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ORTHO-RECTIFICATION OF HJ-1A/1B MULTI-SPECTRAL IMAGE BASED ON THE 
GCP IMAGE DATABASE 
   
Guoyuan Li *, Huabin Wang, Canhai Li 
Satellite Surveying and Mapping Application Center. Beijing, China 
ligy@sasmac.cn 
KEY WORDS: HJ Satellite, Ortho-rectification, GCP Image Database, SIFT, Collinearity Equation 
ABSTRACT: 
HJ satellite is the abbreviation of the Small Satellite Constellation of Environment and Disaster Monitoring and Forecasting in 
China, which plays a very important role in forecasting and monitoring the environment problems and natural disasters. The ortho- 
rectification of HJ images aided by GCP(Ground Control Point) image database is presented in this paper. The GCP image 
database is constructed from historical LandSat-TM images and the GCP chip consists of image and geographic attribute 
information. Then auto-searching and matching algorithm is introduced and mis-matching elimination method is presented. The 
imaging model based on collinearity equation and the polynomial description of the attitude and position of scanning line is 
utilized for ortho-rectification. Four scene images are experimented and compared, and the result demonstrated the feasibility and 
high efficiency of the whole work flow. 
1. INTRODUCTION 
With the increase of global environment problems and natural 
disasters, the significance of remote sensing technology and 
satellite images has been further recognized around the world. 
In order to forecast and monitor the environment problems and 
natural disasters, China has launched the Small Satellite 
Constellation of Environment and Disaster Monitoring and 
Forecasting in 2008, which is short for HJ satellite. HJ-1A/1B, 
which can provide wide-area and multi-spectral satellite image 
with the 30m resolution, has played a very important role in 
obtaining satellite images during emergency management and 
disaster monitoring[1]. 
It is clear that geo-rectification is an indispensable step for the 
application of satellite images, especially the ortho-rectification. 
Only based on the geographic information from image, other 
information can be obtained more efficient and decision can be 
made more scientific [2]. As the rapid response of disaster and 
environment problems, automatic and high-efficiency geo- 
rectification is very important for HJ-1A/1B image. There are 
few researches on HJ-1 A/1B satellite geo-rectification, but the 
fact is clear for HJ-1A/1B that the measurement accuracy of 
attitude and position is very low, the attitude in particular, 
Which can not satisfy the positioning requirement using the 
figorous sensor model as SPOTS-HRS without or a few GCP 
points[3]. 
GCP Image Database, which consists of geography and image 
attribute information, plays an important role in geometric 
processing of remote sensing image, because it can offer 
sufficient Ground Control Points and the possibility of auto- 
matching. 
In this paper, the GCP Image Database based on the historical 
DOM image of Land-Sat TM, which has the same resolution 
with HJ-1A/1B multi-spectral image, and then auto-matching 
CORSA ANNE Ne RE 
between GCP image chips and HJ-1A/1B image is 
implemented, calculating the attitude and position of satellite 
using rigorous collinearity model based on the matching results 
is experimented. 
2. ANALYSES ON THE DIFFICULTIES OF HJ-1A/1B 
ORTHO-RECTIFICATION 
Analyses on the difficulties of HJ-1 A/1B ortho-rectification 
There are some mathematic or physic model about geo- 
rectification or ortho-rectification, such as Polynomial model, 
RFM(Rational Function Mode),Rigorous Sensor Model based 
on the image vector and ephemeris parameters and so on[3,4,5]. 
For the HJ-1A/1B images, due to the wide imaging area which 
is about 360km, the same polynomial model presenting the 
relation between image point and object point for one scene 
image can not satisfy the rectification requirement. What's 
more, the frequency of ephemeris information recording is 
about 8 second one time, and the interval is about 1831 
scanning lines according to the Line-Scanning time of HJ- 
1A/1B CCD camera. The low frequency of attitude recording 
and imprecise of ephemeris parameters especially the attitude, 
result in the imprecise position using the rigorous sensor model 
based on ephemeris information or RFM which is the implicit 
expression of rigorous sensor model. 
Furthermore, the wide imaging area increases the difficulty of 
collecting GCP points, especially the GCP data source and 
GCP matching [6]. As a result, the conventional rectification 
method by manually GCP collection operation is not realistic 
for rapid response requirement of HJ-1A/1B. Consequently, 
constructing GCP database and improving the efficiency of 
GCP searching and matching are extraordinarily important. 
Guoyuan Li Corresponding author. Major in Photogrammetry and Remote Sensing. Research focus on Remote Sensing Image 
and LIDAR data processing. E-mail: ligy@sasmac.cn.