Choung-Hwan Park

Optimal Detection Range of RFID Tag for RFID-based Positioning System Using the k-NN Algorithm

Positioning technology to track a moving object is an important and essential component of ubiquitous computing environments and applications. An RFID-based positioning system using the k-nearest neighbor (k-NN) algorithm can determine the position of a moving reader from observed reference data. In this study, the optimal detection range of an RFID-based positioning system was determined on the principle that tag spacing can be derived from the detection range. It was assumed that reference tags without signal strength information are regularly distributed in 1-, 2- and 3-dimensional spaces. The optimal detection range was determined, through analytical and numerical approaches, to be 125% of the tag-spacing distance in 1-dimensional space. Through numerical approaches, the range was 134% in 2-dimensional space, 143% in 3-dimensional space.

3-D building extraction using IKONOS multispectral images

I. INTRODUCTION 3-D building reconstruction in urban areas is one of the highlighted issues in photogrammetry and remote sensing. Generated 3-D building information can be used in various fields such as urban planning, disaster management, navigation system, and cyber city. In order to extract 3-D building information, various attempts have been performed using aerial images, satellite images, LIDAR data, DSM (Digital Surface Model), DEM (Digital Elevation Model), and GIS (Geospatial Information System) thematic maps. Aerial and satellite images are the primary data sets used in most researches. Conventional 3-D building reconstruction techniques are divided into image-based and model-based approaches. Image-based approach utilizes all possible extracted data from the images. Several attempts to extract and construct 3-D building models using the aerial imagery were investigated[6]. These trials were failed to match the extracted buildings simultaneously since only edge information is not enough for successful matching. Although approaches using color information in satellite imagery were also performed[5], extraction method was limited only to color information. In model-based approach, buildings in the image are extracted using the prior building models. There

3-D building reconstruction using IKONOS multispectral stereo images

This paper presents an effective strategy to extract the buildings and to reconstruct 3-D buildings using high-resolution multispectral stereo satellite images. Proposed scheme containes three major steps: building enhancement and segmentation using both Background Discriminant Transformation (BDT) and ISODATA algorithm, conjugate building identification using the object matching with Hausdorff distance and color indexing, and 3-D building reconstruction using photogrammetric techniques. IKONOS multispectral stereo images were used to evaluate the scheme. As a result, the BDT technique was verified as an effective tool for enhancing building areas since BDT suppressed the dominance of background to enhance the building as a non-background. In building recognition, color information itself was not enough to identify the conjugate building pairs since most buildings are composed of similar materials such as concrete. When both Hausdorff distance for edge information and color indexing for color information were combined, all segmented buildings in the stereo images were correctly identified. Finally, 3-D building models were successfully generated using the space intersection by the forward Rational Function Model (RFM).

The combination of copper bromide laser, a 10 600 nm ablative carbon dioxide laser and intralesional triamcinolone for the treatment of hypertrophic thyroidectomy scars

ability of total skin thickness score (modified Rodnan TSS) in systemic sclerosis. J Rheumatol 1995; 22: 1281–1285. 8 Apras S, Ertenli I, Ozbalkan Z et al. Effects of oral cyclophosphamide and prednisolone therapy on the endothelial functions and clinical findings in patients with early diffuse systemic sclerosis. Arthritis Rheum 2003; 48: 2256–2261. 9 Takehara K. Treatment of early diffuse cutaneous systemic sclerosis patients in Japan by low-dose corticosteroids for skin involvement. Clin Exp Rheumatol 2004; 22: S87–S89.

An efficient 3-d positioning method from satellite synthetic aperture radar images

This paper describes an efficient 3-D positioning method of SAR image only using ephemeris data and a single control point. The proposed method is applied to RADARSAT-1 SGF images of which ephemeris information is not accurate enough to directly use for the dynamic geometric modeling. The RMSE of the 3-D model by using a single CP (Control Point) is 43.86m, while that of traditional method using 10 CPs is 45.79m in comparison with reference 3-D model generated from 1:5,000 digital topographic maps of the study area. The test results show that even without the use of many CPs, it is possible to generate similar accuracy of 3D-model comparable to traditional method.

Application of Rational Function Model to Satellite Images with the Correlation Analysis

RFM (Rational Function Model) is universally applicable to any types of sensors. The RFCs (Rational Function Coefficients) can be solved with or without knowing the physical sensor models. If the physical sensor model is available, so called terrain-independent solution can be used. Otherwise, the terrain-dependent solution should be applied. Most researches carried out recently have concentrated on the terrain-independent method, assuming that the physical sensor modelling is available. Most of high resolution satellite imagery launched recently, however, do not provide pertinent satellite ephemeris information to perform physical sensor model. For this it is required to have a general sensor model being independent on sensor types. In this case, the fitting accuracy of RFM highly depends on the terrain relief, the number of GCPs (Ground Control Points), and their distribution. Moreover the terrain-dependent RFM can be deteriorated by the over-parameterization among the polynomial coefficients. This research focused on the development of techniques to improve RFM solution, a matching technique, and the DEM (Digital Elevation Model) generation through the correlation analysis using the terrain-dependent solution. As a result, for KOMPSAT stereo image pairs over-parameterization problem has been successfully adjusted by choosing the optimal RFCs with the intensive correlation analysis. Also, the object space image matching technique using optimal RFCs could reduce searching area to a line. This matching algorithm adopted piecewise epipolar line for each corresponding height interval. Results show that the accuracy of image matching is reliable. About 55,180 matching points were obtained from object space image matching technique, and a DEM generated from these points shows the comparable accuracy with that of the DEM generated from the rigorous sensor model. RMS errors in northerly and easterly directions are 18.107 m and 32.278m respectively, and RMS errors in height direction is 34.577 m.

Stereo matching strategy for 3-d urban modeling

This paper proposes an effective matching strategy to reconstruct 3-D urban models in densely built-up areas. Proposed scheme includes two main steps: feature-based image matching using building recognition technique and 3-D building reconstruction using the refined Rational Function Coefficients (RFCs). Especially, our approach is focused on improving the matching efficiency in complex urban scenes. For this purpose, we first performed automatic building recognition between stereo images, and then we endowed all points of building edges with identifiers using edge tracing method. Each identifier plays an important role in reducing search space for image matching within points of same building. A standard IKONOS stereo product was used to evaluate the proposed algorithms. It turned out that the proposed method could automatically determine the initial position and could dramatically reduce search space for point matching. Also, it was demonstrated that the updated RFCs could provide high-quality 3-D urban models.

Digital ortho-image production for web GIS applications

This paper presents a true ortho-image generation scheme in urban areas for web GIS application such as urban management system. Proposed scheme includes the solution of conventional problems in normal ortho-image generation. Especially, our approach is focused on the automation and consistency of ortho-image in complex urban areas. For this purpose, we generated additionally plotted DSM (Digital Surface Model), which includes roads, high-level roads, bridges, and tunnels, automatically detected occlusion pixels and restored occlusion areas using a self-developed algorithm, and performed mosaic process using road-based seamlines. Total 2,677 aerial color images were used to create the so called true ortho-image map for Seoul metropolitan city. It turned out that the proposed method could generate true ortho-image map for urban areas with high positional accuracy and good visual consistency. The generated ortho-image database is being successfully operated by Seoul Metropolitan Aerial Photography Management Systems on the web and urban management systems.

Surface reconstruction using terrain-dependent rational function model

This study reports on the surface reconstruction from high resolution satellite imagery with the terrain-dependent RFM (rational function model). The study area covers 17 km/spl times/14 km with two pairs of stereo images. The overlapped area is taken from SPOT panchromatic and KOMPSAT (Korea Multi-Purpose Satellite) stereo images. The ground resolution of each image is 10 m and 6.6 m, respectively. We improved the accuracy of RFM using correlation analysis for both images. We then successfully created surface DEM (digital elevation model) for the overlapped areas of both images.