• 한국정밀공학회지
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• 제30권4호
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• pp.383-389
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• 2013

Demand for high-rising building has arisen. However, its maintenance is usually executed by labour. It could have a severe problem. We proposed a gondola robot to solve it. In this paper, we designed a height estimation sensor for this gondola. It is consist of pan-tilt unit, ARS sensor, and laser sensor. The pan-tilt unit keeps the laser sensor to indicate the gravity direction by referencing the ARS. The laser sensor's range is vertical distance from gondola to ground. However, if there is an obstacle under the gondola, the distance includes its height. To filter it out, we apply a Kalman filter for the height estimation. If the estimated height is changed extremely, the filter decides that there is an obstacle. Then, it remembers the height of obstacle. Other extreme changes of height estimations are reflected. The experimental results using the proposed sensor system show detail flow of the height estimation.

• 대한원격탐사학회지
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• 제28권3호
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• pp.307-318
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• 2012

To understand forest structures, the Geoscience Laser Altimeter System (GLAS) instrument have been employed to measure and monitor forest canopy with feasibility of acquiring three dimensional canopy structure information. This study tried to examine the potential of GLAS dataset in measuring forest canopy structures, particularly maximum canopy height estimation. To estimate maximum canopy height using feasible GLAS dataset, we simply used difference between signal start and ground peak derived from Gaussian decomposition method. After estimation procedure, maximum canopy height was derived from airborne Light Detection and Ranging (LiDAR) data and it was applied to evaluate the accuracy of that of GLAS estimation. In addition, several influences, such as topographical and biophysical factors, were analyzed and discussed to explain error sources of direct maximum canopy height estimation using GLAS data. In the result of estimation using direct method, a root mean square error (RMSE) was estimated at 8.15 m. The estimation tended to be overestimated when comparing to derivations of airborne LiDAR. According to the result of error occurrences analysis, we need to consider these error sources, particularly terrain slope within GLAS footprint, and to apply statistical regression approach based on various parameters from a Gaussian decomposition for accurate and reliable maximum canopy height estimation.

• 대한원격탐사학회지
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• 제27권3호
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• pp.389-401
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• 2011

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.

• Journal of Forest and Environmental Science
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• 제33권3호
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• pp.187-196
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• 2017

The use of unmanned aerial vehicles (UAV) for the estimation of tree height is gaining recognition. This study aims to assess the effectiveness of tree height estimation of Pinus densiflora Sieb. et Zucc. and Pinus koraiensis Sieb. et Zucc. using digital surface model (DSM) generated from UAV-acquired imageries. Images were taken with the $Trimble^{(R)}$ UX5 equipped with Sony ${\alpha}5100$. The generated DSM, together with the digital elevation model (DEM) generated from a digital map of the study areas, were used in the estimation of tree height. Field measurements were conducted in order to generate a regression model and carry out accuracy assessment. The obtained coefficients of determination (R2) and root mean square error (RMSE) for P. densiflora (R2=0.71; RMSE=1.00 m) and P. koraiensis (R2=0.64; RMSE=0.85 m) are comparable to the results of similar studies. The results of the paired two-tailed t-test show that the two tree height estimation methods are not significantly different (p-value=0.04 and 0.10, alpha level=0.01), which means that tree height estimation using UAV imagery could be used as an alternative to field measurement.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.264-270
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• 2016

In this paper, we proposed a method which can detect pedestrians from CCTV video and estimate the height of the detected objects. We separate the foreground using Gaussian mixture model and the pedestrian is detected using the conditions such as the width-height ratio and the size of the candidate objects. In order to obtain the optimal model for estimating the height of pedestrian, we get many training data from the pedestrian whose height is known. Using these training data, we designed optimal Wiener height estimator and used to estimate the height of pedestrians. The height of the pedestrian at various distance is estimated and the accuracy is evaluated. In the experimental results, proposed method shows that it can estimate the height of pedestrian for various positions effectively.

• 한국해안·해양공학회논문집
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• 제35권4호
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• pp.84-94
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• 2023

재현기간에 따른 설계주기 추정에는 일반적으로 파고-주기 관계곡선을 이용한다. 본 연구에서는 설계주기 추정을 위한 파고-주기 관계곡선의 매개변수를 선형, 로버스트 선형, 비선형 함수를 이용하여 추정하고 그 계수를 비교-평가하였다. 매개변수 추정에 사용한 자료는 해양수산부(2019) 설계파고 추정에 사용한 연 최대 파고-주기 자료이며, 태풍, 비태풍 조건으로 구분하여 매개변수 추정에 이용하였다. 추정 매개변수는 해역의 지점에 따라 뚜렷한 차이를 보였으며, 추정기법의 경우에는 태풍 조건의 자료의 경우 비선형과 선형 기법이 큰 차이를 보이고 있는 것으로 파악되었다. 또한 SPM 공식과 GODA 공식을 평균하여 추정하는 Suh et al.(2008, 2010) 제안 방법은 절편 매개변수는 과소추정, 경사 매개변수는 과대 추정하는 것으로 파악되었으며, 해역의 국지적인 특성 반영에는 한계가 있는 것으로 판단된다.

• 전자공학회논문지SC
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• 제45권3호
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• pp.20-31
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• 2008

본 논문에서는 단일 카메라를 이용하여 영상 내에 존재하는 객체의 3차원 공간 상에서의 위치 및 높이를 추출하기 위한 기법을 제안한다. 본 논문에서 제안하는 방법은 영상으로 사영된 3차원 장면(scene)에 대한 기준 좌표계를 마커(marker)를 이용해서 설정한 다음, 대상 물체의 2차원 영상을 기준 좌표계로 직접 역사영(back-projection) 시킴으로써 대상 물체에 대한 3차원 공간에서의 위치 및 높이를 계산한다. 그리고 부정확한 카메라 교정으로 인하여 발생하는 역사영 오차를 마커의 기하학 정보를 이용해서 보정한다. 제안된 방법은 기존의 방법에서 주로 이용되던 소실점(vanishing point) 및 소실선(vanishing line) 등을 이용하지 않으며, 3차원 공간 내에서의 객체의 높이 및 위치의 동시 추정이 가능한 장점이 있다. 또한 단일 카메라만을 이용하여 필요한 위치 및 높이 정보를 추출하기 때문에 다중 카메라를 이용한 기법에서 발생할 수 있는 3차원 좌표계 상에서의 대응점의 모호성, 다수의 카메라를 정확히 교정시켜야 하는 어려움 등의 문제가 발생하지 않는다. 실험 결과를 통하여 제안된 기법의 정확도 및 안정성을 확인하였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.716-724
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• 2008

In the case of subsea tunnels, hydro-mechanical coupled analysis is necessary for an exact design and construction. The consideration of the overstretched ground condition is also required because they are usually located at the great depth unlike the usual tunnels. Many researches have been performed on the estimation of relaxed rock mass height. However, there have been no researches on the estimation of relaxed rock mass height under overstretched ground conditions. In this study, therefore, hydro-mechanical coupled analyses were performed under the overstressed ground conditions and the relaxed rock mass heights were estimated based on the contour of the local safety factor around a tunnel.

• 한국재료학회지
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• 제12권8호
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• pp.682-687
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• 2002

The three-dimensional estimation on the depth and height of flaw by using the difference of radiographic contrast density was studied. First, the specimens having artificial flaws of various depths and heights were prepared and the radiographic testing was performed. The radiographic depth of flaw was investigated and estimated on the effect of the scattered radiation with the change of distance between flaw and film. The height of flaw was estimated from the radiographic test with the reference specimen. The radiographic contrast with flaw depth decreased with increasing the flaw depth. The scattered radiation increased with increasing flaw depth and varied with the location between flaw and film. However, in the case of flaw height, the contrast density increased with increasing flaw height. It is thought due to the change in volume generating the scattered radiation which reaches a film.

• 한국멀티미디어학회논문지
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• 제20권7호
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• pp.1014-1023
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• 2017

In this paper, we propose a method for estimating the human height by using downward depth images. We detect a point with the lowest depth value in an object as top of the head and estimate the height by calculating the depth difference with the floor. Since the depth of the floor varies depending on the angle of the camera, the correction formula is applied. In addition, the binarization threshold is variably applied so that height can be estimated even when several people are adjacent. Simulation results show that the proposed method has better performance than the conventional methods. The proposed method is expected to be widely used in body measurement, intelligent surveillance, and marketing.