• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.109-119
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• 2016

The height datum of Korea is currently separated into land and sea, which makes it difficult to acquire homogeneous and accurate height information throughout the whole nation. In this study, we therefore tried to suggest the more effective way to transform the height information were constructed separately according to each height datum on land and sea to those on the unique height datum using precise geoid models and tidal observations in Korea. For this, Anmyeon island was selected as a study area to develop the precise geoid models based on the height datums land (IMSL) and sea (LMSL), respectively. In order to develop two hybrid geoid models based on each height datum of land an sea, we firstly develop a precise gravimetric geoid model using the remove and restore (R-R) technique with all available gravity observations. The gravimetric geoid model were then fitted to the geometric geoidal heights, each of which is represented as height datum of land or sea respectively, obtained from GPS/Leveling results on 15 TBMs in the study area. Finally, we determined the differences between the two hybrid geoid models to apply the height transformation between IMSL and LMSL. The co-tidal chart model of TideBed system developed by Korea Hydrographic and Oceanographic Agency (KHOA) which was re-gridded to have the same grid size and coverage as the geoid model, in order that this can be used for the height datum transformation from LMSL to local AHHW and/or from LMSL to local DL. The accuracy of height datum transformation based on the strategy suggested in this study was approximately ${\pm}3cm$. It is expected that the results of this study can help minimize not only the confusions on the use of geo-spatial information due to the disagreement caused by different height datum, land and sea, in Korea, but also the economic and time losses in the execution of coastal development and disaster prevention projects in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.609-611
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• 2013

There's little to obstacles obstructing communication in the sky. There are nearly fixed obstacles obstructing communication on the ground. But communication disruption can be occur frequently and unexpectedly on the sea surface. Especially, it is difficult for a small station which can be greatly affected by waves and low antenna height to secure the LOS for radio communication. In this paper, LOS and minimum antenna height is calculated due to changing wave height and Tx/Rx antenna height on the sea surface.

• Journal of Digital Convergence
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• v.18 no.11
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• pp.427-432
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• 2020

In order to establish an effective forest management plan, it is necessary to investigate tree management information such as tree height and DBH(Diameter at breast height). However, research on convergence and application of data acquisition technology to improve the efficiency of existing forest survey methods is insufficient. Therefore, in this study, tree management information was constructed and analyzed using point cloud data acquired through a 3D scanner. Data on the study site was acquired using fixed and mobile 3D scanners, and the efficiency of the mobile 3D scanner was presented through comparison of working hours. In addition, tree management information for object management was constructed by classifying vegetation by object using point cloud data, and by constructing information on chest height diameter and height. As a result of the accuracy evaluation compared with the conventional measurement method, the difference in tree height was 0.02-0.09m and DBH was 0.01-0.04m. If information on the location of vegetation and crowns of each object is constructed through additional research in the future, the efficiency of the work related to forest management information construction can be greatly increased.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.33 no.5
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• pp.407-414
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• 2015

Interest points are generally located at the pixels where height changes occur. So, interest points can be the significant pixels for DSM generation, and these have the important role to generate accurate and reliable matching results. Manual operation is widely used to extract the interest points and to match stereo satellite images using these for generating height information, but it causes economic and time consuming problems. Thus, a tie point extraction method using Harris-affine technique and SIFT(Scale Invariant Feature Transform) descriptors was suggested to analyze height information of buildings in this study. Interest points on buildings were extracted by Harris-affine technique, and tie points were collected efficiently by SIFT descriptors, which is invariant for scale. Searching window for each interest points was used, and direction of tie points pairs were considered for more efficient tie point extraction method. Tie point pairs estimated by proposed method was used to analyze height information of buildings. The result had RMSE values less than 2m comparing to the height information estimated by manual method.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.9
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• pp.1035-1042
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• 2014

Object recognition is one of the key technologies of the monitoring system for the prevention of various intelligent crimes. The height is one of the physical information of a person, and it may be important information for identification of the person. In this paper, a method which can detect pedestrians from CCTV images and estimate the height of the detected objects, is proposed. In this method, GMM (Gaussian Mixture Model) method was used to separate the moving object from the background and the pedestrian was detected using the conditions such as the width-height ratio and the size of the candidate objects. The proposed method was applied to the CCTV video, and the height of the pedestrian at far-distance, middle- distance, near-distance was estimated for the same person, and the accuracy was evaluated. Experimental results showed that the proposed method can estimate the height of the pedestrian as the accuracy of 97% for the short-range, 98% for the medium-range, and more than 97% for the far-range. The image sizes for the same pedestrian are different as the position of him in the image, it is shown that the proposed algorithm can estimate the height of pedestrian for various position effectively.

• Journal of Institute of Convergence Technology
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• v.12 no.1
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• pp.1-5
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• 2022

This paper describes an algorithm for generating a terrain using a noise function and a height map as one of the procedural terrain generation methods. The polygon mesh data structure to represent the generated terrain concisely and render it is also described. The Perlin noise function is used as the noise technique for terrain mesh, and the height data of the terrain is generated by combining the four noise waves. In addition, the terrain height information can be also obtained from actual image data taken from the satellite. The algorithm presented in this paper generates the geometry part of the polygon topography from the height data obtained, and generated a material for texture mapping with two textures, that is, a diffuse texture and a normal texture. The validity of the terrain method proposed in this paper is verified through application examples, and its possibility can be confirmed through performance verification.

• Spatial Information Research
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• v.20 no.3
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• pp.27-38
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• 2012

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.

• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.35-41
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• 2016

GNSS/Geoid positioning technology allows orthometric height determination using both the geoidal height calculated from geoid model and the ellipsoidal height achieved by GNSS survey. In this study, Network-RTK surveying was performed through the Benchmarks in the study area to analyze the possibility of height positioning of the Network-RTK. And the orthometric heights were calculated by applying the Korean national geoid model KNGeoid13 according to the condition of with site calibration and without site calibration and the results were compared. Simplex algorithm was adopted for liner programming in this study and the heights of all Benchmarks were calculated in both case of applying site calibration and does not applying site calibration. The results were compared to Benchmark official height of the National Geographic Information Institute. The results showed that the average value of the height difference was 0.060m, and the standard deviation was 0.072m in Network-RTK without site calibration and the average value of the height difference was 0.040m, and the standard deviation was 0.047m in Network-RTK with the application of the site calibration. With linearization method to obtain the optimal solution for observations it showed that the height determination within 0.033m was available in GNSS Network-RTK positioning.

• Journal of Korean Society for Geospatial Information Science
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• v.25 no.2
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• pp.57-65
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• 2017

The purpose of this study is to analyze the feasibility of using Global Navigation Satellite System(GNSS)/Geoid technology in determining orthometric height in mountain. For the study, a test bed was set up in and around Mount Jiri and GNSS surveying were conducted. The orthometric height of 39 benchmarks was determined by applying the EGM2008, KNGeoid13, and KNGeoid14 geoid models and the accuracy was estimated by comparing with the offical Benchmarks orthometric height value issued by National Geographic Information Institute(NGII) and finally, the results were analyzed with the Aerial Photogrammetry Work Regulations. As a result of the study, it was found that the accuracy of the orthometric height determination by GNSS/Geoid technology was ${\pm}7.1cm$ when the KNGeoid14 geoid model was applied. And also, it can be confirmed that it is usable for the less than 1/1000 plotting scales as a vertical reference point for the aerial triangulation in Aerial Photogrammetry.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.367-370
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• 2001

This paper proposes a new deterioration diagnostic technique for power facilities by analyzing the pulse-height analysis of leakage current. Until now, various deterioration diagnostic techniques to prevent power system failures by deterioration of power facilities are suggested, and most of which measures leakage current amplitude only as a estimation parameter. In this experiment, it is known that the pulse heights of the leakage current are increased according to deterioration progress as well as there comes remarkable changes in pulse height distribution thereto. Therefore, the use of pulse height distribution in deterioration diagnostic technique makes more accurate diagnosis than the conventional method by using only leakage current value. From the application test, it is confirmed that the proposed technique has sufficient performance to diagnose deterioration of power facilities.