ACROSS-TRACK IMAGING ACCURACY ANALYSIS AND RESEARCH OF HIGH
RESOLUTION SATELLITE IMAGERY IN METROPOLITAN AREA
Wang Weian*, Qiao Gang, Tong Xiaohua, Bao Feng, Liu Chun, Wang Jianmei, Ye Qin, Liu Shijie, Wang Wei, Ou Jianliang, Xie
Huan, Wu Hangbin
Dept, of Surveying and Geo-informatics, Tongji University, 1239, Siping Road, Shanghai, China, 200092 -
weian@tongji.edu.cn
Commission WGs, WG IV/9
KEY WORDS: Accuracy Improvement, Ground Control Points, Rational Function Model, Topographic Mapping, Quickbird
ABSTRACT:
High Resolution Satellite Imagery (HRSI) is now being used more and more in city development. The geometric correction of HRSI
is the basis of all the image process work for other application such as acquisition and updating of topographic data. This paper first
discusses the background and details of Rational Function Model (RFM) which describes the coordinates in image space and object
space, and then two different schemes in both object space and image space are introduced. With different parameters, four kinds of
accuracy improvement models in both spaces are put forward and discussed, respectively. Conclusion is drawn that with more well
distributed Ground Control Points (GCPs), high geo-positioning accuracy can be obtained up to about 0.6 meter in plane direction
and 0.7 meter in height direction for QuickBird across-track stereo imagery in Metropolitan Area.
1. INTRODUCTION
With the development of urbanization and increasing changes
of infrastructure in city area, the high efficiency acquisition and
updating of urban basic topographic data (UBTD) are now
becoming more and more important. Many research institutes
have been studying the capability of HRSI for development and
construction of urban area due to comparable resolution
compared with aerial imagery.
The launch of IKONOS initialled the new era of earth
observation and digital mapping from commercial HRSI (Li
1998). Due to the advantages such as high resolution, short
revisit time, and wide swath, HRSI is a valuable and cost
effective data acquisition tool for a variety of mapping and GIS
applications (Habib, Shin et al. 2007; Li, Zhou et al. 2007; Qiao
et al. 2007). Both the IKONOS and QuickBird can provide
along-track stereo imagery which is obtained at almost the same
time and with the same orbit, and many research applications
are based on along-track stereo imagery. However, along-track
stereo imagery is not economic for mapping and applications
compared with across-track stereo imagery. For example, the
cost of along-track QuickBird stereo images is about 2 to 3
times than that of across-track stereo images, making it
imperative that detailed research is given on positioning
accuracy with across-track stereo imagery (Tao et al.; Qiao et al.
2007).
The positioning models of HRSI mainly include rigorous sensor
model (RSM) and RFM. The RFM has been used more and
more in practice as an alternative to the RSM because of its
sensor independent and easy calculation. Much more research
work has been found in detail concerning the positioning model
and the accuracy of RFM. Li (1998) discussed the potential
accuracy of IKONOS imagery for national mapping products
with satellite pushbroom CCD linear arrays. Di et al. (2003)
presented the geometric processing of IKONOS along-track
stereo imagery with the test data elevation range from 170m to
230m along the southern shore of Lake Erie, and achieved an
RSME of 1.2 m, 0.9 m and 1.6 m in X, Y, Z directions. Zhou
and Li (2000) demonstrated the potential accuracy of ground
points using simulated IKONOS along-track stereo image data,
and found that the ground point accuracy is 3 m (X and Y) and
2 m (Z) with 24 GCPs, and 12 m (X and Y) and 12 m (Z)
without GCPs. Li et al. (2007) investigated the accuracy in 3D
geo-positioning achieved by integrating IKONOS and
QuickBird along-track stereo imagery with an elevation range
between -29.7 and 31.9 m in south Tampa Bay, Florida. Fraser
et al. (2006) examined RFM block adjustment to yield sub-pixel
geo-positioning accuracy using along-track QuickBird stereo
image pairs and three multi-image IKONOS blocks with
elevation range differences from 50 m to 1280m, and accuracy
was obtained in along-tack direction 0.7 to 1 m, across-track
0.4-0.6 m, and height 06-1.0 m. Habib et al. (2007) conducted
rigorous and several approximate sensor models to investigate
the accuracy of ground coordinates over the city of Daejeon,
South Korea, where terrain height variation is about 300 meters,
using along-track IKONOS stereo imagery, and an accuracy of
2-3 m were achieved.
However, existing work mainly focus on the test areas
including mountainous and urban regions, which have distinct
height difference, while little work has been conducted in
planar metropolis, where very low relief and complex features
are considered to be the main obstacles in imagery positioning
process. Research is carried out based on the above situations as
precondition in this paper.
2. RFM AND UPDATING SOLUTIONS WITH
ADDITIONAL GCPS
2.1 RFM
The RFM are described in detail in Tao and Hu (2001) and
Grodecki and Dial (2003). Here is a brief introduction.
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