National Geographic Information Institute

Abstract We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within of the ecliptic plane that are suitable as calibrators for anticipated phase referencing observations of spacecraft, and determine their positions with accuracy at the 1.5 nrad level. We run the program in two modes: search and refine. In the search mode, a complete sample of all sources brighter than 50 mJy at 5 GHz listed in the Parkes-MIT-NRAO and Green Bank 6 cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By 2016 October, thirteen 24 hr sessions that targeted all sources brighter than 100 mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.

In this manuscript, a new methodology based on a deep learning model using a Siamese network and attention module was proposed to classify crop cultivation areas, such as onion and garlic, from multitemporal PlanetScope images in South Korea. To consider the seasonal characteristics of crops in the model, training data were constructed from multitemporal satellite images. It was generated using PlanetScope satellite imagery from January and April, corresponding to the seasonal growth period of onion and garlic, in South Korea. Image patches were generated by considering the ratio of crops to minimize the influence of imbalanced data in the training process. Siamese FC-DenseNet with an attention module model (SFC-DenseNet-AM) is proposed, and the attention module is used to classify cultivated crop areas. Based on the proposed network, we extract cultivated crop areas using preliminary cultivation information. The results of the experiment using PlanetScope images indicate that image classification for cultivated areas was effectively performed using the proposed deep learning model. The model's performance, with F1-scores of 0.823 (garlic) and 0.774 (onion), was verified through an ablation study.

The East Asian VLBI Network (EAVN) is an international VLBI facility in East Asia and is operated under mutual collaboration between East Asian countries, as well as part of Southeast Asian and European countries. EAVN currently consists of 16 radio telescopes and three correlators located in China, Japan, and Korea, and is operated mainly at three frequency bands, 6.7, 22, and 43 GHz with the longest baseline length of 5078 km, resulting in the highest angular resolution of 0.28 milliarcseconds at 43 GHz. One of distinct capabilities of EAVN is multi-frequency simultaneous data reception at nine telescopes, which enable us to employ the frequency phase transfer technique to obtain better sensitivity at higher observing frequencies. EAVN started its open-use program in the second half of 2018, providing a total observing time of more than 1100 h in a year. EAVN fills geographical gap in global VLBI array, resulting in enabling us to conduct contiguous high-resolution VLBI observations. EAVN has produced various scientific accomplishments especially in observations toward active galactic nuclei, evolved stars, and star-forming regions. These activities motivate us to initiate launch of the ’Global VLBI Alliance’ to provide an opportunity of VLBI observation with the longest baselines on the earth.

Context. We highlight the capabilities of geodetic VLBI technique to test general relativity in the classical astrometric style, i.e. measuring the deflection of light in the vicinity of the Sun. Aims. In previous studies, the parameter γ was estimated by global analyses of thousands of geodetic VLBI sessions. Here we estimate γ from a single session where the Sun has approached two strong reference radio sources, 0229+131 and 0235+164, at an elongation angle of 1–3°. Methods. The AUA020 VLBI session of 1 May 2017 was designed to obtain more than 1000 group delays from the two radio sources. The solar corona effect was effectively calibrated with the dual-frequency observations even at small elongation. Results. We obtained γ with a greater precision (0.9 × 10−4) than has been obtained through global analyses of thousands of standard geodetic sessions over decades. Current results demonstrate that the modern VLBI technology is capable of establishing new limits on observational tests of general relativity.

Context . We highlight the capabilities of geodetic VLBI technique to test general relativity in the classical astrometric style, i.e. measuring the deflection of light in the vicinity of the Sun. Aims . In previous studies, the parameter γ was estimated by global analyses of thousands of geodetic VLBI sessions. Here we estimate γ from a single session where the Sun has approached two strong reference radio sources, 0229+131 and 0235+164, at an elongation angle of 1–3°. Methods . The AUA020 VLBI session of 1 May 2017 was designed to obtain more than 1000 group delays from the two radio sources. The solar corona effect was effectively calibrated with the dual-frequency observations even at small elongation. Results . We obtained γ with a greater precision (0.9 × 10 −4 ) than has been obtained through global analyses of thousands of standard geodetic sessions over decades. Current results demonstrate that the modern VLBI technology is capable of establishing new limits on observational tests of general relativity.

We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within 7○̣5 of the ecliptic plane that are suitable as calibrators for anticipated phase referencing observations of spacecraft, and determine their positions with accuracy at the 1.5 nrad level. We run the program in two modes: search and refine. In the search mode, a complete sample of all sources brighter than 50 mJy at 5 GHz listed in the Parkes-MIT-NRAO and Green Bank 6 cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By 2016 October, thirteen 24 hr sessions that targeted all sources brighter than 100 mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.

Unmanned aerial vehicles (UAVs) are becoming an economical and efficient means to create digital maps, but until now, the vectorization method has been used to extract topographic features from orthoimages for large-scale mapping. The aim of this study is to determine the potential of UAV photogrammetry for digital mapping with stereo plotting, which can include vertical position information. In this study, the entire work process of UAV photogrammetry was performed using a case study in Korea, where 314 images were acquired with a BirdsEyeView Aerobotics FireFly6 PRO. To compare the results, digital maps were created by stereo plotting and vectorization. To evaluate the accuracy of the digital maps created by stereo plotting, we evaluated the accuracy of the aerial triangulation (AT) work from ground control points (GCPs) and the position accuracy of the maps from checkpoints (CPs). The accuracy of the AT work was on the sub-centimeter order and the position accuracy of the maps was on the sub-decimeter order. We also compared a digital map produced by the Korean National Geographic Information Institute (NGII) with the maps created by stereo plotting and vectorization to evaluate the mapping accuracy. From the results of the comparison, we found that the maps created by stereo plotting were more accurate than those created by vectorization.

Currently, point cloud data acquired by using unmanned aerial vehicles (UAVs) are mostly used for the production of digital surface models (DSMs). This paper shows the possibility of digital elevation model (DEM) production with point cloud data acquired using UAVs. In this study, which was conducted in Korea, we used 314 images acquired with a DJI Inspire-2 UAV. To extract ground data, we performed point cloud auto-classification with six types of software, Pix4DMapper, GlobalMapper, Inpho, Trimble Business Center (TBC), Metashape, and Terrascan, and the obtained results were compared. Pix4DMapper was used for point cloud extraction, and all six types of software used the default options for point cloud autoclassification. A point cloud acquired using LiDAR classifies vegetation using an echo, but a point cloud extracted from an image has no echo, making it impossible to classify vegetation using an echo. In this study, DEMs were produced using ground data classified automatically with the six types of software, and they were compared with a DEM produced by the Korean National Geographic Information Institute (NGII). As a result, the DEM error rate was 38-47% depending on the type of software used. In a mountainous area, the dense forest made it impossible to extract ground data, resulting in a very high error rate of 82-92%.

The current status of buildings and roads is an essential element of land monitoring and management, and is used in various fields such as urban planning, disaster management, and change detection. With the recent advancement of deep learning technology, high-performance semantic segmentation techniques have become commonplace, and research on applying them to building and road detection has begun to be actively conducted. However, most of these studies are conducted overseas, so there are still limitations in applying them to Korean field. Therefore, in this study, we constructed a building and road detection dataset optimised for Korea using high-resolution Compact Advanced Satellite (CAS500) images and digital maps, and developed a detection model using the latest semantic segmentation models, the unified perceptual parsing network (UPerNet) based on the sifted window (Swin) transformer and the masked-attention mask transformer (Mask2Former), and compared and evaluated their performance. In particular, a systematic refinement process was used to minimise the spatiotemporal discrepancies between the satellite imagery and the digital maps, and a temporary dataset consisting of only pure digital map labels was created separately to evaluate the effectiveness of the dataset built in this way. The results of the building and road detection experiments showed that the Mask2Former model using the Swin-L backbone performed the best with a building intersection over union (IoU) of 77.93 and a road IoU of 74.85. In addition, the model trained with the optimised dataset in this study performed qualitatively and quantitatively better than the model trained with the pure digital map dataset, proving its effectiveness. The methodology and results of this study are expected to contribute to the efficiency of land status information construction and monitoring in Korea, and furthermore, it is expected that it can serve as a practical basis for the advancement of land spatial information services and the establishment of related policies.

Abstract. 3D geospatial information systems should provide efficient spatial analysis tools and able to use all capabilities of the third dimension, and a visualization. Currently, many human activities make steps toward the third dimension like land use, urban and landscape planning, cadastre, environmental monitoring, transportation monitoring, real estate market, military applications, etc. To reflect this trend, the Korean government has been started to construct the 3D geospatial data and service platform. Since the geospatial information was introduced in Korea, the construction of geospatial information (3D geospatial information, digital maps, aerial photographs, ortho photographs, etc.) has been led by the central government. The purpose of this study is to introduce the Korean government-lead 3D geospatial information web-based service for the people who interested in this industry and we would like to introduce not only the present conditions of constructed 3D geospatial data but methodologies and applications of 3D geospatial information. About 15% (about 3,278.74 km2) of the total urban area's 3D geospatial data have been constructed by the national geographic information institute (NGII) of Korea from 2005 to 2012. Especially in six metropolitan cities and Dokdo (island belongs to Korea) on level of detail (LOD) 4 which is photo-realistic textured 3D models including corresponding ortho photographs were constructed in 2012. In this paper, we represented web-based 3D map service system composition and infrastructure and comparison of V-world with Google Earth service will be presented. We also represented Open API based service cases and discussed about the protection of location privacy when we construct 3D indoor building models. In order to prevent an invasion of privacy, we processed image blurring, elimination and camouflage. The importance of public-private cooperation and advanced geospatial information policy is emphasized in Korea. Thus, the progress of spatial information industry of Korea is expected in the near future.

Abstract An intercontinental metrological clock comparison between Italy and the Republic of Korea was performed by means of geodetic K -band VLBI observations. The comparison involved the hydrogen masers (H-masers) used at Medicina and Sejong radio telescopes. The same clocks were simultaneously compared by a satellite link and by high-precision optical clocks maintained at the National Metrology Institutes, KRISS in Korea and INRIM in Italy, and delivered to VLBI antennas via optical fiber. The H-masers frequency difference was estimated by extrapolating the clock rate from VLBI data using two geodetic VLBI software. This was subsequently compared with clock differences derived by satellite link and by local optical clocks. Results obtained with different approaches were in agreement at the level of 10 −15 s s −1 . This pilot study demonstrates that standard high-frequency ( K -band) geodetic VLBI campaigns could be a viable approach to conduct intercontinental clock comparisons, now only possible via satellite links. This uncertainty can be reduced thanks to the planned installation of new-generation, broadband, high-frequency receivers on the involved telescopes. K / Q / W -band geodetic observations will allow an improvement of the accuracy of the resulting group delays through broad bandwidth synthesis from 20 to 100 GHz. Furthermore, the Frequency Phase Transfer method will also be explored together with the use of PCAL systems installed at the radio telescopes to improve phase stability and thus allow a better estimation of the station clock parameters.

Lee, J.-C.; Koh, Y.-C., and Lee, D.-H., 2021. Strategic improvement plan to increase the usability of coastal base maps throughout Korea. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 395–399. Coconut Creek (Florida), ISSN 0749–0208. The National Geographic Information Institute constructs and supplies coastal base maps containing spatial and geographic information. The main purpose is securing basic data for designing and developing coastal waters. However, there has been no continuous construction of information for all coastal waters in Korea; therefore, detailed and precise coastal water information for each coastal situation cannot be provided. This study introduces a continuous and unified coastal base map for all coastal waters in Korea. The introduced map can be employed to provide coastal water information with high utility, and widely used not only in coastal construction projects but also in various industries related to the spatial development of coastal waters.

The problem of load deformation of the earth is revisited. As an extension of former studies, which dealt with the earth’s surface deformation induced by loading, the deformation inside of the earth is investigated. First, the radial functions of displacement in the earth due to zonal harmonic load of degree n are acquired. With the acquired radial functions and the load Love numbers, the vertical and horizontal components of the inside deformation of the earth due to a circular cap load are calculated. The perturbation in the earth’s rotational inertia tensor associated with this deformation is assessed.

Abstract. The volunteered geospatial information (VGI) will be efficient and cost-effective method for generating and sharing large disasterrelated geospatial data. The national mapping organizations have played the role of major geospatial collector have been moving toward the considering public participation data collecting method. Due to VGI can conduct to encourage public participation and empower citizens, mapping agency could make a partnership with members of the VGI community to help to provide well-structured geospatial data. In order to effectively be understood and sharing the public semantics, datasets and action model of the public participation GeoPortal, the implemented VGI-GeoPortal designated as the basis of ISO 19154, ISO 19101 and OGC Reference Model. The proof of concepts of VGI-GeoPortal has been implemented urban flooding use-case in Republic of Korea to collect from the public, and analyze disaster-related geospatial data including high-disaster potential information such as the location of poor drainage sewer, small signs of occurring landslide, flooding vulnerability of urban structure, and etc.

Color vision deficiency (CVD) is a visual condition caused by abnormalities in the retina's cone cells, impacting the ability to distinguish certain colors.This condition affects approximately 8% of males and 0.5% of females globally, with significant implications for interpreting visual information.Maps, as vital tools for spatial exploration, rely heavily on color differentiation to convey information such as land use, elevation, and geographic features.However, CVD users often struggle to discern these distinctions, reducing the usability of maps and increasing the risk of misinterpretation.This study addresses this gap by developing a novel map color transformation system tailored to CVD users.Using Daltonization techniques within the CIE Luv color space, the study enhances color differentiation for individuals with different types and degrees of CVD.The CIE Luv space, known for its perceptual accuracy, allows for precise manipulation of color distances, enabling transformations that maximize distinguishability while preserving naturalness.The method begins by clustering map colors using K-means clustering and calculating cluster centroids.These centroids are then adjusted based on Confusion Points and Lines unique to each type of CVD (protanopia, deuteranopia, and tritanopia).By optimizing the angular separation () between clusters in polar coordinates, the system ensures improved color differentiation for CVD users.

Fog is formed when water vapor in the atmosphere condenses into miniscule floating water droplets, rendering a visibility of less than 1 km. Fog causes economic damage and poses a hazard to people owing to limited visibility. Fog forecasts depend on the judgment and experience of the forecaster, who bases the forecast on analysis results from meteorological models and satellite images. However, such forecasts are complicated by spatiotemporal changes and fine physical processes. To address this issue, a variety of fog studies have used the Global Navigation Satellite System (GNSS) tropospheric signal delay as an alternative. In this study, we monitored fog and cloudiness by analyzing precipitable water vapor (PWV) extracted from GNSS tropospheric delay. The analysis of the change in PWV during fog generation showed that it is difficult to detect fog from PWV using GNSS; more precise GNSS processing is required. However, it was found that cloudiness affects the change in PWV. In particular, the change in PWV is affected by high-level and middle-level clouds rather than low-level clouds. In other words, we conducted research to detect fog and cloudiness, but it was difficult to monitor them using PWV calculated from GNSS, although the use of GNSS to monitor the high-level and middle-level clouds generated good results. The results of this study will aid in quantitative cloudiness measurements, which at present are mostly performed through non-quantitative visual inspection. Furthermore, these results are expected to be helpful in the development of automatic observation devices for cloudiness measurements, satellite image processing, and weather forecasting.

The volunteered geospatial information (VGI) will be efficient and cost-effective method for generating and sharing large disasterrelated geospatial data. The national mapping organizations have played the role of major geospatial collector have been moving toward the considering public participation data collecting method. Due to VGI can conduct to encourage public participation and empower citizens, mapping agency could make a partnership with members of the VGI community to help to provide well-structured geospatial data. In order to effectively be understood and sharing the public semantics, datasets and action model of the public participation GeoPortal, the implemented VGI-GeoPortal designated as the basis of ISO 19154, ISO 19101 and OGC Reference Model. The proof of concepts of VGI-GeoPortal has been implemented urban flooding use-case in Republic of Korea to collect from the public, and analyze disaster-related geospatial data including high-disaster potential information such as the location of poor drainage sewer, small signs of occurring landslide, flooding vulnerability of urban structure, and etc.

Korean National Land Satellite 1 has been launched with a mission to map national geospatial information and to monitor land resource and disasters on March 22, 2021. The satellite has a precise optical payload of 5 multi-spectral bands (Pan, R, G, B, and NIR). It observes the ground of 12 kilometers width at a 0.5m GSD (Ground Sample Distance) mainly over the Korean Peninsula and global areas of interest during at least four years.The product of National Land Satellite is classified to 4 levels: Basic geometry image based on initial satellite position (Level 1); Precise Ortho-rectified image (Level 2);Reproduced 2D/3D information only with Level 2 (Level 3); and Reproduced 2D/3D information with Precise image(Level 2/3) and other spatial information (Level 4). As the first 0.5m-scale satellite, Level 1 and Level 2 products are open and accessible to the Korean public. In case of Level 2 product, the average location accuracy shows about 1~4m in Korea, depending on the number of available Ground Control Points (GCP) and Level 2 product will produce North Korea Digital Map at 1:5,000 scale. The level 3 and level 4 will be serviced to the public in stage from 2023. The Korea national land satellite can be used to monitor disaster damage, especially for monitoring climate change caused by increasing greenhouse gas emissions through increasing plastic waste. In addition, it is expected that it can be used to generate high value-added spatial information such as 3D spatial information through convergence between various spatial information and land satellite information. Acknowledgment: This work was supported by Ministry of Land, Infrastructure and Transport (MOLIT) of Korean government and Korea Environment Industry & Technology Institute (KEITI) through Plastic-Free Specialized Graduate School funded by Korea Ministry of Environment (MOE).Keywords : #National Land Satellite, #CAS500, #High resolution, #0.5m, #Diaster #plastic waste #climate change

최근 전 세계적으로 국가별, 기관별, 목적별로 다양하게 구축된 공간정보를 단일한 위치기반으로 하는 데이터로 통합함으로써 각 자료 간 연계성 및 활용성을 높이고 있다. 본 연구에서는 새로운 국가측지기준의 도입에 따른 위치기준의 변화와 공간정보 분야의 seamless 데이터 서비스 요구에 효율적으로 대응할 수 있도록 새로운 국가 단일원점 평면직각좌표에 대한 연구를 수행하였다. 이를 위해 한반도 전역을 투영영역으로 설정하고 투영영역 내 발생하는 투영왜곡을 분석함으로써 이를 균질화 및 최소화할 수 있는 투영파라미터를 정의하였으며, 이에 대한 표준화 및 국제기구 등록방안을 제시하였다. 연구의 결과, 국가 단일원점 평면직각좌표계를 위한 최적의 투영식은 Hooijberg 투영식으로 분석되었으며, TM 투영을 위한 5가지 투영파라미터는 위도(<TEX>${\Phi}$</TEX>) <TEX>$38^{\circ}N$</TEX>, 경도(<TEX>${\lambda}$</TEX>) <TEX>$128^{\circ}E$</TEX>, 축척계수(K) 0.99924로 각각 분석되었다. 또한, 투영원점(<TEX>${\Phi}$</TEX>, <TEX>${\lambda}$</TEX>)에 대한 가수값(false Northing & Easting)은 국가지점번호제도의 도입을 고려하여 북쪽방향 700,000m, 동쪽방향 400,000m로 각각 설정하는 것이 적합하였다. As a worldwide trend, the spatial information that is established by country, institution and purpose is integrated into the data with a single spatial reference to improve the data connectivity and usability. In this study, a new national single origin plane rectangular coordinate system was studied to efficiently respond to the changes in the spatial reference according to the introduction of a new national geodetic standard and to the demand of seamless data service in the spatial information sector. For this purpose, the Korean Peninsula was set as the projection region and the projection distortion in the projection region was analyzed. The projection parameters were defined to homogenize and minimize the projection distortion, and their standardization and registration on the international organizations were conducted. The study on the required optimal projection equation resulted in the Hooijberg projection equation and projection parameters (<TEX>${\Phi}$</TEX>, <TEX>${\lambda}$</TEX>, K, N, E) resulted in <TEX>$38^{\circ}N$</TEX> and <TEX>$128^{\circ}E$</TEX> projection origin, and a scale factor of 0.99924. The proper false northing and easting were 700,000m N and 400,000m E, respectively, considering the introduction of country station index system.