Hong‐Gyoo Sohn

Early 1960's reconnaissance satellite images are compared to more recent image and map data in an interannual and seasonal study of West Central Greenland margin fluctuations. From 1962 to 1992, ice sheet margins to the north and south of Jakobshavn Glacier retreated despite a decline in average summer temperatures. The retreat may be reversing along the southern flank of the ice stream where regional mass balance estimates are positive. From 1950 to 1996, the terminus of Jakobshavn Glacier seas

This paper exploits an effective water extraction method using SAR imagery in preparation for flood mapping in unpredictable flood situations. The proposed method is based on the thresholding method using SAR amplitude, terrain information, and object-based classification techniques for noise removal. Since the water areas in SAR images have the lowest amplitude value, the thresholding method using SAR amplitude could effectively extract water bodies. However, the reflective properties of water

Abstract This paper describes three mathematical modelling methods for high‐resolution declassified CORONA KH‐4B images. Since CORONA images are collected with a panoramic camera, several types of geometric distortions are involved. Two methods use the modified collinearity equations, and the third involves the terrain‐dependent rational function model (RFM) which is considered to be a generic sensor model. Comparative analysis of the three mathematical modelling methods is undertaken. The resul

We demonstrate a new technique to automatically map the margin of ice sheets using ERS-1 SAR and SPOT imagery. The technique relies on a series of image processing techniques including edge enhancement, dynamic thresholding, region growing, edge detection, and edge following. The mapping technique is used to measure temporal displacement of the ice sheet margin north and south of the Jakobshavn Glacier in Greenland. During the 4 year interval between 1988 and 1992 we find ice sheet margin advanc

This paper proposes a practical calibration solution for estimating the boresight and lever-arm parameters of the sensors mounted on a Mobile Mapping System (MMS). On our MMS devised for conducting the calibration experiment, three network video cameras, one mobile laser scanner, and one Global Navigation Satellite System (GNSS)/Inertial Navigation System (INS) were mounted. The geometric relationships between three sensors were solved by the proposed calibration, considering the GNSS/INS as one

With the incorporation of an automated fare-collection system into the management of public transportation, not only can the quality of transportation services be improved but also that of the data collected from users when coupled with smart-card technology. The data collected from smart cards provide opportunities for researchers to analyze big data sets and draw meaningful information out of them. This study aims to identify the relationship between travel patterns derived from smart-card dat

The accurate and dense reconstruction of high-quality 3D spatial information is essential for digital twin-based smart cities. Unmanned aerial vehicle (UAV)-based photogrammetry allows the 3D modeling of urban environments in the shortest possible time. Accurate georeferencing is a prerequisite for utilizing geospatial information. The geolocation accuracy of real-time kinematic (RTK)/post-processing kinematic (PPK) UAV-based photogrammetry is significantly high; however, RTK/PPK UAVs are costly

Abstract This paper presents an image matching technique for IKONOS satellite imagery based on rational function models (RFMs). This algorithm adopts the object‐space approach and reduces the search space to within the confined line‐shaped area called the piecewise matching line (PML). Also, the detailed procedure of generating 3D surface information using the RFM coefficients (RFCs) is introduced to illustrate an end‐user's point of view. The final digital elevation model (DEM) generated using

The foundational step in constructing a digital twin involves transforming the physical world into an immersive 3D virtual environment. Unmanned aerial vehicle (UAV)-based photogrammetry, mobile mapping system (MMS), and terrestrial laser scanning (TLS) serve as powerful tools for 3D reconstruction of urban environments. Given the distinctive strengths and weaknesses of each sensor, a multi-source point cloud registration technique is imperative to achieve a detailed and precisely geolocated 3D

This paper proposes a technique to estimate the distance between an object and a rolling shutter camera using a single image. The implementation of this technique uses the principle of the rolling shutter effect (RSE), a distortion within the rolling-shutter-type camera. The proposed technique has a mathematical strength compared to other single photo-based distance estimation methods that do not consider the geometric arrangement. The relationship between the distance and RSE angle was derived

The landslide, which occurred at Umyeon mountain (Mt. Umyeon) in Seoul, Korea in 2011, was a prime example that raised awareness about the landslide in the highly urbanized area. Although many studies have been done on Umyeon landslide, there is a lack of research that detects the area where the landslide occurred and quantifies the elevation changes through remote sensing data. In this regard, this paper aims to detect and assess topographic changes quantitatively over Mt. Umyeon by using digit