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KEYWORDS:
SYSTEMATIC CORRECTION MECHANISM OF GEOMETRIC DISTORTIONS
IN THE KITSAT-1 CCD EARTH IMAGES
Impyeong Leet, Taejung Kimt, Soon D. Choi#
Research Fellowt, Directort
Satellite Technology Research Center (SaTReC)
Korea Advanced Institute of Science and Technology(KAIST)
373-1, Kusung-dong, Yusung-Ku, Taejon, 305-701, Korea
e-mail: iplee 9 satrec.kaist.ac.kr, tjkim 9 satrec.kaist.ac.kr
Commission Ill, Working Group III /1
ABSTRACT
Remote Sensing, Correction, Modeling, Distortion, Satellite, Geometric, Precision
The CCD Earth Image Experiment (CEIE) is one of the main payload of the KITSAT-1, an experimental micro-satellite.
Since it was launched on Oct. 10, 1992, the CEIE has taken more than 500 images on the Earth surface world-wide so
far. An image from space is very different from a feature on the real Earth surface due to diverse radiometric and
geometric
distortions. Preprocessing to remove those distortions has to take place before the image data is processed
and analyzed further for various applications. The images from the KITSAT-1 are dramatically distorted due to very poor
pointing ability of the satellite. Moreover, the attitude determination and control system (ADCS) of the KITSAT-1 does
not give sufficiently accurate attitude information because it cannot have attitude sensors enough to do it due to the
strict limitation of weight and volume like many other micro-satellites. Since many systematic geometric correction
mechanisms developed previously use fully accurate attitude information, they could not be appropriate for images from
micro-satellites such as the KITSAT-1. A new mechanism described here estimates attitude and position information
reversibly using ground control points selected from satellite images and maps. Then, It establishes a geometric model
based on the estimated information. This paper describes the procedure to perform geometric correction of the KITSAT-
1 CCD earth images and shows the result from this mechanism.
[A]
(&m, Bm)
9, T]
01,02,03
(Xm, ym)
A
B
C1
C2
C3
C4
C
Lco
Lca
L
M
R
R23
Nomenclature
the nth element of a matrix A.
the coordinates of the mth map ground control
points
the longitude and latitude of satellite ground
position in C4 system
satellite attitude parameters, rotation angles for
three axis :
the coordinates of the mth image ground control
points
a point on the CCD sensor
a point on the center of the lens
the coordinate system defined on the CCD
sensor
the coordinate system defined on the satellite
the coordinate system defined on the orbit
the coordinate system defined on the Earth
a point on the surface of the Earth
the L vector expressed in C2 system
the L vector expressed in C4 system
a vector from the point A to the point B
a vector from the point B to the point C
the radius of the Earth
a rotation matrix between C2 system and C3
system
a rotation matrix between C3 system and C4
system
the focal length of the lens
satellite altitude
the next predicted parameters from the current
ones.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B3. Vienna 1996
Pn the current estimated parameters
p a vector including six geometric model
parameters (64, 62, 63, à, N, h)
1. Introduction
The KITSAT-1, an experimental microsatellite, was
launched successfully on Oct. 10, 1992 by Ariane v52. Its
total mass is about 48.6 Kg and its dimension is 35.2 x
35.6 x 67.0 cm“. Four payloads are on board it to carry
out scientific and engineering experiments. They are CCD
Earth Image Experiment (CEIE), Digital Signal Processing
Experiment (DSPE), Cosmic Ray Experiment (CRE), and
Digital Store and Forward Communication Experiment
(DSFCE). All the payloads have worked well without any
failure and shown interesting results so far.(Kim et.
al,1993)(Lee et. al., 1993)
The CEIE consists of two different camera systems and a
transputer based image processing system. The CCD
camera systems use two aerial CCD sensor and capture
meteorological scale monochrome images in a 568x576
pixel format. One of them has a wide view angle(96°) and
low resolution(4 kmx4 km per pixel). The other has a
narrow view angle(12°) and high resolution(400mx400m
per pixel).(Yoo, 1994)
Since the KITSAT-1 was launched, the CEIE has taken of
more than 500 images world-wide so far. However, some
of them include abnormalities due to hardware and also
many images have much cloud cover. Consequently,
about 150 images were used for developing this
geometric correction mechanism.
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