• Journal of Astronomy and Space Sciences
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• v.27 no.4
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• pp.377-382
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• 2010

In lunar explorer development program, computer simulator is necessary to provide virtual environments that vehicle confronts in lunar transfer, orbit, and landing missions, and to analyze dynamic behavior of the spacecraft under these environments. Objective of simulation differs depending on its application in spacecraft development cycle. Scope of use cases considered in this paper includes simulation of software based, processor and/or hardware in the loop, and support of ground-based flight test of developed vehicle. These use cases represent early phase in development cycle but reusability of modeling results in the next design phase is considered in defining requirements. A simulator architecture in which simulator platform is located in the middle and modules for modeling, analyzing, and three dimensional visualizing are connected to that platform is suggested. Baseline concepts and requirements for simulator development are described. Result of trade study for selecting simulation platform and approaches of defining other simulator components are summarized. Finally, characters of lunar elevation map data which is necessary for lunar terrain generation is described.

• Proceedings of the KSRS Conference
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• v.2
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• pp.631-634
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• 2006

Three main important sources for establishing GIS are the orthomap in scale 1:5 000 with Ground Sampling Distance of 0,5m; DEM/DTM data with height error of ${\pm}$1,0m and topographic map in scale 1: 10 000. The new era with Very High Resolution Satellite (VHRS) images as IKONOS, QuickBird, EROS, OrbView and other ones having Ground Sampling Distance (GSD) even lower than 1m has been in potential for producing orthomap in large scale 1:5 000, to update existing maps, to compile general-purpose or thematic maps and for GIS. The accuracy of orthomap generated from VHRS image affects strongly on GIS reliability. Nevertheless, orthomap accuracy taken from VHRS image is at first dependent on chosen sensor geometrical models. This paper presents, at fist, theoretical basic of the Rational Polynomial Coefficient (RPC) model installed in the commercial ImageStation Systems, realized for orthorectifying VHRS images. The RPC model of VHRS image is a replacement camera mode that represents the indirect relation between terrain and its image acquired on the flight orbit. At the end of this paper the practical accuracies of IKONOS and QuickBird image orthorectified by RPC model on Canadian PCI Geomatica System have been presented. They are important indication for practical application of producing digital orthomaps.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.6 no.1
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• pp.22-29
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• 2003

This research aims at investigation of accuracy potential of RTK(Real-Time Kinematic) GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On The Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only 2% was achieved. This indicates that the coastal mapping. As a result, it has been revealed that every possible noise in surveying could be corrected and the accuracy could be improved. The accuracy of GPS data acquired in real time was as good as that acquired by post processing. It is expected that it will be useful for the analysis of coastal geographic characteristics because DTM(Digital Terrain Model) can be also constructed for the harbor reclamation, the dredging, and the variation of soil movement in a river.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.6
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• pp.314-323
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• 2005

This paper proposes a real-time 3D visualization system for situational awareness of Air force operations. This 3D system of situational awareness supports a high-level commander of Air force during the war game operations. These situation aware supporting data such as the aircraft track data of radar, aircraft schedule database, map and satellite image data are integrated into one structured data and those are visualized as 3D structure. By using an Out-of-Core method, we can visualize a 3D huge data in real-time in mobile notebook environment. The experiment shows several examples of 3D visualization supporting situation awareness for Air force operation.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.6
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• pp.547-557
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• 2016

Due to threats caused by social disasters, operating surveillance devices are essential for social safety. CCTV, infrared cameras and other surveillance equipment are used to observe threats. This research proposes a method for searching for the optimum location of surveillance sensors. A GA (Genetic Algorithm) was used, since this algorithm is one of the most reasonable and efficient methods for solving complex non-linear problems. The sensor specifications, a DEM (Digital Elevation Model) and VITD (Vector Product Interim Terrain Data) maps were used for input data. We designed a chromosome using the sensor pixel location, and used elitism selection and uniform crossover for searching final solution. A fitness function was derived by the number of detected pixels on the borderline and the sum of the detection probability in the surveillance zone. The results of a 5-sensor and a 10-sensor were compared and analyzed.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.217-223
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• 2014

With precise sensor position, attitude element, and imaging resolution, a simulated geospatial image can be generated. In this study, a satellite image is simulated using SPOT ortho-image and global elevation data, and the geometric similarity between original and simulated images is analyzed. Using a SPOT panchromatic image and high-density elevation data from a 1/5K digital topographic map data an ortho-image with 10-meter resolution was produced. The simulated image was then generated by exterior orientation parameters and global elevation data (SRTM1, GDEM2). Experimental results showed that (1) the agreement of the image simulation between pixel location from the SRTM1/GDEM2 and high-resolution elevation data is above 99% within one pixel; (2) SRTM1 is closer than GDEM2 to high-resolution elevation data; (3) the location of error occurrence is caused by the elevation difference of topographical objects between high-density elevation data generated from the Digital Terrain Model (DTM) and Digital Surface Model (DSM)-based global elevation data. Error occurrences were typically found at river boundaries, in urban areas, and in forests. In conclusion, this study showed that global elevation data are of practical use in generating simulated images with 10-meter resolution.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2010.04a
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• pp.251-252
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• 2010

Lately, airborne digital camera and airborne laser scanner in field of airborne surveying is used to build geography information such as DEM generation and terrain analysis. In this study, 3D position accuracy is compared medium format CCD camera RCD105 with high resolution airborne digital camera DMC. For this, test area was decided for aerial photograph and ground control points was selected in 1/1,000 scale digital map. In Result, Root Mean Square Error(RMSE) was analyzed between RCD105 and DMC after aerial triangulation.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.2 s.29
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• pp.11-15
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• 2004

Based on Geo-Spatial Information System(GSIS), we tried to develop three dimensional road simulation system of coastal region considering landscape in Jeju island. The 1:5000 digital map, microstation CAD and Inroads road design programs were used to design coastal road. To estimate landscape effect of the three dimensional road visual simulation we implemented three types road simulations that are the trees planted, the flowers planted and the trees and flowers planted road, respectively. From the study, we found that the three dimensional virtual technique was very useful tool to design the road considering landscape effect in ocean view terrain and to estimate the reasonable road characteristics.

• Journal of Ocean Engineering and Technology
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• v.17 no.3 s.52
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• pp.13-20
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• 2003

This research aims at investigation of accuracy potential of RTK(Real-Time Kinematic) GPS in combination with Echo Sounder(E/S) for the coastal mapping. Apart from this purpose, the accuracy of ambiguity resolution with the OTF(On The Fly) method was tested with respect to the initialization time. The result shows that the accuracy is better than 1cm with 5-minute initialization in the distance of 10km baseline. The seaside topography was measured by the RTK GPS only, on the other hand the seafloor topography was surveyed in combination of RTK GPS and E/S. Comparing to the volume of seaside measured by RTK GPS and digital topographical map, the difference of only $2\%$ was achieved. This indicates that the coastal mapping. As a result, it has been revealed that every possible noise in surveying could be corrected and the accuracy could be improved. The accuracy of GPS data acquired in real time was as good as that acquired by post processing. It is expected that it will be useful for the analysis of coastal geographic characteristics because DTM(Digital Terrain Model) can be also constructed for the harbor reclamation, the dredging, and the variation of soil movement in a river.

• Journal of the Korean Institute of Educational Facilities
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• v.21 no.2
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• pp.25-32
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• 2014

Many Korean university campuses are located on hilly terrain where the hierarchy of the path system is unclear. Therefore, it is difficult to analyze the pedestrian network through space syntax, in which only horizontal direction changes are considered as depths of space. The purpose of this study is to compare pedestrian movement patterns and space syntax analysis in order to find their relevance to each other and the relationship between them. We conducted a survey regarding the most-visited buildings and pathways at S-University, which is located on a hilly area in Seoul. The survey results were compared with the Space Syntax integration map by regression analysis. For the segments where the relationship between pedestrian volume and integration was weak, field observations were conducted. As a result, topographical aspects, functional aspects, and location aspects were observed as the main influential factors. In addition, the research proposes that adding an extra axial line per vertical directional change can potentially compensate for the low relevance of stairs. This study suggests the possibility and the necessity of three-dimensional space syntax programs and emphasizes the importance of campus planning for the pedestrian environment.