(TRV),leaf–wall–area(LWA),canopy volume(CV)and canopy cover(CC)esti-mation for grapevine and apple *** sensing data was collected using a con-sumer–grade small unmanned aerial system(UAS)with an RGB imaging sensor flying at different flight altitudes i.e.,15 m(Ground sampling distance,GSD=0.45 cm pixel^(-1) at 65°sensor inclination),30 m(0.90 and 0.85 cm pixel^(-1) at 65°and 75°,respectively),45 m(1.35 and 1.27 cm pixel^(-1) at 65°and 75°,respectively)and 60 m(1.81 and 1.69 cm pixel^(-1) at 65°and 75°,respectively).Crop surface model(CSM)was derived from such data to esti-mate canopy height,width and foliage vigor,which are further used to estimate TRV,LWA,CV and *** ground measured and aerial imagery estimated TRV had a strong relation-ship with the data collected at the lowest GSD within grapevine canopies(R^(2)=0.77 at 0.45 cm pixel^(-1)as well as for apple canopies(R^(2)=0.82 at 0.90 cm pixel^(-1).Similar trends were observed for the LWA(R^(2)=0.77 and 0.86),CV(R^(2)=0.43 and 0.64)and CC(R^(2)=0.61 and 0.68)estimates for grapevine and apple canopies,*** GSD(≥0.45 cm pixel^(-1) in grapevine and≥0.90 cm pixel^(-1) in apple)resulted in a weak relationship between ground measurements and aerial imagery data-based estimates for grapevines(R^(2)=0.36)and apple canopies(R^(2)=0.39–0.78).Overall,the aerial flights with lower GSD and double grid missions with RGB imaging sensor in 65°orientation aided in the develo

关键词： Unmanned aerial system Photogrammetry Tree-row-volume Leaf-wall-area canopy cover Prescription maps

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Seed germination and seedling establishment of Neotropical dry forest species in response to temperature and light conditions

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Journal of Forestry Research 2009年第A2期20卷 99-104,I0001页

作者： Benigno Gonzalez-Rivas Mulualem Tigabu Guillermo Castro-Marin Per Christer Oden Facultad de Recursos Naturales y del Ambiente. Universidad Nacional Agraria. Managua Nicaragua. Apartado Postal 453 Swedish University of Agricultural Sciences Southern Swedish Forest Research Centre PO Box 101 SE-230 53Alnarp Sweden

A study was conducted to examine the germination requirements of Cedrela odorata, Guaiacum sanctum and Calycophyllum candidissimum seeds, and the effect of light intensity on survival and growth of C. odorata and G. sanctum seedlings planted on open, partially-open and beneath the canopy of a dry forest in Nicaragua. The results show that germination of C. candidissimum seeds was signifi- cantly higher in light than darkness at constant temperatures ranging from 20-35℃. Both C. odorata and G. sanctum seeds germinated in light and darkness to a varying extent, and the optimal germination temperature was around 20-25℃. Alternating temperature regimes did not improve germination. Survival of G. sanctum seedlings was 70% beneath the canopy and 80% in the open, and its relative growth rate in collar diameter was 1.88 mm/month in the open and 1.42 mm/month in the understory. Survival was generally poor for C. odorata, particularly in the understory. We concluded that light is an absolute requirement for the germination of C. candidissimum seeds while germination of C. odorata and G. sanctum seeds are more sensitive to temperature. Owing to its high survival rate on open site, G. sanctum could serve as a candidate species for reforestation of degraded sites.

关键词： canopy cover seed germination Nicaragua photoblastic seed survival rate restoration Cedrela odorata Guaiacum sanctum Calycophyllum candidissimum

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Estimation of Maize Growth and Nitrogen Nutrition Status Using Color digital Camera Image Analysis

Estimation of Maize Growth and Nitrogen Nutrition Status Usi...

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2014年全国青年作物栽培与生理学术研讨会

作者： Tao Zhi-qiang Li Cong-feng Ma Wei Shamim Ara Bagum Sun Xue-fang Zhao Ming Institute of Crop Sciences Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and EcologyMinistry of Agriculture

[Introduction]canopy cover(CC) is a good predictor variable for plant growth parameters such as leaf area index and aboveground biomass.A nondestructive,low-cost,and convenient method is presented for estimating CC using digital camera image *** was estimated by the ratio of plant pixels to total pixels of digital camera image of maize *** objective of the present study was to construct a non-destructive method for monitoring maize growth and nitrogen(N) nutrition status with digital camera image analysis.[Materials and Methods]Digital images of maize canopies grown with cultivars(Zhongdan 909) under various nitrogen treatments were captured by a digital camera periodically before V12 and at the same time maize plants were sampled to measure LAI,shoot dry weight,and shoot N accumulation in 2014 at Agricultural Experimental Site of Scientific Observation Station of Ecological and Environment,at Langfang *** and ten color indices were calculated from digital camera images using Maize CC Image Analysing System developed in Visual Basic version 6.0(Institute of Crop Sciences,Chinese Academy of Agricultural Sciences 2013).[Result and Analysis]More than eight color indices and CC showed significant correlations with growth and N nutrition parameters like LAI,shoot dry weight,and shoot N *** revealed the highest correlations with all of ***(variables) expressed a curve-linear relationship with LAI,shoot dry weight and shoot N accumulation(dependent variable) being well fitted to a exponential function:y=*** statistically different relationships of CC with parameters a and b were found among N fertilization levels as a values decrease and b values increase with the increase of N fertilization *** compensate the effects of N level,stepwise multiple linear regression(SMLR) models including nonlinear relationship of CC and color indices were calibrated and *** selected SMLR models for LAI,shoot dry weight,and shoot N accumula

关键词： spring maize digital camera canopy cover LAI shoot dry weigh shoot N accumulation

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Effects of environmental factors on species richness patterns of herb layer in Eastern Zhongtiao Mountain

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Journal of Forestry Research 2005年第3期16卷 175-180页

作者： LIU Qiu-feng KANG Mu-yi WANG Hao LIU Quan-ru Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education of China College of Resources Science ＆ Technology BeiJing Normal University Beijing 100875 P. R. China National Climate Center Beijing 100081 P. R. China

The species richness of herb layer was investigated among 43 plots of forest vegetation in the eastern Zhongtiao Mountain, in southern Shanxi Province, China. The forest vegetation was divided into two major vegetation types such as the deciduous forest and the coniferous forest by the two-way indicator species analysis （TWINSPAN）. The species richness of herb layer was fitted in the topographic and soil feature factors, as well as the topographic relative moisture index （TRMI） by the generalized linear models （GLM）. The results showed that canopy cover and altitude were the most significant environmental factors. Soil pH value and soil nutrients index such as total N, organic matter content had no significant influence. The effect of environment factors on species richness of herb layer had significant difference in vegetation types. For the broad-leaved forest, litter depth and TRMI were the important environment factors. For the coniferous forest, soil clay content was another important environment factor. The range of environmental gradient such as altitude may contribute to the difference.

关键词： Eastern Zhongtiao Mountain Altitude canopy cover Broad-leaved and Coniferous forests GLM Soil nutrients

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