Hoyong Ahn

Radiometric characterization and validation for the KOMPSAT-3 sensor

A radiometric characterization of the Korea Multi-Purpose Satellite (KOMPSAT) Series multispectral imagery was performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG). This paper presents a vicarious radiometric calibration performed by KARI and PKNU RSG in 2012 and 2014. Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3 sensors at Zuunmod, Mongolia and Goheung, South Korea, were significant for multispectral bands. KOMPSAT-3 calibration coefficients for all bands estimated in 2012 continued to agree well with calibration coefficients estimated in 2014 (within 1.5%). As a result of this study, KARI will update and publish the KOMPSAT-3 multispectral radiometric calibration coefficients as official values. The average difference in TOA reflectance between KOMPSAT-3 and Landsat-8 images over the Libya 4, Libya and Railroad Valley Playa, USA, in the red–green–blue region was under 3%, whereas in the near-infrared band, the TOA reflectance of KOMPSAT-3 was lower than that of Landsat-8 due to the difference in the bandwidths of two sensors. The KOMPSAT-3 sensor includes a bandwidth near 940 nm that can be strongly absorbed by water vapour and therefore displayed low reflectance.

An ecosystem service value assessment of land-use change in South Korea using remote sensing data and geographic information system

In Korea, rapid industrialization and economic growth have led to serious problems including reduced open space, environmental degradation, traffic congestion, and urban sprawl. These problems have been exacerbated by the absence of effective conservation and governance, and have resulted in various social conflicts. This study analyzed ecosystem service value over the past 20 years using previously reported coefficients. In addition, using logistic regression, we projected the land-cover distribution in 2020 according to the Environmental Conservation Value Assessment Map and analyzed ecosystem service value based on land use changes. Between 1985 and 2005, built-up areas had increased threefold. In the same time period, forest, grassland, and wetland areas decreased. Because of these trends, ecosystem service value decreased from 7,300 million USD to 6,525 million USD. By analyzing land-cover distribution with 2020 land-cover maps, we determined that farmland, grassland, and bare land areas had declined by approximately 24.3%. The 2020 land-cover map with considering ECVAM showed a decrease of 89 million USD in ecosystem service value, while the map without considering ECVAM showed a decrease of 165 million USD. The results of this analysis indicate that environmentally sustainable systems and urban development must be applied to achieve sustainable development and environmental protection.

Radiometric cross-calibration of KOMPSAT-3 with Landsat-8

This paper presents a radiometric cross calibration of KOMPSAT-3 AEISS based on Landsat-8 OLI. Cross calibration between the two sensors using simultaneous image pairs, acquired during an underfly event over the Libya 4 pseudo invariant calibration site (PICS) site. The spectral profile of the target comes from the near-simultaneous EO-1 Hyperion data over these sites for apply Spectral Band Adjustment Factor (SBAF). The results indicate that the Top Of Atmosphere (TOA) reflectance measurements for KOMPSAT-3 agree with Landsat-8 to within 5% after the application of SBAF. To validate radiometric coefficient, comparison TOA reflectance executed in north Virginia, USA. The difference in TOA reflectance was calculated to within a maximum ±1.55%. There was a huge improvement when the standard deviation altered from 0.1 to 0.01, when applying the SBAF. The result of radiometric coefficient presented here appear to be a good standard for maintaining the optical quality of the KOMPSAT-3, for which prelaunch, onboard, and vicarious calibration data are lacking.

Vicarious calibration of KOMPSAT-3 AEISS

This paper presents a vicarious radiometric calibration of the Korea Multi-Purpose Satellite-3 (KOMPSAT-3) performed by the Korea Aerospace Research Institute (KARI) and the Pukyong National University Remote Sensing Group (PKNU RSG) in 2012 and 2014. Correlations between top-of-atmosphere (TOA) radiances and the spectral band responses of the KOMPSAT-3 sensors at the Zuunmod, Mongolia and Goheung, South Korea sites were significant for multispectral bands. KOMPSAT-3 calibration coefficients for all bands estimated in 2012 continued to agree well with calibration coefficients estimated in 2014 (within 1.5%). The average difference in TOA reflectance between KOMPSAT-3 and Landsat-8 image over the Libya 4, Libya site in the red-green-blue (RGB) region was under 3%, whereas in the NIR band, the TOA reflectance of KOMPSAT-3 was lower than the that of Landsat-8 due to the difference in the band passes of two sensors. The KOMPSAT-3 sensor includes a band pass near 940 nm that can be strongly absorbed by water vapor and therefore displayed low reflectance. To overcome this, we need to undertake a detailed analysis using rescale methods, such as the spectral bandwidth adjustment factor (SBAF).