Chinese Journal of Electronics
Vol.23, No.3, July 2014
Automated Landmark Matching of FY-2 Visible
Imagery with Its Applications to the On-Orbit
Image Navigation Performance Analysis and
Improvements
∗
YANG Lei
1,2
, FENG Xiaohu
1,2
,LVKe
3
and SHANG Jian
1,2
(1.National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China)
(2.Key Laboratory of Radiometric Calibration and Validation for Environmental Satellite, Beijing 100081, China)
(3.Graduate University of Chinese Academy of Sciences, Beijing 100080, China)
Abstract — To analysis and improve China Fengyun-
2 (FY-2, spin-stabilized geosynchronous meteorological
satellite) on-orbit Image navigation (IN) performance, an
automated landmark matching algorithm (FY-2 automated
landmark matching, FALM) for the Visible and infrared
spin scan radiometer (VISSR) visible channel has been
developed a t China National satellite meteorological cen-
ter (NSMC). FALM is based on a correlation algorithm
used to match the observed landmark to the correspond-
ing landmark extracted from the template. FALM can
overcome the previous methods’ shortcomings, such as the
dependency on ten-year long satellite data and US Defense
Mapping Agency data. Each step of FALM, generation of
the landmark templates, binarization processing for ob-
served images, image matching between observed images
and landmark templates are described. Exclusion of false
matching is done by several strict quality measures includ-
ing cloud contamination detection, prior knowledge check,
neighborhood filter and Hypothesis test. 400 days of FY-2
data have been processed by FALM and the results have
showed that mainly five factors which can influence the
FY-2 on-orbit IN p erformance: orbit control, the integrity
of the known IN parameters, the satellite viewing zone ad-
justment, beta angle computation and the moment of sun-
shine pressure. Because of FALM’s high processing speed
and accuracy, it is ready to put into op eration for the FY-
2 IN improvement, as well as for operational monitoring
purposes, and will be further developed for FY-4.
Key words — Automated landmark matching, FY-2,
On-orbit image navigation performance analysis.
I. Introduction
Feng yun-2 geostationary meteorological satellite ‘FY-2’ is
the first generation of China weather satellites. The goal of the
FY-2 is to maintain continuous and reliable operational, me-
teorological and environmental space observation system to
protect life and property. FY-2 is the key member of World
meteorological organization (WMO) Earth observation sys-
tem (EOS). Its satellite operation is at 86.5
◦
E, 105
◦
Eand
123.5
◦
E. The images of the Visible and infrared spin scan ra-
diometer (VISSR) on board the FY-2 spin-stabilized geosyn-
chronous meteorological satellites provide 1.25km visible chan-
nel and 5.0km IR channel observations. An accurate Image
navigation (IN) (here we refer to the conversion of the image
line and sample numbers into the latitude and longitude) is
an essential preprocessing for various operational applications
for meteorology and oceanography of FY-2 VISSR data. The
theoretical framework for IN is mature after many years
work
[1,2]
. The IN can be summarized as follows. Firstly, IN
needs to compute the viewing vector of the instrument. Then
transforming the viewing vector from the instrument related
coordinate system to the earth centered rotating coordinate
system, establishing the IN equation according to the obser-
vation geometry. Finally, computing the point at which the
sensor line of sight intersects the earth surface by an iterative
way. The image navigation mainly depends on the satellite
position, velocity vector and attitude, the real-time alignment
matrix between the satellite and the sensor, characteristics of
the sensor, and the timing of the images. All those param-
eters can be predicted within the required accuracy, but the
exact values are not always available in real time. Thus the im-
age navigation errors are inevitable. But, how to monitor and
reduce the on-orbit image navigation errors are crucial impor-
tant for the satellite application. Techniques exist which can
monitor the meteorological satellite images on-orbit IN perfor-
mance automatically. This is frequently accomplished by using
∗
Manuscript Received Feb. 2013; Accepted Apr. 2013. This work is supported by the National Natural Science Foundations of China
(No.61172113, No.91338109 and No.40975017).