항공 라이다데이터를 이용한 개별수목탐지 및 평균수고추정

황세란,이미진,이임평 대한공간정보학회 2012 Spatial Information Research Vol.20 No.3

As the necessity of forest conservation and management has been increased, various forest studies using LIDAR data have been actively performed. These studies often utilize the tree height as an important parameter to measure the forest quantitatively. This study thus attempt to apply two representative methods to estimate tree height from airborne LIDAR data and compare the results. The first method based on the detection of the individual trees using a local maximum filter estimates the number of trees, the position and heights of the individual trees, and the mean tree height. The other method estimates the maximum and mean tree height, and the crown mean height for each grid cell or the entire area from the canopy height model (CHM) and height histogram. In comparison with the field measurements, 76.6% of the individual trees are detected correctly; and the estimated heights of all trees and only conifer trees show the RMSE of 1.91m and 0.75m, respectively. The tree mean heights estimated from CHM retain about 1~2m RMSE, and the histogram method underestimates the tree mean height with about 0.6m. For more accurate derivation of diverse forest information, we should select and integrate the complimentary methods appropriate to the tree types and estimation parameters. 산림의 보존과 관리에 대한 필요성이 점차 증가하면서 항공 라이다데이터를 이용한 산림연구가 활발히 수행되고 있다. 이러한 산림연구에서 수목고도는 정량적인 산림측정을 위한 중요한 변수로 이용된다. 이에 본 연구는 항공 라이다데이터로부터 수목고도 추정을 위한 대표적인 두 종류의 방법을 적용하고 그 결과를 비교분석한다. Local maximum 필터링에 기반한 개별수목탐지 방법으로 개별수목의 수, 위치, 높이 및 평균수고를, 수목고도모델 또는 히스토그램을 이용한 평균수고 추정방법으로 개별격자 또는 전체영역에 대한 최대, 평균수고, 평균 수관고를 추정한다. 현장에서 실측한 검증데이터와 비교한 결과 개별 수목은 76.6%의 정확도로 탐지되었으며 개별수고는 전체 수종의 경우 1.91m, 침엽수종에 대해서는 0.75m의 RMSE로 추정되었다. 반면 수목고도모델을 이용하여 추정된 평균수고는 약 1~2m의 RMSE를 보였으며, 히스토그램을 이용하여 추정된 평균수고는 약 0.6m 과소 추정되었다. 정확하고 다양한 산림정보 추출을 위해 수종 및 추정인자에 따라 적합한 상호보완적인 방법을 선택하고 융합하는 것이 필요하다.

Estimation of apple tree canopy height and area coverage using 3D LiDAR point clouds

( Rejaul Karim ),( Mohammod Ali ),( Shahriar Ahmed ),( Ashrafuzzaman Gulandaz ),( Nasim Reza ),( Justin Sung ),( Sun-ok Chung ) 한국농업기계학회 2023 한국농업기계학회 학술발표논문집 Vol.28 No.1

Phenotyping characteristics (Tree height and canopy area) are crucial factors for growth and yield monitoring. This study aimed to use 3D LiDAR point clouds to estimate the apple tree canopy height and area using different digital models. The traditional method of manually measuring trees at various heights and canopies is time-consuming and labor-intensive, so the study aimed to automate the process using 3D LiDAR (VLP-16) to collect point clouds of orchard apple trees. The data was pre-processed using a 3D point cloud data processing software, and automatic segmentation methods were applied to calculate the canopy height and area for selected orchard tree samples. The processed 3D point cloud data was converted into raster images for visualization and estimation of orchard tree canopy height and area coverage using digital surface model (DSM), digital elevation model (DEM), and canopy height model (CHM). Python program was also used for visualization and reconstruction of trees from the preprocessed data. The accuracy of the sensor-based measuring method was compared to manually-acquired ground truth data, but the accuracy was worse by 15%. The study found that the proposed system could efficiently segment and measure tree canopy height and area coverage. The proposed models showed comparatively lower result than manual measurement, with an sensor based average tree canopy height and area of 2.1 m and 5.83 m², respectively, where as measured values were 2.4±0.2 m and 6.0±0.21 m², respectively. However, the findings of this study can still contribute to further horticultural crops research particularly for orchard fruits production and yield monitoring.

Assessment of the effects of thinnings in scots pine plantations in Mongolia: a comparative analysis of tree growth and crown development based on dominant trees

Batsaikhan Ganbaatar,Tsogtbaatar Jamsran,Alexander Gradel,Gerelbaatar Sukhbaatar 한국산림과학회 2021 Forest Science And Technology Vol.17 No.3

The post-thinning stand density and spacing in forest plantations influence individual tree growth and crown development, and the changes detected in dominant tree growth are a good indication of the thinning effect. The objective of this study was to determine the effects of different thinning intensities on diameter and height growth in a Scots pine (Pinus sylvestris L.) plantation. The field measurements were carried out between 2016 and 2020 on a Scots pine plantation, growing in Selenge province of northern Mongolia. Following this, experimental thinnings were carried out with different intensities. Thinning treatments comprised thinning with very low, low, medium, and high intensities, as well as an unthinned control stand. Stem analyses were performed to calculate the annual and cumulative diameter, height, and volume growth. For tree crown measurements several parameters were analyzed: crown diameter, crown projection area, and crown index. A total of 300 trees (5 treatments3 replications20 dominant trees from each plot) were subjected to the comparative analyses. This study revealed that thinning showed a stronger positive effect on diameter and volume growth of dominant trees in the plantation. Our results showed a gradual increase in diameter, basal area, and volume growth depending on the thinning intensity. An ANOVA test for growth analyses of dominant trees showed a significant difference in diameter (p<0.0001) and height (p<0.0001) growth performance following experimental felling with different thinning intensities. Finally we elaborated linear mixed effect models (LMM) for tree growth between 2016 and 2020 of selected dominant trees. With the help of the LMM we analyzed and described the thinning impact on DBH, BA, height, volume and crown diameter. The models confirmed that higher thinning intensity triggered growth of the response variables except for height. A greater height growth was found in very low (10%) and low (15%) intensity treatments. Due to reduction of competition and optimization of the distance between individuals, thinnings contributed to a relatively faster development of the tree crown in radial directions. Based on our analysis results and comparative graphs representing post-thinning dominant tree growth in diameter, height, basal area, and volume, we recommend medium- (30%) and high-intensity (45%) thinnings as at the beginning stage of plantation establishment.

새만금 간척지 곰솔과 졸참나무 수림대의 초기 수고 생장 모형 추정

이창헌,김현,이총규,강학모,최수임 한국도서(섬)학회 2019 韓國島嶼硏究 Vol.31 No.3

This study aimed to provide information on the growth status of tree belts for the establishment and management of forest zone in the development of the Saemangeum reclaimed land. The target location of this study was the tree belts established at the Saemangeum reclaimed land, and planted with Pinus thunbergii and Quercus serrata in November 2012. The height growth model was estimated using height growth data collected over four years from November 2012 to October 2016, and rearranged to include all possible growth measurements determined on a yearly basis. Moreover, the optimal height growth model was estimated by fitting the rearranged data to the non-linear anamorphic and polymorphic algebraic difference equations showing a lying S-shape that is similar to the growth pattern of trees. In case of both P. thunbergii and Q. serrata tree belts, the anamorphic algebraic difference equation exhibited a biased residuals pattern (Gompertz and Schumacher) or was likely to cause certain problem in estimating a model (Chapman-Richards and Hossfeld). All polymorphic equations, other than the Hossfeld equation, demonstrated excellent fit to the rearranged data. The results of development in the growth model revealed that the Chapman-Richards polymorphic equation was most suitable for the initial height growth model of the P. thunbergii tree belt, while the Gompertz polymorphic equation was most suitable for the Q. serrata tree belt. In case of both tree belts, the height estimation showed very high accuracy (P. thunbergii tree belt, -0.06 cm in average residuals and 41.5 cm in standard deviation; Q. serrata tree belt, 0.5 cm in average residuals and 46.2 cm in standard deviation). This study is significant and has value over other studies, as it targeted the artificial tree belts established at the Saemangeum reclaimed land. In addition, the estimated model can provide robust scientific data required for management and administration of the tree belts of P. thunbergii and Q. serrata during the initial establishment stage. 본 연구는 새만금 간척지 개발에 따른 수림대의 조성 및 관리에 필요한 수목의 생장 정보를 제공하고자 수행하였다. 연구 대상지는 새만금 노출 간척지에 곰솔과 졸참나무로 조성된 수림대로써, 2012년도 11월에 식재하였으며, 2016년도 10월까지 조사한 4년간의 수고 생장 데이터를 이용하여 수고 생장 모형을 추정하였다. 수고 생장 모형 추정을 위한 데이터는 1년 단위의 모든 가능한 생장 측정 기간을 포함하는 데이터로 재배열하여 이용하였다. 또한, 수고 생장 모형의 추정은 수목의 생장 패턴과 유사한 누운 S자 형태를 나타내는 동형과 다형의 비선형 대수차분 방정식에 재배열된 데이터를 적합하여 최적의 수고 생장 모형을 추정하였다. 곰솔 수림대의 경우, 동형 방정식은 잔차의 패턴이 편의를 보였거나(Gompertz, Schumacher) 모형을 추정함에 있어서 문제점이 발생할 수 있는 것으로 분석되었다(Chapman-Richards, Hossfeld). 다형 방정식 중 Hossfeld 방정식을 제외한 나머지 방정식들은 재배열된 데이터와 우수한 적합성을 보였으며, 이를 이용하여 생장 모형을 전개한 결과 Chapman-Richards 다형 방정식이 곰솔 수림대의 초기 수고 생장 모형으로 가장 적절하였다. 이때 잔차의 평균은 -0.06㎝, 표준편차는 41.5㎝로 수고 추정에 있어서 고도의 정확도를 가지고 있는 것으로 분석되었다. 졸참나무 수림대의 경우, 동형 방정식은 잔차 패턴의 편의(Gompertz, Schumacher), 모형 추정에 있어서의 문제점 발생 가능성(Chapman-Richards, Hossfeld)이 확인되었다. 다형 방정식 중 Hossfeld 방정식을 제외한 나머지 방정식들에서 재배열된 데이터와 우수한 적합성을 보였으며, 이를 이용하여 생장 모형을 전개한 결과 Gompertz 다형 방정식이 졸참나무 수림대의 초기 수고 생장 모형으로 가장 적절하였다. 이때 잔차의 평균은 0.5㎝, 표준편차는 46.2㎝로 고도의 정확도를 나타내는 모형인 것으로 분석되었다. 본 연구는 새만금 노출 간척지에 인공 조성된 수림대를 대상으로 하였다는 점에 있어서 기존 연구들과는 다른 중요성과 가치가 있으며, 추정된 모형은 곰솔과 졸참나무 수림대의 조성 초기의 합리적이고 과학적인 경영·관리에 필요한 자료로 활용될 수 있을 것이다.

흉고직경과 수고에 의한 소나무(Pinus densiflora S. et Z.)의 지상부와 지하부 생체량 추정

이도형 ( Do Hyung Lee ) 한국산림과학회 2004 한국산림과학회지 Vol.93 No.3

This study was conducted to elucidate the relationship between the root structure and the crown structure of Pinus densiflora S. et Z., and thereafter to obtain the regression equation for the estimation of relative root and needle biomass using the tree height and diameter of breast height(DBH) without measurement of root and needle biomass. The study sites was Gyeongsan, Ulzin and Kyeongju stands located in south eastern part of Korea. Five dominant or co-dominant trees of 25 to 45 year-old were selected in each site and tree height, diameter of breast height, tree age, weight of total needle and branch, cross section and sapwood area at breast height were measured for biomass of above ground part. And also for biomass of below ground part, the length of root, the number of root, the weight of root, the cross section area of root etc. by dividing the horizontal and vertical roots were measured. The significantly correlation was shown between the biomass of most of variables of above ground parts and those of below ground parts, and the biomass of above- and ground parts was not significantly correlated with the age of tree. The regression equation for the diameter of breast height to the total weight of root was Y=-9.39+2.80X and decision coefficient was 0.67 and also to the total weight of needle, regression equation was Y=-16.52+ 1.79X and decision coefficient was 0.86. The regression equation of the tree height to the weight of horizontal root was Y=-5.54+1.00X(r²=0.71) and to the total weight of needle, regression equation was Y=-23.00+3.41X(r²=0.83). The weight of total branches and needles, and the sapwood area at breast height of above ground parts showed highly positive relationship with below ground biomass. The results obtained from this study can be used to the estimating of biomass of below ground using variables of above ground such as DBH and tree height of the 25 to 45 year-old Pinus densiflora stands.

항공 LiDAR 기반 Local Maxima를 이용한 산림지역 수목정보 추출 자동화

최인하 ( In-ha Choi ),남상관 ( Sang-kwan Nam ),김승엽 ( Seung-yub Kim ),이동국 ( Dong-gook Lee ) 대한원격탐사학회 2023 大韓遠隔探査學會誌 Vol.39 No.5

현재 국가산림자원조사(National Forest Inventory, NFI)는 인력에 의한 수목정보를 수집하고 있어 조사 범위와 시간의 한계가 따른다. 항공 Light Detection And Ranging (LiDAR) 및 항공 사진 등을 이용하여 넓은 지역의 수목 정보를 추출하기 위한 연구가 활발하게 진행되고 있으나 수목의 간격이 넓은 지역이거나 수목의 간격이 일정하게 배치된 지역을 대상으로 이루어지고 있어 우리나라 산림지역 특성을 반영하지 못하고 있다. 이에 본 연구에서는 항공 LiDAR를 이용하여 수치표면모델(Digital Surface Model, DSM), 수치표고모델(Digital Elevation Model, DEM), 수목높이모델(Canopy Height Model, CHM) 영상을 생성한 후 local maxima 기법을 통해 수고를 추출하고 산정식을 통해 흉고직경(Diameter at Breast Height, DBH)을 산정하는 방법론을 제안하였다. 제안한 방법론을 통해 추출한 수목의 검출 정확도는 매목지구별 각 88.46%, 86.14%, 84.31%로 나타났으며, 수고 값을 기반으로 산정한 DBH의 평균제곱근오차(Root Mean Squared Error, RMSE)가 5 cm 내외로 나타나 제안한 방법론의 활용 가능성을 확인하였다. 향후 다양한 유형의 산림에 대한 표준화 연구를 진행한다면 수작업으로 이루어지는 국가산림자원조사의 자동화 적용 범위를 확대할 수 있을 것으로 사료된다. Currently, the National Forest Inventory (NFI) collects tree information by human, so the range and time of the survey are limited. Research is actively being conducted to extract tree information from a large area using aerial Light Detection And Ranging (LiDAR) and aerial photographs, but it does not reflect the characteristics of forest areas in Korea because it is conducted in areas with wide tree spacing or evenly spaced trees. Therefore, this study proposed a methodology for generating Digital Surface Model (DSM), Digital Elevation Model (DEM), and Canopy Height Model (CHM) images using aerial LiDAR, extracting the tree height through the local Maxima, and calculating the Diameter at Breath Height (DBH) through the DBH-tree height formula. The detection accuracy of trees extracted through the proposed methodology was 88.46%, 86.14%, and 84.31%, respectively, and the Root Mean Squared Error (RMSE) of DBH calculated based on the tree height formula was around 5cm, confirming the possibility of using the proposed methodology. It is believed that if standardized research on various types of forests is conducted in the future, the scope of automation application of the manual national forest resource survey can be expanded.

강전정에 의한 저수고 감나무의 시비량 조절에 따른 수체 생장 및 과실 생장 반응

최성태(Seong-Tae Choi),박두상(Doo-Sang Park),안광환(Gwang-Hwan Ahn),김성철(Sung-Chul Kim),최태민(Tae-Min Choi),노치웅(Chi?Woong Rho) 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.2

Lowering tree height has been a key practice for efficient management of persimmon orchards. This experiment was conducted to assess whether fertilization rates could be reduced after lowering the tree height by heavy pruning. Twelve-year-old ‘Uenishiwase’ persimmon trees were lowered to 2 m from over 3 m by -severe dormant pruning, and then conventional fertilization rate was applied to some trees in April (N 224 g, P₂O5 172 g, and K₂O 172 g per tree), June (N 112 g and K₂O 99 g per tree), and October (N 112 g and K₂O 99 g per tree). At the same time, 1/3 or 2/3 of the conventional rate and none were applied to other trees, respectively. Non-application decreased shoot length and reduced number of unnecessary secondary shoots by 39% compared with the conventional rate, not affecting yield and weight, color, firmness, and soluble solids of fruits. No significant difference was also found in the yield and the fruit characteristics among the trees fertilized with different rates. Concentrations of soluble sugars, starch, N, and K of dormant shoots in March of the following year were not significantly changed by the different treatments of the previous year. There was no significant difference of shoot growth and yield among the treatments the following year when the same fertilization rate was supplied to all the trees. Results indicated that fertilization rate could be reduced to less than 1/3 of conventional rate to save the cost and stabilize shoot vigor when tree height is lowered by severe pruning.

Current Status of Tree Height Estimation from Airborne LiDAR Data

Seran Hwang,이임평 대한원격탐사학회 2011 大韓遠隔探査學會誌 Vol.27 No.3

Most nations around the world have expressed significant concern in the climate change due to a rapid increase in green-house gases and thus reach an international agreement to control total amount of these gases for the mitigation of global warming. As the most important absorber of carbon dioxide, one of major green-house gases, forest resources should be more tightly managed with a means to measure their total amount, forest biomass, efficiently and accurately. Forest biomass has close relations with forest areas and tree height. Airborne LiDAR data helps extract biophysical properties on forest resources such as tree height more efficiently by providing detailed spatial information about the wide-range ground surface. Many researchers have thus developed various methods to estimate tree height using LiDAR data, which retain different performance and characteristics depending on forest environment and data characteristics. In this study, we attempted to investigate such various techniques to estimate tree height, elaborate their advantages and limitations, and suggest future research directions. We first examined the characteristics of LiDAR data applied to forest studies and then analyzed methods on filtering, a precedent procedure for tree height estimation. Regarding the methods for tree height estimation, we classified them into two categories: individual tree-based and regression-based method and described the representative methods under each category with a summary of their analysis results. Finally, we reviewed techniques regarding data fusion between LiDAR and other remote sensing data for future work.

Current Status of Tree Height Estimation from Airborne LiDAR Data

Hwang, Se-Ran,Lee, Im-Pyeong The Korean Society of Remote Sensing 2011 大韓遠隔探査學會誌 Vol.27 No.3

Most nations around the world have expressed significant concern in the climate change due to a rapid increase in green-house gases and thus reach an international agreement to control total amount of these gases for the mitigation of global warming. As the most important absorber of carbon dioxide, one of major green-house gases, forest resources should be more tightly managed with a means to measure their total amount, forest biomass, efficiently and accurately. Forest biomass has close relations with forest areas and tree height. Airborne LiDAR data helps extract biophysical properties on forest resources such as tree height more efficiently by providing detailed spatial information about the wide-range ground surface. Many researchers have thus developed various methods to estimate tree height using LiDAR data, which retain different performance and characteristics depending on forest environment and data characteristics. In this study, we attempted to investigate such various techniques to estimate tree height, elaborate their advantages and limitations, and suggest future research directions. We first examined the characteristics of LiDAR data applied to forest studies and then analyzed methods on filtering, a precedent procedure for tree height estimation. Regarding the methods for tree height estimation, we classified them into two categories: individual tree-based and regression-based method and described the representative methods under each category with a summary of their analysis results. Finally, we reviewed techniques regarding data fusion between LiDAR and other remote sensing data for future work.

Review : Current Status of Tree Height Estimation from Airborne LiDAR Data

Se Ran Hwang,Im Pyeong Lee 大韓遠隔探査學會 2011 大韓遠隔探査學會誌 Vol.27 No.3

Most nations around the world have expressed significant concern in the climate change due to a rapid increase in green-house gases and thus reach an international agreement to control total amount of these gases for the mitigation of global warming. As the most important absorber of carbon dioxide, one of major green-house gases, forest resources should be more tightly managed with a means to measure their total amount, forest biomass, efficiently and accurately. Forest biomass has close relations with forest areas and tree height. Airborne LiDAR data helps extract biophysical properties on forest resources such as tree height more efficiently by providing detailed spatial information about the wide-range ground surface. Many researchers have thus developed various methods to estimate tree height using LiDAR data, which retain different performance and characteristics depending on forest environment and data characteristics. In this study, we attempted to investigate such various techniques to estimate tree height, elaborate their advantages and limitations, and suggest future research directions. We first examined the characteristics of LiDAR data applied to forest studies and then analyzed methods on filtering, a precedent procedure for tree height estimation. Regarding the methods for tree height estimation, we classified them into two categories: individual tree-based and regression-based method and described the representative methods under each category with a summary of their analysis results. Finally, we reviewed techniques regarding data fusion between LiDAR and other remote sensing data for future work.