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Готові списки джерел за темами / Hemispherical photograph / Статті в журналах

Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Hemispherical photograph.

Статті в журналах з теми "Hemispherical photograph"

Автор: Grafiati

Опубліковано: 3 червня 2025

Оновлено: 31 липня 2025

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1

Machado, José-Luis, and Peter B. Reich. "Evaluation of several measures of canopy openness as predictors of photosynthetic photon flux density in deeply shaded conifer-dominated forest understory." Canadian Journal of Forest Research 29, no. 9 (1999): 1438–44. http://dx.doi.org/10.1139/x99-102.

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The ability to accurately estimate light levels in shaded environments is important for understanding plant adaptations to shade. This study evaluates the effectiveness of three rapid methods of estimating the long-term integrated percentage of above-canopy photosynthetic photon flux density (PPFD) in a deeply shaded conifer-dominated forest understory. These methods included (i) hemispherical canopy photography, (ii) hemispherical sensors (LAI-2000), and (iii) instantaneous %PPFD. Transmitted PPFD was continuously measured starting in June and ending in November using photodiodes at 60 measur

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2

Ghazali, Mochamad Firman. "MAPPING THE AIR MOISTURE CHANGE IN UNDER CANOPY TREES USING A HEMISPHERICAL AND AERIAL PHOTOGRAPH BASED ON MACHINE LEARNING APPROACHES." International Journal of Remote Sensing and Earth Sciences (IJReSES) 19, no. 2 (2023): 153. http://dx.doi.org/10.30536/j.ijreses.2022.v19.a3816.

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The essential roles of trees in controlling the local climatic variation, such as air moisture, are still interesting to observe. Therefore, this study must deliver knowledge of the benefits of growing trees and enhance people's awareness of climate change adaptation. Here, the analysis requires several data fields such as hemispherical photography, an aerial photograph of a UAV, and air temperature collected using a wet and dry bulb thermometer, which has converted to air moisture. All these are considered to understand the air moisture change under the trees' canopy during a day observation.

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3

Umarhadi, Deha Agus, and Projo Danoedoro. "Comparing canopy density measurement from UAV and hemispherical photography: an evaluation for medium resolution of remote sensing-based mapping." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 1 (2021): 356. http://dx.doi.org/10.11591/ijece.v11i1.pp356-364.

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UAV and hemispherical photography are common methods used in canopy density measurement. These two methods have opposite viewing angles where hemispherical photography measures canopy density upwardly, while UAV captures images downwardly. This study aims to analyze and compare both methods to be used as the input data for canopy density estimation when linked with a lower spatial resolution of remote sensing data i.e. Landsat image. We correlated the field data of canopy density with vegetation indices (NDVI, MSAVI, and AFRI) from Landsat-8. The canopy density values measured from UAV and hem

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4

Deha, Agus Umarhadi, and Danoedoro Projo. "Comparing canopy density measurement from UAV and hemispherical photography: an evaluation for medium resolution of remote sensing-based mapping." International Journal of Electrical and Computer Engineering (IJECE) 11, no. 1 (2021): 356–64. https://doi.org/10.11591/ijece.v11i1.pp356-364.

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UAV and hemispherical photography are common methods used in canopy density measurement. These two methods have opposite viewing angles where hemispherical photography measures canopy density upwardly, while UAV captures images downwardly. This study aims to analyze and compare both methods to be used as the input data for canopy density estimation when linked with a lower spatial resolution of remote sensing data i.e. Landsat image. We correlated the field data of canopy density with vegetation indices (NDVI, MSAVI, and AFRI) from Landsat-8. The canopy density values measured from UAV and hem

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5

Zhao, Kangning, and Fangliang He. "Estimating light environment in forests with a new thresholding method for hemispherical photography." Canadian Journal of Forest Research 46, no. 9 (2016): 1103–10. http://dx.doi.org/10.1139/cjfr-2016-0003.

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Light environment estimates derived from hemispherical photography are known to be affected by variations in sky illumination. During photo acquisition, rapid changes in sky illumination can occur and will result in changes in detected canopy gap size and frequency. Any resulting problems in image consistency will become more serious with increased time lags between setting the reference exposure and hemispherical photograph acquisition. We showed that if the camera exposure setting was kept constant during photo acquisition, the estimated diffuse transmittance would be greatly influenced by s

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6

Yun, Ting, Weizheng Li, Yuan Sun, and Lianfeng Xue. "Study of Subtropical Forestry Index Retrieval Using Terrestrial Laser Scanning and Hemispherical Photography." Mathematical Problems in Engineering 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/206108.

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In order to retrieve gap fraction, leaf inclination angle, and leaf area index (LAI) of subtropical forestry canopy, here we acquired forestry detailed information by means of hemispherical photography, terrestrial laser scanning, and LAI-2200 plant canopy analyzer. Meanwhile, we presented a series of image processing and computer graphics algorithms that include image and point cloud data (PCD) segmentation methods for branch and leaf classification and PCD features, such as normal vector, tangent plane extraction, and hemispherical projection method for PCD coordinate transformation. In addi

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7

Adinugroho, Wahyu Catur, Lilik Budi Prasetyo, Cecep Kusmana, and Haruni Krisnawati. "Spatial-temporal forest canopy density in Indonesia’s new capital city and its surrounding area." IOP Conference Series: Earth and Environmental Science 1266, no. 1 (2023): 012001. http://dx.doi.org/10.1088/1755-1315/1266/1/012001.

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Abstract Monitoring the condition of the forest in Indonesia’s New Capital City, Nusantara (IKN), and the surrounding area as a buffer is crucial to realizing the Forest City concept. Forest canopy density can be used to understand and measure forest conditions using satellite imagery efficiently. The main objective of this study was to investigate the spatial-temporal dynamic alterations of forest canopy density across IKN and its buffer. Forest canopy density is based on Landsat 8 imagery for 2015-2020, processed in the cloud using the Google Earth Engine (GEE) and compared using a hemispher

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8

Nurdiansah, Doni, and I. Wayan Eka Dharmawan. "Komunitas Mangrove di Wilayah Pesisir Pulau Tidore dan Sekitarnya." Oseanologi dan Limnologi di Indonesia 3, no. 1 (2018): 1. http://dx.doi.org/10.14203/oldi.2018.v3i1.63.

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<strong>Mangrove Community in Coastal Area of Tidore Islands.</strong> Indonesia has the most extensive area of mangrove ecosystem in the world. It bring many direct and indirect benefits for the coastal community. Research on the condition of mangrove communities in Tidore, Halmahera, Ternate Island and surrounding areas was conducted in August 2015, to determine the current condition of mangrove communities in the region. Assessment condition mangrove forest was done by means of analyze the percentage covering canopy with the hemispherical photography methods (photography t

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9

HU, Ning, Chuan-Gen LÜ, Ke-Min YAO, and Xiao-Cui ZHANG. "Inversion of Rice Canopy Construction Parameters from the Hemispherical Photograph." Acta Agronomica Sinica 40, no. 8 (2014): 1443. http://dx.doi.org/10.3724/sp.j.1006.2014.01443.

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10

Zhang, Yongqin, Jing M. Chen, and John R. Miller. "Determining digital hemispherical photograph exposure for leaf area index estimation." Agricultural and Forest Meteorology 133, no. 1-4 (2005): 166–81. http://dx.doi.org/10.1016/j.agrformet.2005.09.009.

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11

Wang, Y. S., and D. R. Miller. "Calibration of the Hemispherical Photographic Technique to Measure Leaf Area Index Distributions in Hardwood Forests." Forest Science 33, no. 1 (1987): 210–16. http://dx.doi.org/10.1093/forestscience/33.1.210.

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Abstract Measured distributions of leaf inclination angles and leaf azimuth angles from one stand of red maple (Acer rubrum L.) are used to modify hemispherical photograph determinations of leaf area index in two other plots of red maple as well as in the stand where structure measurements were made. LAI determinations by this technique were within 3.5% of leaf weighting measurements and 5.8% of LAI measurements by a point drop technique. This is approximately twice the accuracy of the photograph technique without calibration. For. Sci. 33(1):210-216.

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12

Hu, Lile, Zhiwen Gong, Junsheng Li, and Jiaojun Zhu. "Estimation of canopy gap size and gap shape using a hemispherical photograph." Trees 23, no. 5 (2009): 1101–8. http://dx.doi.org/10.1007/s00468-009-0353-9.

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13

Mutiara, Basuki Tyas. "LEAF AREA INDEX DERIVED FROM HEMISPHERICAL PHOTOGRAPH AND ITS CORRELATION WITH ABOVEGROUND FOREST BIOMASS." JOURNAL OF FORESTRY RESEARCH 2, no. 1 (2015): 31–41. https://doi.org/10.20886/ijfr.2015.2.1.31-41.

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Leaf  area index (LAI) is one of  the key physical factors in the energy exchange between terrestrial ecosystem and atmosphere. It determines the photosynthesis process to produce biomass and plays an important role in performing forest stand reflectance. Therefore building relationship between LAI and biomass from field measurements can be used to develop allometric equations for biomass estimation. This paper studies the relationship between diameter at breast height (DBH) and leaves biomass, DBH and crown biomass (sum up of  leaves,  twigs and branches) as well as betwee

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14

Sidabras, Nerijus, and Algirdas Augustaitis. "Application Perspectives of the Leaf Area Index (LAI) Estimated by the Hemiview System in Forestry." Proceedings of the Latvia University of Agriculture 33, no. 1 (2015): 26–34. http://dx.doi.org/10.1515/plua-2015-0004.

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AbstractLeaf area index (LAI) is widely used to describe the main characteristics of forest stands such as cover intensity at different forest levels from moss to tree as well as main stand dendrometric parameters. Hemispherical canopy photograph was used for analyzing quality and quantity of coniferous forest in Aukstaitija national park. Different sampling systems from single plots to aggregating them into stands allowed assessing significance of LAI detected by the HemiView system in forestry without special preparation. The obtained data revealed that the use of hemispheric photograph for

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15

Clark, Joshua, and Glen Murphy. "Estimating forest biomass components with hemispherical photography for Douglas-fir stands in northwest Oregon." Canadian Journal of Forest Research 41, no. 5 (2011): 1060–74. http://dx.doi.org/10.1139/x11-013.

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Accurately and quickly identifying inventories of forest biomass has become increasingly important for a variety of reasons. Current allometric equations require time-consuming tree-level measurements, but ground-based remote sensing could lead to faster estimates of forest biomass. Hemispherical photography (HP) is one potential technology that could estimate forest biomass quickly and efficiently. This analysis is based on a study in northwest Oregon where 15 Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plots were destructively sampled, and 60 HPs (four per plot) were taken. One photo

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16

Basuki, Tyas Mutiara. "Leaf Area Index Derived from Hemispherical Photograph and its Correlation with Aboveground Forest Biomass." Indonesian Journal of Forestry Research 2, no. 1 (2015): 31–41. http://dx.doi.org/10.20886/ijfr.2015.2.1.31-41.

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17

Basuki, Tyas Mutiara. "LEAF AREA INDEX DERIVED FROM HEMISPHERICAL PHOTOGRAPH AND ITS CORRELATION WITH ABOVEGROUND FOREST BIOMASS." Indonesian Journal of Forestry Research 2, no. 1 (2015): 31–41. https://doi.org/10.59465/ijfr.2015.2.1.31-41.

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Анотація:

Leaf area index (LAI) is one of the key physical factors in the energy exchange between terrestrial ecosystem and atmosphere. It determines the photosynthesis process to produce biomass and plays an important role in performing forest stand reflectance. Therefore building relationship between LAI and biomass from field measurements can be used to develop allometric equations for biomass estimation. This paper studies the relationship between diameter at breast height (DBH) and leaves biomass, DBH and crown biomass (sum up of leaves, twigs and branches) as well as between LAI and leaves biomass

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18

Mutiara Basuki, Tyas. "LEAF AREA INDEX DERIVED FROM HEMISPHERICAL PHOTOGRAPH AND ITS CORRELATION WITH ABOVE-GROUND FOREST BIOMASS." Indonesian Journal of Forestry Research 2, no. 1 (2015): 31–41. http://dx.doi.org/10.20886/ijfr.2015.2.1.647.31-41.

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19

Richardson, Jeffrey J., Christian E. Torgersen, and L. Monika Moskal. "Lidar-based approaches for estimating solar insolation in heavily forested streams." Hydrology and Earth System Sciences 23, no. 7 (2019): 2813–22. http://dx.doi.org/10.5194/hess-23-2813-2019.

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Abstract. Methods to quantify solar insolation in riparian landscapes are needed due to the importance of stream temperature to aquatic biota. We have tested three lidar predictors using two approaches developed for other applications of estimating solar insolation from airborne lidar using field data collected in a heavily forested narrow stream in western Oregon, USA. We show that a raster methodology based on the light penetration index (LPI) and a synthetic hemispherical photograph approach both accurately predict solar insolation, explaining more than 73 % of the variability observed in p

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20

Bellingham, P. J., E. V. J. Tanner, P. M. Rich, and T. C. R. Goodland. "Changes in light below the canopy of a Jamaican montane rainforest after a hurricane." Journal of Tropical Ecology 12, no. 5 (1996): 699–722. http://dx.doi.org/10.1017/s0266467400009883.

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ABSTRACTHurricane Gilbert caused disturbance to Jamaican montane rainforests in 1988. This study provides a detailed characterization of landscape-level changes in light below the canopy of these forests after the hurricane. Hemispherical photographs were taken below the forest canopy at four sites at permanent points 1 m above the ground between 7 and 33 mo after the hurricane. For each photograph photosynthetically active radiation (PAR) was computed. PAR declined exponentially in all sites during the period of measurement. During the first 24 mo after the hurricane, PAR beneath the canopy w

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21

Inoue, A., K. Yamamoto, and N. Mizoue. "Comparison of automatic and interactive thresholding of hemispherical photography." Journal of Forest Science 57, No. 2 (2011): 78–87. http://dx.doi.org/10.17221/68/2010-jfs.

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This study presents the effects of operator bias and variation in interactive thresholding on the estimation of light environment using hemispherical photography. Twenty-one hemispherical photographs taken beneath a wide range of canopy densities were visually converted to binary images twice by 21 operators, and then the gap fraction was computed from the images. The interactive threshold varied greatly among the different operators and within a single operator, which resulted in a considerable operator bias and variation in the gap fraction. This study also compared three widely used automat

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22

Jakoplić, A., S. Vlahinić, B. Dobraš, and D. Franković. "Sky Image Analysis and Solar Power Forecasting: A Convolutional Neural Network Approach." Renewable Energy and Power Quality Journal 21, no. 1 (2023): 456–61. http://dx.doi.org/10.24084/repqj21.355.

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Recently, the share of renewable sources in the energy mix of production units has been steadily increasing. The unpredictability of renewable sources leads to difficulties in planning, managing and controlling the electric energy system (EES). One of the ways to reduce the negative impact of unpredictable renewable sources is to predict the availability of these energy sources. Short-term forecasting of photovoltaic power plant production is one of the tools that enable greater integration of renewable energy sources into the EES. One way to gather information for the short-term forecast prod

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23

Wibowo, R. Y. K. S., R. Hermawan, and S. B. Rushayati. "Stemflow and throughfall on several tree architectural models." IOP Conference Series: Earth and Environmental Science 918, no. 1 (2021): 012002. http://dx.doi.org/10.1088/1755-1315/918/1/012002.

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Abstract The aim of developing urban forests for steep areas is to prevent erosion. Erosion can be caused by stemflow and throughfall. The difference in stemflow and throughfall is thought to be due to differences in the tree architecture model. The study investigates the effects of several tree architectural models on the amount of stemflow and throughfall. It is hoped that data and information of this research can be taken into consideration in selecting tree species for the benefit of soil and water conservation in urban forest areas that have the potential for erosion and sedimentation. Th

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24

Ishida, Megumi. "Automatic thresholding for digital hemispherical photography." Canadian Journal of Forest Research 34, no. 11 (2004): 2208–16. http://dx.doi.org/10.1139/x04-103.

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This paper proposes an automatic thresholding method for the discrimination of sky and canopy elements in color hemispherical photographs taken with a digital camera (Nikon Coolpix 950). The exposures for photography were principally determined on the basis of zenith luminance. DIFphoto, which is diffuse transmittance calculated from the hemispherical photographs, was related to DIFsensor, which is diffuse transmittance measured directly with a photosynthetic photon flux density sensor. First, the thresholds for calculation of DIFphoto were manually assessed in the photographs to obtain the be

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25

Díaz, Gastón Mauro, and José Daniel Lencinas. "Model-based local thresholding for canopy hemispherical photography." Canadian Journal of Forest Research 48, no. 10 (2018): 1204–16. http://dx.doi.org/10.1139/cjfr-2018-0006.

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Canopy hemispherical photography (HP) is widely used to estimate forest structural variables. To achieve good results with HP, a classification algorithm is needed to produce binary images to accurately estimate the gap fraction. Our aim was to develop a local thresholding method for binarizing carefully acquired hemispherical photographs. The method was implemented in the R package “caiman”. Working with photographs of artificial structures and using a linear model, our method turns the cumbersome problem of finding the optimal threshold value into a simpler one, which is estimating the digit

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26

Zhao, Qingxia, Fei Wang, Jun Zhao, Jingjing Zhou, Shichuan Yu, and Zhong Zhao. "Estimating Forest Canopy Cover in Black Locust (Robinia pseudoacacia L.) Plantations on the Loess Plateau Using Random Forest." Forests 9, no. 10 (2018): 623. http://dx.doi.org/10.3390/f9100623.

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The forest canopy is the medium for energy and mass exchange between forest ecosystems and the atmosphere. Remote sensing techniques are more efficient and appropriate for estimating forest canopy cover (CC) than traditional methods, especially at large scales. In this study, we evaluated the CC of black locust plantations on the Loess Plateau using random forest (RF) regression models. The models were established using the relationships between digital hemispherical photograph (DHP) field data and variables that were calculated from satellite images. Three types of variables were calculated f

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27

Fan, Weiliang, Jun Wu, Guang Zheng, et al. "Retrieving the Leaf Area Index of Dense and Highly Clumped Moso Bamboo Canopies from Sentinel-2 MSI Data." Remote Sensing 17, no. 11 (2025): 1891. https://doi.org/10.3390/rs17111891.

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The effects of leaf clumping on leaf area index (LAI, m2·m−2) retrieval have been proved by several studies. For dense and highly clumped Moso bamboo canopies, LAI is usually retrieved using the SAIL-series models that do not account for leaf clumping, although these retrievals are subsequently successfully validated by indirect ground-based methods that do account for leaf clumping. In order to explore these two seemingly contradictory results, LAIs of 21 Moso bamboo canopies retrieved by the GOST2 model (incorporating leaf clumping), the 4SAIL model and the SNAP tool (both without leaf clump

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28

Gonsamo, Alemu, Jean-Michel N. Walter, and Petri Pellikka. "Sampling gap fraction and size for estimating leaf area and clumping indices from hemispherical photographs." Canadian Journal of Forest Research 40, no. 8 (2010): 1588–603. http://dx.doi.org/10.1139/x10-085.

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Hemispherical photography is becoming a popular technique for gap fraction measurements to characterize biophysical parameters and solar radiation in plant canopies. One of the crucial steps in the measurement of canopy gap fraction using hemispherical photography is determining the resolution of the sampling grid. In this work, the effects of varying resolutions of sampling grids by modifying the angle widths of zenithal annuli and azimuthal sectors were evaluated for leaf area and clumping indices computations. Sensitivity analysis was performed to test these effects using artificial photogr

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29

Brandão, Ziany N., and João H. Zonta. "Hemispherical photography to estimate biophysical variables of cotton." Revista Brasileira de Engenharia Agrícola e Ambiental 20, no. 9 (2016): 789–94. http://dx.doi.org/10.1590/1807-1929/agriambi.v20n9p789-794.

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ABSTRACT The Leaf Area Index (LAI) is a key parameter to evaluate the vegetation spectral response, estimating plant nutrition and water requirements. However, in large fields is difficult to obtain accurate data to LAI determination. Therefore, the objective of this study was the estimation of LAI, biomass and yield of irrigated cotton through digital hemispherical photography. The treatments consisted of four nitrogen doses (0, 90, 180 and 270 kg ha-1) and four phosphorus doses (0, 120, 240 and 360 kg ha-1). Digital hemispherical photographs were collected under similar sky brightness condit

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30

Sima, Lei, Yisha Liu, Xiaowei Shang, Qi Yuan, and Yunming Zhang. "A Review of the Application of Hemispherical Photography in Urban Outdoor Thermal Comfort Studies." Buildings 15, no. 1 (2025): 123. https://doi.org/10.3390/buildings15010123.

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Thermal comfort studies are paramount in enhancing future urban living conditions, and hemispherical photography has emerged as a widely employed field measurement technique in outdoor thermal comfort research. This comprehensive review systematically analyzed 142 outdoor thermal comfort studies conducted over the past decade using hemispherical photography methods, revealing that its primary application lies in objectively describing environmental information and constructing associated indices. In contrast, the number of studies focusing on subjectively assessing environmental factors remain

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31

Rich, Paul M. "Characterizing plant canopies with hemispherical photographs." Remote Sensing Reviews 5, no. 1 (1990): 13–29. http://dx.doi.org/10.1080/02757259009532119.

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32

Wang, G. G., J. Su, and J. R. Wang. "Height growth of planted black spruce seedlings in response to interspecific vegetation competition: a comparison of four competition measures at two measuring positions." Canadian Journal of Forest Research 30, no. 4 (2000): 573–79. http://dx.doi.org/10.1139/x99-238.

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Four simple measures of interspecific competition (percent cover visually estimated in the field, percent cover derived from hemispherical photographs, percent full sunlight measured by a ceptometer, and gap light index derived from hemispherical photographs) obtained at two reference positions (the top and the middle of crop seedlings) were evaluated in relation to two growth variables (relative height growth rates in 1998 and during 1996 to 1998) of black spruce (Picea mariana (Mill.) BSP) seedlings planted on boreal mixedwood sites in southeastern Manitoba. The four competition measures ass

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33

Englund, Sylvia R., Joseph J. O'Brien, and David B. Clark. "Evaluation of digital and film hemispherical photography and spherical densiometry for measuring forest light environments." Canadian Journal of Forest Research 30, no. 12 (2000): 1999–2005. http://dx.doi.org/10.1139/x00-116.

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This study presents the results of a comparison of digital and film hemispherical photography as means of characterizing forest light environments and canopy openness. We also compared hemispherical photography to spherical densiometry. Our results showed that differences in digital image quality due to the loss of resolution that occurred when images were processed for computer analysis did not affect estimates of unweighted openness. Weighted openness and total site factor estimates were significantly higher in digital images compared with film photos. The differences between the two techniq

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34

Sabol, Jan, Zdeněk Patočka, and Tomáš Mikita. "Usage of Lidar Data for Leaf Area Index Estimation." GeoScience Engineering 60, no. 3 (2014): 10–18. http://dx.doi.org/10.2478/gse-2014-0013.

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Abstract Leaf area index (LAI) can be measured either directly, using destructive methods, or indirectly using optical methods that are based on the tight relationship between LAI and canopy light transmittance. Third, innovative approach for LAI measuring is usage of remote sensing data, especially airborne laser scanning (ALS) data shows itself as a advisable source for purposes of LAI modelling in large areas. Until now there has been very little research to compare LAI estimated by the two different approaches. Indirect measurements of LAI using hemispherical photography are based on the t

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35

Diaz, Gaston M., and Jose D. Lencinas. "Enhanced Gap Fraction Extraction From Hemispherical Photography." IEEE Geoscience and Remote Sensing Letters 12, no. 8 (2015): 1785–89. http://dx.doi.org/10.1109/lgrs.2015.2425931.

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36

Hederová, Lucia, Martin Macek, Jan Wild, et al. "Ecologically relevant canopy openness from hemispherical photographs." Agricultural and Forest Meteorology 330 (March 2023): 109308. http://dx.doi.org/10.1016/j.agrformet.2023.109308.

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Mitrović, Suzana, Milorad Veselinović, Nevena Čule, et al. "Determination of leaf area index (LAI) at Level II Sample plots according ICP manual." Sustainable Forestry: Collection, no. 83-84 (2021): 65–77. http://dx.doi.org/10.5937/sustfor2183065m.

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The paper describes the methodology for determining LAI according to the ICP forest methodology, where hemispherical photographs were taken on a network of fixed points placed on the surfaces of three Sample plots Level II. Hemispherical photographs were processed by the Hemisfer software package. The data obtained by image processing were entered into the ICP Forests database. The obtained LAI values represent the response to the state of vegetation under the influence of different ecological conditions as well as anthropogenic influences, and will be the part of future annual monitoring at S

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38

Beckschäfer, P., D. Seidel, C. Kleinn, and J. Xu. "On the exposure of hemispherical photographs in forests." iForest - Biogeosciences and Forestry 6, no. 4 (2013): 228–37. http://dx.doi.org/10.3832/ifor0957-006.

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39

Inoue, Akio, Kazukiyo Yamamoto, Nobuya Mizoue, and Yuichiro Kawahara. "Estimation of Relative Iilluminance using Digital Hemispherical Photography." Journal of Forest Planning 8, no. 2 (2002): 67–70. http://dx.doi.org/10.20659/jfp.8.2_67.

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40

Facchi, Arianna, Gabriele Baroni, Mirco Boschetti, and Claudio Gandolfi. "COMPARING OPTICALAND DIRECT METHODS FOR LEAFAREA INDEX DETERMINATION IN A MAIZE CROP." Journal of Agricultural Engineering 41, no. 1 (2010): 33. http://dx.doi.org/10.4081/jae.2010.1.33.

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Leaf area index (LAI) is a crucial variable in the modelling of many hydrological processes. Destructive sampling of LAI is extremely time-consuming, thus not suitable for monitoring temporal/spatial variations of the variable. In the last fifty years optical instruments retrieving LAI from more easily measurable variables (i.e. transmitted radiation through canopies) have been developed. Several instruments are available on the market, but very few are the studies comparing LAI estimates in agricultural crops. In this paper three optical instruments are compared with destructive sampling for

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41

Song, Guo-Zhang Michael, David Doley, David Yates, Kuo-Jung Chao, and Chang-Fu Hsieh. "Improving accuracy of canopy hemispherical photography by a constant threshold value derived from an unobscured overcast sky." Canadian Journal of Forest Research 44, no. 1 (2014): 17–27. http://dx.doi.org/10.1139/cjfr-2013-0082.

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High image discrimination threshold values tend to be given to canopy hemispherical photographs (CHPs) with high exposure (resulting in bright images), but the effects of exposure on image threshold have been overlooked. A model canopy system was developed to precisely manipulate exposure (in relation to reference exposure measured from an unobscured overcast model sky), canopy openness, gap fragmentation and sky illumination of CHPs. We showed that there was a numerical trade-off relationship between exposure and image threshold of CHPs, whereas the last three factors had negligible effects o

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42

Nascimento, André Rosalvo Terra, Jeanine Maria Felfili Fagg, and Christopher William Fagg. "Canopy openness and lai estimates in two seasonally deciduous forests on limestone outcrops in central Brazil using hemispherical photographs." Revista Árvore 31, no. 1 (2007): 167–76. http://dx.doi.org/10.1590/s0100-67622007000100019.

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Patches of seasonally dry tropical forests occur on limestone outcrops in Central Brazil surrounded by the dominant savanna vegetation. They contain valuable timber species but are threatened by farming and mining activities. The objective of this study was to describe canopy opening and light relations in two seasonally deciduous dry forests on slopes and limestone outcrops, in the Paranã valley at the northeastern region of the Goiás state, Brazil. The studied forests were in the Fazenda Sabonete in Iaciara-Go and Fazenda Forquilha in Guarani-GO. Woody plants were sampled in 25 (20 x 20 m) p

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Rhoads, Anne G., Steven P. Hamburg, Timothy J. Fahey, Thomas G. Siccama, and Richard Kobe. "Comparing direct and indirect methods of assessing canopy structure in a northern hardwood forest." Canadian Journal of Forest Research 34, no. 3 (2004): 584–91. http://dx.doi.org/10.1139/x03-231.

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Several methods exist for measuring forest canopies following disturbance, and the biases and differences among them are unclear. We compared techniques for measuring the northern hardwood forest's canopy structure at the Hubbard Brook Experimental Forest, New Hampshire, following the severe ice storm of January 510, 1998. Methods included leaf area index (LAI) using LI-COR's LAI-2000, visual damage assessments based on tree branch loss, radiation estimates from hemispherical photographs, and LAI determined from litterfall. LAI-2000 measurements were not significantly related to visual damage

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Kobe, Richard K., and Leah J. Hogarth. "Evaluation of irradiance metrics with respect to predicting sapling growth." Canadian Journal of Forest Research 37, no. 7 (2007): 1203–13. http://dx.doi.org/10.1139/x06-320.

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Accurate and efficient measurement of photosynthetically active radiation (PAR) is critical in ecological studies. We evaluated 25 metrics of PAR with respect to predicting growth of sugar maple ( Acer saccharum Marsh.) and white ash ( Fraxinus americana L.) saplings from understory to large gap conditions. PAR metrics were derived from gallium arsenide photodiodes, hemispherical canopy photographs (film and digital), and a LI-COR LAI-2000 plant canopy analyzer. In general, percent canopy openness, estimated with film photographs or LAI-2000, best predicted growth. Mean daily photosynthetic ph

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45

Li, Kexin, Xinwang Huang, Jingzhe Zhang, et al. "A New Method for Forest Canopy Hemispherical Photography Segmentation Based on Deep Learning." Forests 11, no. 12 (2020): 1366. http://dx.doi.org/10.3390/f11121366.

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Research Highlights: This paper proposes a new method for hemispherical forest canopy image segmentation. The method is based on a deep learning methodology and provides a robust and fully automatic technique for the segmentation of forest canopy hemispherical photography (CHP) and gap fraction (GF) calculation. Background and Objectives: CHP is widely used to estimate structural forest variables. The GF is the most important parameter for calculating the leaf area index (LAI), and its calculation requires the binary segmentation result of the CHP. Materials and Methods: Our method consists of

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INOUE, Akio, Atsunori OKAMURA, Nobuya MIZOUE, Yukio TERAOKA, and Morio IMADA. "Estimation of Relative Illuminance in Forests using Hemispherical Photographs." Journal of Forest Planning 2, no. 2 (1996): 125–29. http://dx.doi.org/10.20659/jfp.2.2_125.

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47

Gonsamo, Alemu, and Petri Pellikka. "The computation of foliage clumping index using hemispherical photography." Agricultural and Forest Meteorology 149, no. 10 (2009): 1781–87. http://dx.doi.org/10.1016/j.agrformet.2009.06.001.

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48

Lang, Mait, and Jan Pisek. "Tracking the long-term structure changes of a mature deciduous broadleaf forest stand using digital hemispherical photography." Forestry Studies 70, no. 1 (2019): 80–87. http://dx.doi.org/10.2478/fsmu-2019-0007.

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Abstract Hemispherical photography provides permanent records of forest canopy structure. We analysed digital hemispherical images taken during the period of 2007–2018 in a mature silver birch stand located in Järvselja, Estonia. The stand was thinned in 2004. Understory trees were removed in the spring of 2018. Images were processed using the LinearRatioSC method. Effective plant area index Leff during the leafless phenophase increased as a result of tree growth from 0.92 to 1.24 and understory cutting was not detectable. During the full foliage condition Leff increased from 3.6 in 2008 to 5.

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이덕재. "Canopy Closure in Visiting Forest Trails Using a Hemispherical Photography." Journal of Korean institute of Forest Recreation 20, no. 1 (2016): 35–42. http://dx.doi.org/10.34272/forest.2016.20.1.004.

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Toda, Kentaro, and Akihiro Nakamura. "A Development of Solar Radiation Estimate Program Using Hemispherical Photographs." Journal of the Japanese Society of Revegetation Technology 27, no. 1 (2001): 154–59. http://dx.doi.org/10.7211/jjsrt.27.154.

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