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KOMPSAT-2 DIRECT SENSOR MODELING AND GEOMETRIC 
CALIBRATION/VALIDATION 
Doo Chun Seo 3, *, Ji Yeon Yang 3 , Dong Han Lee 3 , Jeong Heon Song 3 , Hyo Suk Lim 3 
KARI, Satellite Information Research Institute, 115 Gwahangno, Yuseong-Gu, Daejeon, South Korea - (dcivil, jyang, 
dhlee, newsong, hslim)@kari.re.kr 
Commission I, WG 1/1 
KEY WORDS: KOMPSAT-2, Direct Sensor Modelling, Geometrie Calibration/Validation 
ABSTRACT: 
The KOrea Multi-Purpose Satellite-2 (KOMPSAT-2) was launched in July 2006 and the main mission of the KOMPSAT-2 is a high 
resolution imaging for the cartography of Korea peninsula by utilizing Multi Spectral Camera (MSC) images. The camera 
resolutions are 1 m in panchromatic scene and 4 m in multi-spectral imaging.This paper provides the geometric accuracy assessment 
of the KOMPSAT-2 high resolution image without ground control points, briefly introduces the sensor model, Rational Function 
Model and geometric calibration and validation of KOMPSAT-2. Also investigated and evaluated the obtained 3-dimensional terrain 
information using the MSC pass image and scene images acquired from the KOMPSAT-2 satellite. 
1. INTRODUCTION 
The Korea’s first high resolution satellite, KOMPSAT-2, was 
successfully launched by the Rockot launch vehicle from 
Plesetsk Cosmodrome in Northern Russia on 28 July 2006. 
The KOMPSAT-2 system consists of space segment, ground 
segment, and launch service segment, and various external 
interfaces including additional ground stations to support image 
data reception or launch and early operations. The space 
segment is a satellite consists of the spacecraft bus and payload. 
The main payload of KOMPSAT-2 is MSC (Multi-Spectral 
Camera). The MSC is a high spatial resolution imaging sensor 
which collects visible image data of the earth's sunlit surface. 
The MSC is a pushbroom-scanned sensor which incorporates a 
single nadir looking telescope. The sensor is submerged and 
rigidly attached to the spacecraft and the optical boresight of 
the telescope is aligned with the spacecraft +Z direction (nadir). 
The MSC collects PAN and MS monoscopic images of the 
earth. Stereoscopic images are made by ground processing of 
the images from multiple orbits. The MSC pointing is 
accomplished by rolling the spacecraft, as needed, so that the 
line of sight of the MSC may pass over the desired location or 
swath. The spacecraft has a roll capability of ±56 degrees to 
support special imaging revisit cases. 
At the nominal mission altitude with the spacecraft nadir 
pointing, the MSC collects data with a GSD of 1 meter for PAN 
and 4 meters for MS data and with a swath width of 
approximately 15 km. The MSC is designed to operate with a 
duty cycle of up to 20 % per orbit. All MSC electronics will 
provide full redundancies without a single point failure. Image 
telemetry data can be compressed on-board. 
The Mission orbit of the KOMPSAT-2 is a sun-synchronous 
circular orbit with an altitude of 685.13 ±1 km. The Orbit 
inclination is 98.13 ± 0.05 degrees and the eccentricity from 0 
to 0.001. The satellite operates with a nominal local time of 
ascending nodes of 10:50 AM +10/-15 min. Figure 1 shows 
ascending passes (solid lines) of the KOMPSAT-2 for 28 day 
and a boundary of contact (circle) between the KOMSPAT-2 
and the KARI site based on the minimum elevation for contact 
of 5 degrees. The satellite passes Korean region during the day 
along ascending orbits and during the night along descending 
orbits. The KOMPSAT-2 satellite is designed for an operational 
service life of 3 years on the mission orbit. 
The horizontal geo-location accuracy of KOMPSAT-2, without 
GCPs (Ground Control Points) is 80 meters CE90 for 
monoscopic image of up to 26 degrees off-nadir angle, after 
processing including POD (Precise Orbit Determination), 
PAD(Precise Attitude Determination) and AOCS (Attitude and 
Orbit Control Subsystem) sensor calibration. In case of multiple 
stereo images, without GCPs, the vertical geometric accuracy is 
less than 22.4 meters LE 90 and the horizontal geometric 
accuracy is less than 25.4 meters. 
The KOMPSAT-2 system provides surveillance of large scale 
disasters and their countermeasures, acquisition of independent 
high resolution images for GIS, and composition of printed 
maps and digitized image maps on domestic and overseas 
territories to users. 
The major objective of this investigation is to check and verify 
the geometrical performance when KOMPSAT-2 images are 
employed and briefly introduce the sensor model of 
KOMPSAT-2. 
2. KOMPSAT-2 SENSOR MODEL 
There are two types of sensor model for KOMPSAT-2, direct 
sensor model and Rational Function Model (RFM). In general, 
a sensor model relates object coordinates to image coordinates. 
Corresponding author.